I know this is off topic but I have gotton so much information here I hope
to get an answer. I have an in line emergency battery powered sump pump that
will run about 5-6 hrs on a full charge. I wish to connect a second battery
to double the pumping time but I am not sure of the proper wiring. Option
number 1, I can hook the positive termimals together and the negative
together just like jumpstarting a car. Or option number 2, I can hook the
positive pump lead to battery 1 positive, then battery1 negative to battery
2 positive, then pump negative lead to battery 2 negative. I don't know
which way is better or if
one way will give me 24 volts going to the pump which I sure don't want. Any
help will be greatly recieved. Thank you all. Larri
--
larry in Cinci
Brain fart, meant to say
Wire batteries in PARALLEL
John
On Thu, 6 May 2004 19:10:50 -0400, "larry in cinci"
<[email protected]> wrote:
>I know this is off topic but I have gotton so much information here I hope
>to get an answer. I have an in line emergency battery powered sump pump that
>will run about 5-6 hrs on a full charge. I wish to connect a second battery
>to double the pumping time but I am not sure of the proper wiring. Option
>number 1, I can hook the positive termimals together and the negative
>together just like jumpstarting a car. Or option number 2, I can hook the
>positive pump lead to battery 1 positive, then battery1 negative to battery
>2 positive, then pump negative lead to battery 2 negative. I don't know
>which way is better or if
>one way will give me 24 volts going to the pump which I sure don't want. Any
>help will be greatly recieved. Thank you all. Larri
Don't do it.... Storage batteries have an internal resistance factor that
will discharge another battery connected in parallel unless they are exactly
equal in every way. difficult to achieve even if they are new identical
batteries. They will discharge each other. There is an isolator that is used
in motor homes etc. that will solve this problem. It is 2 diodes that will
allow current to flow out of each battery to a load (Your pump) only. It
must have a current capacity large enough for the load intended. You will
also require another isolator to charge them, Same idea, It will allow
current to flow from the charger to the batteries only and not between them.
Both isolators connected properly will allow normal function of double the
battery capacity but prevent a cross connection between them. One battery
connection can be commonly connected. There may be a combination unit
available. Check with a RV. supply co.
--
Chipper Wood
useours, yours won't work
"larry in cinci" <[email protected]> wrote in message
news:[email protected]...
> I know this is off topic but I have gotton so much information here I hope
> to get an answer. I have an in line emergency battery powered sump pump
that
> will run about 5-6 hrs on a full charge. I wish to connect a second
battery
> to double the pumping time but I am not sure of the proper wiring. Option
> number 1, I can hook the positive termimals together and the negative
> together just like jumpstarting a car. Or option number 2, I can hook the
> positive pump lead to battery 1 positive, then battery1 negative to
battery
> 2 positive, then pump negative lead to battery 2 negative. I don't know
> which way is better or if
> one way will give me 24 volts going to the pump which I sure don't want.
Any
> help will be greatly recieved. Thank you all. Larri
> --
> larry in Cinci
>
>
"Wes Stewart" <n7ws@_arrl.net> wrote in message
news:[email protected]...
> On Thu, 6 May 2004 17:04:19 -0700, "Chipper Wood" <[email protected]>
> wrote:
<snip>
> I've seen this same misinformation given in rec.outdoors.rv-travel
> several times. It is totally incorrect!
>
<snip>
> Lets me offer this simple analogy for parallel batteries, because they
> are nothing more than storage reservoirs for electrical energy.
> Consider two buckets (A & B) of water sitting on the floor with a pipe
> connecting them at the bottom. If you fill Bucket A, the level in B
> will rise right along with it. Likewise, if you remove water from
> either, the level of the opposite will drop the same amount. (The
> height of both above the floor will be equal; the principle of the
> water level)
>
> Note that one bucket *does not* drain the other. Why on Earth should
> it? Where would the energy go?
>
<snip>
> Connect the batteries in parallel (+ to +, - to -) and don't worry
> about it.
>
It is not good practice to directly connect batteries in parallel, as an
earlier response stated batteries do have internal resistance and unless the
batteries are exactly matched the higher charged battery will discharge to
the level of the lower one. If you don't believe it do the Kirchoff
analysis. In emergency situations batteries are connected in parallel, such
as when jump starting a car, but as you will notice there is an ititial
spark and heavy current flow from the donor battery trying to charge the
dead one.
The analogy of the two water buckets doesn't hold water in this case because
you overlook the connection between the individual cells of the batteries.
One cell can becomes high resistance, quite common, in which case the
capacity of that battery becomes virtually zero; or if a cell partially
shorts, due to buckling of the plates or sediment shorting the plates, in
which case the battery terminal voltage drops.
In professional installations the solution would be two batteries controlled
by a differential relay so when the first battery drops to its rated
discharge voltage it would be dropped from circuit and the second connected.
In this application the diode isolators would probably be the best
alternative.
Bernard R
"Wes Stewart" <n7ws@_arrl.net> wrote in message
news:[email protected]...
> On Fri, 7 May 2004 11:27:44 -0500, "Bernard Randall"
> <[email protected]> wrote:
>
> |
> |"Wes Stewart" <n7ws@_arrl.net> wrote in message
> |news:[email protected]...
> |> On Thu, 6 May 2004 17:04:19 -0700, "Chipper Wood" <[email protected]>
> |<snip>
> |> Connect the batteries in parallel (+ to +, - to -) and don't worry
> |> about it.
> |>
> |
> |It is not good practice to directly connect batteries in parallel, as an
> |earlier response stated batteries do have internal resistance and unless
the
> |batteries are exactly matched the higher charged battery will discharge
to
> |the level of the lower one.
>
> So what? Be an optimist, the battery with the lower terminal voltage
> has been *charged* to a high voltage. The total AH capacity remains
> the same except for the slight I^2R loss.
>
Totally false.
<snip>
> |In emergency situations batteries are connected in parallel, such
> |as when jump starting a car, but as you will notice there is an ititial
> |spark and heavy current flow from the donor battery trying to charge the
> |dead one.
>
> So what? *You* do a Kirchoff analysis and tell us why this surprises
> you.
> |
The only reason I mentioned the spark is that non electrical readers aren't
necessarily aware of what is happening.
> |The analogy of the two water buckets doesn't hold water in this case
because
> |you overlook the connection between the individual cells of the
batteries.
>
> That's why they're called "batteries", they are a collection of cells.
> I didn't overlook anything of the sort. But if this baffles you,
> change "batteries" to "single cells" and connect them in parallel.
> The charge/discharge analogy continues to "hold water."
As an EE you sure have some funny ideas, it's a series parallel operation.
>
>
> |One cell can becomes high resistance, quite common, in which case the
> |capacity of that battery becomes virtually zero;
>
> So what? If it has high internal series resistance, it becomes less
> of a voltage source and more of a current (limited) source. So it may
> not contribute to the load current, but it certainly doesn't detract
> from it either. The *high internal resistance* sure the hell isn't
> discharging anything, as was the misguided concern of the post to
> which I originally responded.
>
The big 'so what' is that the OPs concern was having sufficient capacity to
extend the run time of his emergency sump pump from 5-6 hours to 10-12
hours; with a straight parallel connection the user has litttle idea what is
happening to his battery pack unless he routinely tests both batteries, but
battery faults, either due to high resistance cells, or short circuited
cells will drastically cut down the battery capacity. The best solution is
to have a single battery pack of the required ampere/hour capacity and to
routinely test it.
If you need a more detailed discussion of parallel batteries have a look at
this link,
http://www.amplepower.com/pwrnews/parallel/, it doesn't outright condem
parallel connection, but it does show that the problem is not as clear as
Wes would like us to believe and is very dependent on the type of batteries
used.
Bernard R
"Wes Stewart" <n7ws@_arrl.net> wrote in message
news:[email protected]...
> On Fri, 7 May 2004 17:39:33 -0500, "Bernard Randall"
> <[email protected]> wrote:
>
>
> [SNIP]
>
>
> |If you need a more detailed discussion of parallel batteries have a look
at
> |this link,
> | http://www.amplepower.com/pwrnews/parallel/, it doesn't outright condem
> |parallel connection, but it does show that the problem is not as clear as
> |Wes would like us to believe and is very dependent on the type of
batteries
> |used.
>
> Thank you so much for providing this link, although I was already very
> aware of Ample Power's web site. You clearly read things differently
> than I. To save the other readers from digesting this, and to put you
> on point let's use *your* reference for further discussion.
>
>
> Remember how you got your panties all bunched up about cell shorts?
The reference I made to cell shorts was that the terminal voltage would be
lower with a cell shorted, I said nothing of any fire damage. What is the
result of this? Lower voltage and smaller capacity at the best, at the
worst a cell where it isn't a dead short but inhibits the cell from properly
charging but the internal resistance is sufficiently high to inhibit the
required current flow.
>
> Ample Power (your reference, remember) says:
>
> "It is our opinion based on reference 1 and 2 that disastrous cell
> shorts are not a major failure mechanism, and the consequences are, in
> any case, no more than what happens during equalization. Since the
> early 1960s when we designed our first battery charger, we have
> witnessed no dangerous situation that resulted from a cell short."
>
> End Quote
>
> And
>
> Quote:
>
> "Up to this point, we have attempted to define the scope of the issue,
> and examine the failure mechanisms and their consequences to parallel
> configurations. We find *nothing alarming* (emphasis added) about such
> practice in either liquid or sealed battery systems, as long as the
> batteries are properly instrumented and prudently cared for. We do
> favor sealed batteries over liquid batteries for parallel systems
> because of the consistency of cell chemistry, and the fact that we
> can't tamper with it accidentally. We don't promote an unlimited
> number of batteries in parallel. One limit is indicated by the answer
> to the shorted cell question that was asked above. There are other
> features of parallel systems that *are attractive* (emphasis added)."
>
> End Quote
>
> Earlier you said:
>
> |It is not good practice to directly connect batteries in parallel, as an
> |earlier response stated batteries do have internal resistance and unless
the
> |batteries are exactly matched the higher charged battery will discharge
to
> |the level of the lower one.
>
> To which I replied:
>
> "So what? Be an optimist, the battery with the lower terminal voltage
> has been *charged* to a high voltage. The *total AH capacity remains
> the same except* (emphasis added) for the slight I^2R loss."
>
> You replied:
>
> |"Totally false."
>
> But *your* reference says:
>
> Quote:
>
> "First, a parallel system allows more convenient sizes which yields a
> greater range of systems. For instance, a 100 Ah battery can be placed
> in parallel with a 200 Ah unit to obtain a total of 300 Ah. Charging
> proceeds as expected, with each battery receiving its share of the
> charge current, and *each reaching a full charge at the same time*
> (emphasis added). On discharge, each battery supplies current
> according to its relative capacity, and both batteries maintain the
> *same percent depth of discharge* (emphasis added)."
>
> End Quote
>
> As I said before, I stand by my remarks.
>
> Connect the frigging batteries in parallel and stop fretting about it.
In the paragraph you quoted above I believe you will find that they are
refering to two batteries of different a/h capacity, not a situation where
either battery is in fault condition whether it be one cell is high
resistance or shorted. In either of those cases their a/h capacity is
totally unknown. Or are you claiming that you can predict the a/h capacity
of a damaged cell??
This thread is discussing the situation as it applies to a sump system which
appears from the supplied information to be unattended. You claim to be an
EE, all the experienced engineers I have worked with don't look at
situations through rose colored glasses as you appear to advocate. Anyone
with an engineering background will have to take into account what happens
in the fault condition of a critical piece of equipment. In this case the
battery is one of those items. As I said in my initial post, and now
expand, if it is a critical application I would use 2 batteries with
separate chargers and a differential relay to auto change the batteries when
the first reached its rated dischage voltage.
Bernard R
Wes,
Actually I have used this configuration.... (Storage Batteries in parallel)
Back when cars were still 6 volt. Living in a cold winter climate I decided
to use two dissimilar 6 v. batteries in series to start my truck on cold
winter mornings using some relays and solenoids, paralleling them when not
starting, charging them together. Worked fine the first day. The next
morning they were both almost completely drained. After checking and
rechecking my circuits this continued until I added a switch to disconnect
one battery from the charging system when idle and connecting it only while
the truck was running. Walla ! solved the problem and worked great except
when I forgot to flip the switch when parking overnight. I devoted some time
and effort to find out why this had occurred and passed what information I
gathered along. If you have real experience with this situation, I would be
interested in your results. In theory, both theory and practice work. In
practice theory doesn't always cooperate.
--
Chipper Wood
useours, yours won't work
"Wes Stewart" <n7ws@_arrl.net> wrote in message
news:[email protected]...
> To the collective relief of the group this will be my last comment on
> this OT subject.
>
> On Fri, 7 May 2004 21:49:58 -0500, "Bernard Randall"
> <[email protected]> wrote:
> One respondent (probably repeating something he had read) gave out
> totally erroneous information thus:
>
> >"Don't do it.... Storage batteries have an internal resistance factor
that
> >will discharge another battery connected in parallel unless they are
exactly
> >equal in every way. difficult to achieve even if they are new identical
> >batteries. They will discharge each other....."
>
> Because the correct answer was given before I read the OP, I did not
> reply until the foregoing was posted. I offered a simple analogy in
> layman's terms of why this statement was incorrect and explained the
> operation of battery isolators in the same gentle terms.
Chipper Wood responds:
>ctually I have used this configuration.... (Storage Batteries in parallel)
>Back when cars were still 6 volt. Living in a cold winter climate I decided
>to use two dissimilar 6 v. batteries in series to start my truck on cold
>winter mornings using some relays and solenoids, paralleling them when not
>starting, charging them together. Worked fine the first day. The next
>morning they were both almost completely drained. After checking and
>rechecking my circuits this continued until I added a switch to disconnect
>one battery from the charging system when idle and connecting it only while
>the truck was running. Walla ! solved the problem and worked great except
>when I forgot to flip the switch when parking overnight. I devoted some time
>and effort to find out why this had occurred and passed what information I
>gathered along. If you have real experience with this situation, I would be
>interested in your results. In theory, both theory and practice work. In
>practice theory doesn't always cooperate.
We used to keep a hotshot battery on hand (and on trickle charge) when it got
down below zero. I'd like to use one now on the idiot driving around the
neighborhood with his mobile junker booming out sound! Anyway, we'd hotshot the
start and disconnect, using the standard in-car 12 volt plus a second 12 volt
in series. The single battery wouldn't even turn the engine over (good old days
of 10 to 1 compression ratios, too, which added to oil as thick as cold road
tar, made for real fun) at minus 20 or so. Tap in the second battery and it was
"whirr, whirr, boomble, boomble, boomble ('68 Barracuda 340S). That was one
bitchin' winter.
I think that was the winter I discovered the efficacy of 2/0 welding cable as
the basis for starter cables, too.
Charlie Self
"Don't let yesterday use up too much of today." Will Rogers
Gothumbs does it again:
> I don't really think the original poster gives a crap about your
>past. He just wanted some information not what you once did.
Who are you writing to? And why? If you don't like the thread, pass it by. If
you think you're some kind of net cop, you're due for a big surprise.
Charlie Self
"Don't let yesterday use up too much of today." Will Rogers
On 08 May 2004 17:32:53 GMT, [email protected] (Charlie Self)
wrote:
|Chipper Wood responds:
|
|>ctually I have used this configuration.... (Storage Batteries in parallel)
|>Back when cars were still 6 volt. Living in a cold winter climate I decided
|>to use two dissimilar 6 v. batteries in series to start my truck on cold
|>winter mornings using some relays and solenoids, paralleling them when not
|>starting, charging them together. Worked fine the first day. The next
|>morning they were both almost completely drained. After checking and
|>rechecking my circuits this continued until I added a switch to disconnect
|>one battery from the charging system when idle and connecting it only while
|>the truck was running. Walla ! solved the problem and worked great except
|>when I forgot to flip the switch when parking overnight. I devoted some time
|>and effort to find out why this had occurred and passed what information I
|>gathered along. If you have real experience with this situation, I would be
|>interested in your results. In theory, both theory and practice work. In
|>practice theory doesn't always cooperate.
|
|We used to keep a hotshot battery on hand (and on trickle charge) when it got
|down below zero. I'd like to use one now on the idiot driving around the
|neighborhood with his mobile junker booming out sound! Anyway, we'd hotshot the
|start and disconnect, using the standard in-car 12 volt plus a second 12 volt
|in series. The single battery wouldn't even turn the engine over (good old days
|of 10 to 1 compression ratios, too, which added to oil as thick as cold road
|tar, made for real fun) at minus 20 or so. Tap in the second battery and it was
|"whirr, whirr, boomble, boomble, boomble ('68 Barracuda 340S). That was one
|bitchin' winter.
We don't have those winters in Tucson but I once did a lot of work on
my boss's '32 Ford three-window coupe. We installed a warmed-up '53
Olds engine and I totally rewired the car. The battery went into the
trunk and to overcome the voltage drop and the inefficient 6 V starter
I used an 8 V marine battery. The car had the brightest headlights in
town.
Damn, I wish I had that car now, or my old Cadillac-powered '36 Ford
convertible.
"J. Clarke" <[email protected]> wrote in message
news:[email protected]...
<snip>
>
> He's not looking for a solution for "a critical application", he's looking
> for a longer run time on a system that is working satisfactorily with a
> single battery. He's not dealing with a discharged or damaged battery,
> he's dealing with two batteries both of which will unless something
> malfunctions be fully charged and in equilibrium at the start of
operation.
> Thus none of your concerns apply and I don't really understand why you're
> on about this.
>
> > Bernard R
>
> --
> --John
> Reply to jclarke at ae tee tee global dot net
> (was jclarke at eye bee em dot net)
The only person who knows if he is dealing with a critical application is
the OP. The OP as in many of the posts on this and other NGs by the
nature of his question is asking a basic question which shows either
directly or indirectly that he does not know the full ramifications of his
actions. Hopefully, through discussion, he will take the appropriate action
depending on how critial he considers the application.
When dealing with batteries you are using an element which will ultimately
fail, fact of life, depending on how it is used will affect how soon it will
fail. However, battery powered equipment has many underlying potential
problems, only a few of which were even touched on it the original thread.
The bigest issue which was not discussed was what type of battery charger
was being used. From the OP it appeared that the battery was being
permanently float charged. Here I quote "A cheap, unregulated 'trickle'
charger or manual two stage charger can overcharge a battery and destroy
it". The full text of this can be seen at this link
http://www.uuhome.de/william.darden/carfaq16.htm
Maybe mistakenly I try and look beyond the basic question posed, and if I
see potential problems I try and bring them to the OPs notice, if he doesn't
consider my viewpoint applies he just ignores it, isn't that one of the
benefits of NGs?
Bernard R
In article <[email protected]>,
John <[email protected]> wrote:
>Wire batteries in SERIES
That's a shocking suggestion. and absolutely *WRONG* for the context.
wiring in series (pos to neg) gives double the voltage.
NOT what one wants for this kind of a situation.
>
>John
>
>On Thu, 6 May 2004 19:10:50 -0400, "larry in cinci"
><[email protected]> wrote:
>
>>I know this is off topic but I have gotton so much information here I hope
>>to get an answer. I have an in line emergency battery powered sump pump that
>>will run about 5-6 hrs on a full charge. I wish to connect a second battery
>>to double the pumping time but I am not sure of the proper wiring. Option
>>number 1, I can hook the positive termimals together and the negative
>>together just like jumpstarting a car. Or option number 2, I can hook the
>>positive pump lead to battery 1 positive, then battery1 negative to battery
>>2 positive, then pump negative lead to battery 2 negative. I don't know
>>which way is better or if
>>one way will give me 24 volts going to the pump which I sure don't want. Any
>>help will be greatly recieved. Thank you all. Larri
>
larry in cinci wrote:
> I know this is off topic but I have gotton so much information here I
> hope to get an answer. I have an in line emergency battery powered
> sump pump that will run about 5-6 hrs on a full charge. I wish to
> connect a second battery to double the pumping time but I am not sure
> of the proper wiring. Option number 1, I can hook the positive
> termimals together and the negative together just like jumpstarting a
> car. Or option number 2, I can hook the positive pump lead to battery
> 1 positive, then battery1 negative to battery 2 positive, then pump
> negative lead to battery 2 negative. I don't know which way is better
> or if
> one way will give me 24 volts going to the pump which I sure don't
> want. Any help will be greatly recieved. Thank you all. Larri
Use Option 1. Hook in parallel for extended power. Positive to negative
will double the voltage which you don't want (series).
Gary
larry in cinci wrote:
> I know this is off topic but I have gotton so much information here I hope
> to get an answer. I have an in line emergency battery powered sump pump that
> will run about 5-6 hrs on a full charge. I wish to connect a second battery
> to double the pumping time but I am not sure of the proper wiring. Option
> number 1, I can hook the positive termimals together and the negative
> together just like jumpstarting a car. Or option number 2, I can hook the
> positive pump lead to battery 1 positive, then battery1 negative to battery
> 2 positive, then pump negative lead to battery 2 negative. I don't know
> which way is better or if
> one way will give me 24 volts going to the pump which I sure don't want. Any
> help will be greatly recieved. Thank you all. Larri
> --
> larry in Cinci
You want to connect the positive to the positive and the negative to the
negative (in parallel). This will give the 12 volts with double the amp/hours.
Connecting the other way would be in series and WOULD result in 24 volts.
--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)
Chipper Wood wrote:
> Don't do it.... Storage batteries have an internal resistance factor that
> will discharge another battery connected in parallel unless they are exactly
> equal in every way. difficult to achieve even if they are new identical
> batteries. They will discharge each other.
Telco's run multiple cells connected in series to make up a "string" of the
required voltage. "Strings" are then paralleled to provide the required
amp/hour rating desired. The battery strings, rectifiers and load all connect
to a common buss. They do not use isolators. IIRC the cells we're now using
were installed in 1973.
A typical installation is pictured on page 5 of the following:
http://power.tycoelectronics.com/pdf/round-cell-batteries.pdf
--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)
Wes Stewart wrote:
> I've seen this same misinformation given in rec.outdoors.rv-travel
> several times. It is totally incorrect!
>
> Battery isolators are used in RVs for only one purpose; to isolate the
> "house" battery from the "starting" battery such that running down the
> house batteries doesn't leave you stranded. *That* is the function of
> the isolator.
<snip>
> Connect the batteries in parallel (+ to +, - to -) and don't worry
> about it.
I agree.
--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)
Bernard Randall wrote:
> It is not good practice to directly connect batteries in parallel, as an
> earlier response stated batteries do have internal resistance and unless the
> batteries are exactly matched the higher charged battery will discharge to
> the level of the lower one. If you don't believe it do the Kirchoff
> analysis. In emergency situations batteries are connected in parallel, such
> as when jump starting a car, but as you will notice there is an ititial
> spark and heavy current flow from the donor battery trying to charge the
> dead one.
<snip>
Do you think the spark may be caused by the fact that one of the batteries is
dead?
--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)
Telcos typically use -48 volt batteries. The diode drop for a combining
bridge is much less significant that when the battery stack is only 12
volts.
Even if Schotkey diodes are used the losses associated with the bridge
on a 12 volt system are significant.
RB
Nova wrote:
> Chipper Wood wrote:
>
>
>>Don't do it.... Storage batteries have an internal resistance factor that
>>will discharge another battery connected in parallel unless they are exactly
>>equal in every way. difficult to achieve even if they are new identical
>>batteries. They will discharge each other.
>
>
> Telco's run multiple cells connected in series to make up a "string" of the
> required voltage. "Strings" are then paralleled to provide the required
> amp/hour rating desired. The battery strings, rectifiers and load all connect
> to a common buss. They do not use isolators. IIRC the cells we're now using
> were installed in 1973.
>
> A typical installation is pictured on page 5 of the following:
>
> http://power.tycoelectronics.com/pdf/round-cell-batteries.pdf
>
> --
> Jack Novak
> Buffalo, NY - USA
> (Remove "SPAM" from email address to reply)
>
>
RB wrote:
> Telcos typically use -48 volt batteries. The diode drop for a combining
> bridge is much less significant that when the battery stack is only 12
> volts.
Telco's use individual 2 volt cells connected in series to give the required
voltage. 24V, 48V, and 130V "strings" are common. In my 35 years of telco work
I've never seen a 48 volt battery in any power plant I've worked on. They don't use
a combining bridge so the "diode drop" (whatever that is) does not apply.
--
Jack Novak
A power certified telco technician
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)
Thanks for such quick responses. I thought one way was wrong and the other
right but my begining electrical training is over 40 years ago and the mind
gets cloudy. Larry
"Nova" <[email protected]> wrote in message
news:[email protected]...
> larry in cinci wrote:
>
> > I know this is off topic but I have gotton so much information here I
hope
> > to get an answer. I have an in line emergency battery powered sump pump
that
> > will run about 5-6 hrs on a full charge. I wish to connect a second
battery
> > to double the pumping time but I am not sure of the proper wiring.
Option
> > number 1, I can hook the positive termimals together and the negative
> > together just like jumpstarting a car. Or option number 2, I can hook
the
> > positive pump lead to battery 1 positive, then battery1 negative to
battery
> > 2 positive, then pump negative lead to battery 2 negative. I don't know
> > which way is better or if
> > one way will give me 24 volts going to the pump which I sure don't want.
Any
> > help will be greatly recieved. Thank you all. Larri
> > --
> > larry in Cinci
>
> You want to connect the positive to the positive and the negative to the
> negative (in parallel). This will give the 12 volts with double the
amp/hours.
> Connecting the other way would be in series and WOULD result in 24 volts.
>
> --
> Jack Novak
> Buffalo, NY - USA
> (Remove "SPAM" from email address to reply)
>
>
Considering the disinformation being passed in this thread, I was going to
say something but, Wes, you have a good handle on it.
"Wes Stewart" <n7ws@_arrl.net> wrote in message
news:[email protected]...
> On Fri, 7 May 2004 11:27:44 -0500, "Bernard Randall"
> <[email protected]> wrote:
>
> |
> |"Wes Stewart" <n7ws@_arrl.net> wrote in message
> |news:[email protected]...
> |> On Thu, 6 May 2004 17:04:19 -0700, "Chipper Wood" <[email protected]>
> |> wrote:
> |<snip>
> |> I've seen this same misinformation given in rec.outdoors.rv-travel
> |> several times. It is totally incorrect!
> |>
> |<snip>
> |> Lets me offer this simple analogy for parallel batteries, because they
> |> are nothing more than storage reservoirs for electrical energy.
> |> Consider two buckets (A & B) of water sitting on the floor with a pipe
> |> connecting them at the bottom. If you fill Bucket A, the level in B
> |> will rise right along with it. Likewise, if you remove water from
> |> either, the level of the opposite will drop the same amount. (The
> |> height of both above the floor will be equal; the principle of the
> |> water level)
> |>
> |> Note that one bucket *does not* drain the other. Why on Earth should
> |> it? Where would the energy go?
> |>
> |
> |<snip>
> |> Connect the batteries in parallel (+ to +, - to -) and don't worry
> |> about it.
> |>
> |
> |It is not good practice to directly connect batteries in parallel, as an
> |earlier response stated batteries do have internal resistance and unless
the
> |batteries are exactly matched the higher charged battery will discharge
to
> |the level of the lower one.
>
> So what? Be an optimist, the battery with the lower terminal voltage
> has been *charged* to a high voltage. The total AH capacity remains
> the same except for the slight I^2R loss.
>
> |If you don't believe it do the Kirchoff
> |analysis.
>
> Oh please, I'm a retired EE, don't try to baffle me with big words.
>
> |In emergency situations batteries are connected in parallel, such
> |as when jump starting a car, but as you will notice there is an ititial
> |spark and heavy current flow from the donor battery trying to charge the
> |dead one.
>
> So what? *You* do a Kirchoff analysis and tell us why this surprises
> you.
> |
> |The analogy of the two water buckets doesn't hold water in this case
because
> |you overlook the connection between the individual cells of the
batteries.
>
> That's why they're called "batteries", they are a collection of cells.
> I didn't overlook anything of the sort. But if this baffles you,
> change "batteries" to "single cells" and connect them in parallel.
> The charge/discharge analogy continues to "hold water."
>
>
> |One cell can becomes high resistance, quite common, in which case the
> |capacity of that battery becomes virtually zero;
>
> So what? If it has high internal series resistance, it becomes less
> of a voltage source and more of a current (limited) source. So it may
> not contribute to the load current, but it certainly doesn't detract
> from it either. The *high internal resistance* sure the hell isn't
> discharging anything, as was the misguided concern of the post to
> which I originally responded.
>
>
> |or if a cell partially
> |shorts, due to buckling of the plates or sediment shorting the plates, in
> |which case the battery terminal voltage drops.
>
> So what? A failure can occur in a stand alone battery too. I guess
> that means we shouldn't use batteries; they might fail afterall.
>
> |
> |In professional installations the solution would be two batteries
controlled
> |by a differential relay so when the first battery drops to its rated
> |discharge voltage it would be dropped from circuit and the second
connected.
> |In this application the diode isolators would probably be the best
> |alternative.
>
> There are millions of RVs running around (one of them parked outside
> my house) and who knows how many solar energy installations that are
> using many multiples of parallel connected batteries. Do failures
> ever occur? Sure, usually from abuse in the charge/discharge cycle,
> but *not* because there is something inherently wrong with parallel
> connections. See:
>
> http://www.trojan-battery.com/technology_connection.htm
>
> I stand by my earlier remarks.
ROFLMAO at all the 'experts'...
...parallel batteries will not self discharge below the level of the lowest
voltage battery... period. Unless of course you are applying a load to
it/them and allow the discharge to continue until the battery capacity is
depleted. We ar talking relatively good batteries here.
Typical non-cellular CO TELCO batteries are float charged at
typically -54Vdc and 'equalize' charged at approximately -55.5Vdc -56Vdc.
All the small 1.2 - 1.3Vdc cells add up to the appropriate voltage. They
are monitored on a regular basis with an electrolyte check and are replaced
if the electrolyte or the cell voltage tests below a certain point (varies
per manufacturer). If you leave them without maintenance to
sulphate/short/self discharge, whatever you wanna call it , they will self
destruct and bring the overall voltage down to whatever the sum of the cell
voltages are, minus the lost cell until the internal resistance of the
defective battery causes more extensive problems in voltage level.
We are not talking TELCO batteries here...
Charging car batteries in parallel will work, with all things being
approximately equal, with the main concern being that the current capacity
of the charging equipment is adequate to charge the batteries at a trickle
rate. You are doubling the current capacity of the batteries and if the
battery charger design is good then no problem. It will take longer for the
batteries to fully charge though. If the dead batteries try to charge at a
rate higher than the charger is capable of providing on a steady basis, the
voltage will drop the batteries will not charge and the charger will likely
blow a fuse/pop a circuit breaker or whatever it does to protect itself when
excessive current is drawn for any length of time.
In a battery series circuit, a defective cell (battery) will cause problems
for the rest of the cells in the series. Unless you want the voltage to
increase, do not put them in series. If you want higher current capacity,
put them in parallel.
...just add me to the list of 'experts'
In news:[email protected],
larry in cinci <[email protected]> typed:
> I know this is off topic but I have gotton so much information here I
> hope to get an answer. I have an in line emergency battery powered
> sump pump that will run about 5-6 hrs on a full charge. I wish to
> connect a second battery to double the pumping time but I am not sure
> of the proper wiring. Option number 1, I can hook the positive
> termimals together and the negative together just like jumpstarting a
> car. Or option number 2, I can hook the positive pump lead to battery
> 1 positive, then battery1 negative to battery 2 positive, then pump
> negative lead to battery 2 negative. I don't know which way is better
> or if
> one way will give me 24 volts going to the pump which I sure don't
> want. Any help will be greatly recieved. Thank you all. Larri
In article <[email protected]>, "Bernard Randall" <[email protected]> wrote:
>It is not good practice to directly connect batteries in parallel, as an
>earlier response stated batteries do have internal resistance and unless the
>batteries are exactly matched the higher charged battery will discharge to
>the level of the lower one. If you don't believe it do the Kirchoff
>analysis. In emergency situations batteries are connected in parallel, such
>as when jump starting a car, but as you will notice there is an ititial
>spark and heavy current flow from the donor battery trying to charge the
>dead one.
Correct, and in fact if the recipient battery is "dead enough", the stranded
car won't start until that battery has built up some minimum level of charge.
For this reason, it's of the utmost importance to start the donor car first,
so that the energy needed to recharge the dead battery comes from the donor
car's *alternator* instead of its battery -- lest you wind up with *two* cars
needing a jump start.
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter,
send email to autoresponder at filterinfo-at-milmac-dot-com
You must use your REAL email address to get a response.
Wire them together using Option one, but instead of hooking the pump
directly to one battery, put the positive from the pump on one battery and
the negative from the pump on the other battery. That way, the bank will
appear to the charger and pump as one huge battery and you will eliminate
the problem of discharging one battery instead of both.
"larry in cinci" <[email protected]> wrote in message
news:[email protected]...
> I know this is off topic but I have gotton so much information here I hope
> to get an answer. I have an in line emergency battery powered sump pump
that
> will run about 5-6 hrs on a full charge. I wish to connect a second
battery
> to double the pumping time but I am not sure of the proper wiring. Option
> number 1, I can hook the positive termimals together and the negative
> together just like jumpstarting a car. Or option number 2, I can hook the
> positive pump lead to battery 1 positive, then battery1 negative to
battery
> 2 positive, then pump negative lead to battery 2 negative. I don't know
> which way is better or if
> one way will give me 24 volts going to the pump which I sure don't want.
Any
> help will be greatly recieved. Thank you all. Larri
> --
> larry in Cinci
>
>
Bernard Randall wrote:
>
> "Wes Stewart" <n7ws@_arrl.net> wrote in message
> news:[email protected]...
>> On Fri, 7 May 2004 17:39:33 -0500, "Bernard Randall"
>> <[email protected]> wrote:
>>
>>
>> [SNIP]
>>
>>
>> |If you need a more detailed discussion of parallel batteries have a look
> at
>> |this link,
>> | http://www.amplepower.com/pwrnews/parallel/, it doesn't outright condem
>> |parallel connection, but it does show that the problem is not as clear
>> |as Wes would like us to believe and is very dependent on the type of
> batteries
>> |used.
>>
>> Thank you so much for providing this link, although I was already very
>> aware of Ample Power's web site. You clearly read things differently
>> than I. To save the other readers from digesting this, and to put you
>> on point let's use *your* reference for further discussion.
>>
>>
>> Remember how you got your panties all bunched up about cell shorts?
>
> The reference I made to cell shorts was that the terminal voltage would be
> lower with a cell shorted, I said nothing of any fire damage. What is the
> result of this? Lower voltage and smaller capacity at the best, at the
> worst a cell where it isn't a dead short but inhibits the cell from
> properly charging but the internal resistance is sufficiently high to
> inhibit the required current flow.
> >
>> Ample Power (your reference, remember) says:
>>
>> "It is our opinion based on reference 1 and 2 that disastrous cell
>> shorts are not a major failure mechanism, and the consequences are, in
>> any case, no more than what happens during equalization. Since the
>> early 1960s when we designed our first battery charger, we have
>> witnessed no dangerous situation that resulted from a cell short."
>>
>> End Quote
>>
>> And
>>
>> Quote:
>>
>> "Up to this point, we have attempted to define the scope of the issue,
>> and examine the failure mechanisms and their consequences to parallel
>> configurations. We find *nothing alarming* (emphasis added) about such
>> practice in either liquid or sealed battery systems, as long as the
>> batteries are properly instrumented and prudently cared for. We do
>> favor sealed batteries over liquid batteries for parallel systems
>> because of the consistency of cell chemistry, and the fact that we
>> can't tamper with it accidentally. We don't promote an unlimited
>> number of batteries in parallel. One limit is indicated by the answer
>> to the shorted cell question that was asked above. There are other
>> features of parallel systems that *are attractive* (emphasis added)."
>>
>> End Quote
>>
>> Earlier you said:
>>
>> |It is not good practice to directly connect batteries in parallel, as an
>> |earlier response stated batteries do have internal resistance and unless
> the
>> |batteries are exactly matched the higher charged battery will discharge
> to
>> |the level of the lower one.
>>
>> To which I replied:
>>
>> "So what? Be an optimist, the battery with the lower terminal voltage
>> has been *charged* to a high voltage. The *total AH capacity remains
>> the same except* (emphasis added) for the slight I^2R loss."
>>
>> You replied:
>>
>> |"Totally false."
>>
>> But *your* reference says:
>>
>> Quote:
>>
>> "First, a parallel system allows more convenient sizes which yields a
>> greater range of systems. For instance, a 100 Ah battery can be placed
>> in parallel with a 200 Ah unit to obtain a total of 300 Ah. Charging
>> proceeds as expected, with each battery receiving its share of the
>> charge current, and *each reaching a full charge at the same time*
>> (emphasis added). On discharge, each battery supplies current
>> according to its relative capacity, and both batteries maintain the
>> *same percent depth of discharge* (emphasis added)."
>>
>> End Quote
>>
>> As I said before, I stand by my remarks.
>>
>> Connect the frigging batteries in parallel and stop fretting about it.
>
> In the paragraph you quoted above I believe you will find that they are
> refering to two batteries of different a/h capacity, not a situation where
> either battery is in fault condition whether it be one cell is high
> resistance or shorted. In either of those cases their a/h capacity is
> totally unknown. Or are you claiming that you can predict the a/h
> capacity of a damaged cell??
>
> This thread is discussing the situation as it applies to a sump system
> which
> appears from the supplied information to be unattended. You claim to be
> an EE, all the experienced engineers I have worked with don't look at
> situations through rose colored glasses as you appear to advocate. Anyone
> with an engineering background will have to take into account what happens
> in the fault condition of a critical piece of equipment. In this case the
> battery is one of those items. As I said in my initial post, and now
> expand, if it is a critical application I would use 2 batteries with
> separate chargers and a differential relay to auto change the batteries
> when the first reached its rated dischage voltage.
He's not looking for a solution for "a critical application", he's looking
for a longer run time on a system that is working satisfactorily with a
single battery. He's not dealing with a discharged or damaged battery,
he's dealing with two batteries both of which will unless something
malfunctions be fully charged and in equilibrium at the start of operation.
Thus none of your concerns apply and I don't really understand why you're
on about this.
> Bernard R
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Max wrote:
>> > Don't do it.... Storage batteries have an internal resistance factor
>> > that will discharge another battery connected in parallel unless they
>> > are exactly equal in every way. difficult to achieve even if they are
>> > new identical batteries. They will discharge each other.
>>
>> Telco's run multiple cells connected in series to make up a "string" of
>> the
>> required voltage. "Strings" are then paralleled to provide the required
>> amp/hour rating desired. The battery strings, rectifiers and load all
>> connect
>> to a common buss. They do not use isolators. IIRC the cells we're now
>> using were installed in 1973.
>>
>> A typical installation is pictured on page 5 of the following:
>>
>> http://power.tycoelectronics.com/pdf/round-cell-batteries.pdf
>
>
> A roomful of telco batteries that last for decades, "only need water every
> 10-15 years" and cost kilobucks is a very different beast than two car
> batteries in a basement.
>
> Larry -- this issue is known, understood, and -solved-. Use an isolator.
What do you believe "this issue" to be? Geez. Put the batteries in
parallel. Put them on a charger. They'll charge to the same voltage.
Eventually they'll self-discharge but that won't happen any faster than it
would if they were sitting on a shelf by themselves and with a
trickle-charger on them it's irrelevant anyway.
And I doubt that the telco pays "kilobucks" for a 2-volt cell.
> Max
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
To the collective relief of the group this will be my last comment on
this OT subject.
On Fri, 7 May 2004 21:49:58 -0500, "Bernard Randall"
<[email protected]> wrote:
|
|"Wes Stewart" <n7ws@_arrl.net> wrote in message
|news:[email protected]...
|> On Fri, 7 May 2004 17:39:33 -0500, "Bernard Randall"
|> <[email protected]> wrote:
[snip]
|This thread is discussing the situation as it applies to a sump system which
|appears from the supplied information to be unattended. You claim to be an
|EE, all the experienced engineers I have worked with don't look at
|situations through rose colored glasses as you appear to advocate. Anyone
|with an engineering background will have to take into account what happens
|in the fault condition of a critical piece of equipment. In this case the
|battery is one of those items. As I said in my initial post, and now
|expand, if it is a critical application I would use 2 batteries with
|separate chargers and a differential relay to auto change the batteries when
|the first reached its rated dischage voltage.
No, this thread began with:
|"I know this is off topic but I have gotton so much information here I hope
|to get an answer. I have an in line emergency battery powered sump pump that
|will run about 5-6 hrs on a full charge. I wish to connect a second battery
|to double the pumping time but I am not sure of the proper wiring."
The OP simply wanted to know whether to connect a second battery in
series or parallel. Many respondents before I gave him the correct
answer.
Note that the OP simply wanted to increase the Ah capacity of his
battery. He did not ask about redundancy, automatic changeover, or
anything about unattended operation. Perhaps he should have, but he
didn't seem to be concerned about it, so neither am I.
One respondent (probably repeating something he had read) gave out
totally erroneous information thus:
>"Don't do it.... Storage batteries have an internal resistance factor that
>will discharge another battery connected in parallel unless they are exactly
>equal in every way. difficult to achieve even if they are new identical
>batteries. They will discharge each other....."
Because the correct answer was given before I read the OP, I did not
reply until the foregoing was posted. I offered a simple analogy in
layman's terms of why this statement was incorrect and explained the
operation of battery isolators in the same gentle terms.
Apparently itching to complicate things, you started off with:
|"It is not good practice to directly connect batteries in parallel...."
and then offered as a reference a document that says:
"Up to this point, we have attempted to define the scope of the issue,
and examine the failure mechanisms and their consequences to parallel
configurations. We find nothing alarming about such practice in either
liquid or sealed battery systems....."
Your reference and I seem to agree.
I'm gonna go cut some wood now.
On Sat, 8 May 2004 09:08:02 -0700, "Chipper Wood" <[email protected]>
wrote:
|Wes,
|Actually I have used this configuration.... (Storage Batteries in parallel)
|Back when cars were still 6 volt. Living in a cold winter climate I decided
|to use two dissimilar 6 v. batteries in series to start my truck on cold
|winter mornings using some relays and solenoids, paralleling them when not
|starting, charging them together. Worked fine the first day. The next
|morning they were both almost completely drained. After checking and
|rechecking my circuits this continued until I added a switch to disconnect
|one battery from the charging system when idle and connecting it only while
|the truck was running. Walla ! solved the problem and worked great except
|when I forgot to flip the switch when parking overnight. I devoted some time
|and effort to find out why this had occurred and passed what information I
|gathered along. If you have real experience with this situation, I would be
|interested in your results. In theory, both theory and practice work. In
|practice theory doesn't always cooperate.
I understand what you were doing, but without seeing a schematic of
the way you did it I cannot understand totally what the problem was.
Are you sure that one of your solenoids/relays wasn't energized in the
off (not running) condition.
Solenoids that handle the currents you were dealing with (particularly
on a 6V system) draw considerable coil current and could discharge the
batteries if left energized for long periods. If your added switch
(the "cure") was also disconnecting this parasitic load, then that is
the answer to your problem.
Otherwise, there is no reason why having two (or more) functional
batteries in parallel will increase the self-discharge rate. My
travel trailer used to sit for months at a time with two deep-cycle
12V batteries in parallel without charging. The trailer has a
built-in charger of very poor design that didn't properly maintain the
charge and also generated huge amounts of radio-frequency
interference, so it was usually turned off. I have since designed and
built a "smart" three step charger that is electrically quiet and can
be connected indefinately.
I need to build another one to maintain the battery in my '99 Camaro,
which goes dead while it is parked and we are traveling in the RV.
There is apparently a substantial parasitic load from the ECM and
anti-theft system that discharges the battery. After the last 3-month
trip, I had to replace the battery.
Wes
> > Don't do it.... Storage batteries have an internal resistance factor that
> > will discharge another battery connected in parallel unless they are exactly
> > equal in every way. difficult to achieve even if they are new identical
> > batteries. They will discharge each other.
>
> Telco's run multiple cells connected in series to make up a "string" of the
> required voltage. "Strings" are then paralleled to provide the required
> amp/hour rating desired. The battery strings, rectifiers and load all connect
> to a common buss. They do not use isolators. IIRC the cells we're now using
> were installed in 1973.
>
> A typical installation is pictured on page 5 of the following:
>
> http://power.tycoelectronics.com/pdf/round-cell-batteries.pdf
A roomful of telco batteries that last for decades, "only need water every
10-15 years" and cost kilobucks is a very different beast than two car
batteries in a basement.
Larry -- this issue is known, understood, and -solved-. Use an isolator.
Max
On Fri, 7 May 2004 17:39:33 -0500, "Bernard Randall"
<[email protected]> wrote:
[SNIP]
|If you need a more detailed discussion of parallel batteries have a look at
|this link,
| http://www.amplepower.com/pwrnews/parallel/, it doesn't outright condem
|parallel connection, but it does show that the problem is not as clear as
|Wes would like us to believe and is very dependent on the type of batteries
|used.
Thank you so much for providing this link, although I was already very
aware of Ample Power's web site. You clearly read things differently
than I. To save the other readers from digesting this, and to put you
on point let's use *your* reference for further discussion.
Remember how you got your panties all bunched up about cell shorts?
Ample Power (your reference, remember) says:
"It is our opinion based on reference 1 and 2 that disastrous cell
shorts are not a major failure mechanism, and the consequences are, in
any case, no more than what happens during equalization. Since the
early 1960s when we designed our first battery charger, we have
witnessed no dangerous situation that resulted from a cell short."
End Quote
And
Quote:
"Up to this point, we have attempted to define the scope of the issue,
and examine the failure mechanisms and their consequences to parallel
configurations. We find *nothing alarming* (emphasis added) about such
practice in either liquid or sealed battery systems, as long as the
batteries are properly instrumented and prudently cared for. We do
favor sealed batteries over liquid batteries for parallel systems
because of the consistency of cell chemistry, and the fact that we
can't tamper with it accidentally. We don't promote an unlimited
number of batteries in parallel. One limit is indicated by the answer
to the shorted cell question that was asked above. There are other
features of parallel systems that *are attractive* (emphasis added)."
End Quote
Earlier you said:
|It is not good practice to directly connect batteries in parallel, as an
|earlier response stated batteries do have internal resistance and unless the
|batteries are exactly matched the higher charged battery will discharge to
|the level of the lower one.
To which I replied:
"So what? Be an optimist, the battery with the lower terminal voltage
has been *charged* to a high voltage. The *total AH capacity remains
the same except* (emphasis added) for the slight I^2R loss."
You replied:
|"Totally false."
But *your* reference says:
Quote:
"First, a parallel system allows more convenient sizes which yields a
greater range of systems. For instance, a 100 Ah battery can be placed
in parallel with a 200 Ah unit to obtain a total of 300 Ah. Charging
proceeds as expected, with each battery receiving its share of the
charge current, and *each reaching a full charge at the same time*
(emphasis added). On discharge, each battery supplies current
according to its relative capacity, and both batteries maintain the
*same percent depth of discharge* (emphasis added)."
End Quote
As I said before, I stand by my remarks.
Connect the frigging batteries in parallel and stop fretting about it.
On Thu, 6 May 2004 17:04:19 -0700, "Chipper Wood" <[email protected]>
wrote:
|Don't do it.... Storage batteries have an internal resistance factor that
|will discharge another battery connected in parallel unless they are exactly
|equal in every way. difficult to achieve even if they are new identical
|batteries. They will discharge each other. There is an isolator that is used
|in motor homes etc. that will solve this problem. It is 2 diodes that will
|allow current to flow out of each battery to a load (Your pump) only. It
|must have a current capacity large enough for the load intended. You will
|also require another isolator to charge them, Same idea, It will allow
|current to flow from the charger to the batteries only and not between them.
|Both isolators connected properly will allow normal function of double the
|battery capacity but prevent a cross connection between them. One battery
|connection can be commonly connected. There may be a combination unit
|available. Check with a RV. supply co.
I've seen this same misinformation given in rec.outdoors.rv-travel
several times. It is totally incorrect!
Battery isolators are used in RVs for only one purpose; to isolate the
"house" battery from the "starting" battery such that running down the
house batteries doesn't leave you stranded. *That* is the function of
the isolator.
Lets me offer this simple analogy for parallel batteries, because they
are nothing more than storage reservoirs for electrical energy.
Consider two buckets (A & B) of water sitting on the floor with a pipe
connecting them at the bottom. If you fill Bucket A, the level in B
will rise right along with it. Likewise, if you remove water from
either, the level of the opposite will drop the same amount. (The
height of both above the floor will be equal; the principle of the
water level)
Note that one bucket *does not* drain the other. Why on Earth should
it? Where would the energy go?
To extend the analogy to the isolator case, consider that you want to
water the garden with water from one bucket, but the other supplies
drinking water and you don't want to run out of that. The connecting
pipe is modified to include two one-way check valves. The water supply
that fills the buckets connects to the check valves so that water can
flow in, but not back to the supply. Water for the garden is taken
from Bucket A, but the check valves prevent the backflow of water from
Bucket B, thus preserving the drinking water supply.
The electrical equivalent of a check valve is a diode. Battery
isolators are nothing more than two of them connected such that the
charging system can fill (charge) both batteries simultaneously while
preventing separate loads from draining both.
Connect the batteries in parallel (+ to +, - to -) and don't worry
about it.
"larry in cinci" <[email protected]> writes:
>I know this is off topic but I have gotton so much information here I hope
>to get an answer. I have an in line emergency battery powered sump pump that
>will run about 5-6 hrs on a full charge. I wish to connect a second battery
>to double the pumping time but I am not sure of the proper wiring. Option
>number 1, I can hook the positive termimals together and the negative
>together just like jumpstarting a car. Or option number 2, I can hook the
>positive pump lead to battery 1 positive, then battery1 negative to battery
>2 positive, then pump negative lead to battery 2 negative. I don't know
>which way is better or if
>one way will give me 24 volts going to the pump which I sure don't want. Any
>help will be greatly recieved. Thank you all. Larri
You want to hook them up in parallel.
scott
Virtually all modern battery isolators are full bridge design and will have
4 terminals: batt 1, batt 2, load, and charger.
Art
"Chipper Wood" <[email protected]> wrote in message
news:[email protected]...
> Don't do it.... Storage batteries have an internal resistance factor that
> will discharge another battery connected in parallel unless they are exactly
> equal in every way. difficult to achieve even if they are new identical
> batteries. They will discharge each other. There is an isolator that is used
> in motor homes etc. that will solve this problem. It is 2 diodes that will
> allow current to flow out of each battery to a load (Your pump) only. It
> must have a current capacity large enough for the load intended. You will
> also require another isolator to charge them, Same idea, It will allow
> current to flow from the charger to the batteries only and not between them.
> Both isolators connected properly will allow normal function of double the
> battery capacity but prevent a cross connection between them. One battery
> connection can be commonly connected. There may be a combination unit
> available. Check with a RV. supply co.
> --
> Chipper Wood
>
> useours, yours won't work
>
> "larry in cinci" <[email protected]> wrote in message
> news:[email protected]...
> > I know this is off topic but I have gotton so much information here I hope
> > to get an answer. I have an in line emergency battery powered sump pump
> that
> > will run about 5-6 hrs on a full charge. I wish to connect a second
> battery
> > to double the pumping time but I am not sure of the proper wiring. Option
> > number 1, I can hook the positive termimals together and the negative
> > together just like jumpstarting a car. Or option number 2, I can hook the
> > positive pump lead to battery 1 positive, then battery1 negative to
> battery
> > 2 positive, then pump negative lead to battery 2 negative. I don't know
> > which way is better or if
> > one way will give me 24 volts going to the pump which I sure don't want.
> Any
> > help will be greatly recieved. Thank you all. Larri
> > --
> > larry in Cinci
> >
> >
>
>
Wire batteries in SERIES
John
On Thu, 6 May 2004 19:10:50 -0400, "larry in cinci"
<[email protected]> wrote:
>I know this is off topic but I have gotton so much information here I hope
>to get an answer. I have an in line emergency battery powered sump pump that
>will run about 5-6 hrs on a full charge. I wish to connect a second battery
>to double the pumping time but I am not sure of the proper wiring. Option
>number 1, I can hook the positive termimals together and the negative
>together just like jumpstarting a car. Or option number 2, I can hook the
>positive pump lead to battery 1 positive, then battery1 negative to battery
>2 positive, then pump negative lead to battery 2 negative. I don't know
>which way is better or if
>one way will give me 24 volts going to the pump which I sure don't want. Any
>help will be greatly recieved. Thank you all. Larri
>J. Clarke, a notorious bottom poster, wrote something at the
>bottom of a 7KB message that he was too damn lazy to snip.
And I got tired of scrolling my mouse wheel about half way
down and gave up.
C'mon dude, learn to snip.
Art
> Bernard Randall wrote:
>
> >
> > "Wes Stewart" <n7ws@_arrl.net> wrote in message
> > news:[email protected]...
> >> On Fri, 7 May 2004 17:39:33 -0500, "Bernard Randall"
> >> <[email protected]> wrote:
> >>
> >>
> >> [SNIP]
> >>
> >>
> >> |If you need a more detailed discussion of parallel batteries have a look
> > at
> >> |this link,
> >> | http://www.amplepower.com/pwrnews/parallel/, it doesn't outright condem
> >> |parallel connection, but it does show that the problem is not as clear
> >> |as Wes would like us to believe and is very dependent on the type of
> > batteries
> >> |used.
> >>
> >> Thank you so much for providing this link, although I was already very
> >> aware of Ample Power's web site. You clearly read things differently
> >> than I. To save the other readers from digesting this, and to put you
> >> on point let's use *your* reference for further discussion.
> >>
> >>
> >> Remember how you got your panties all bunched up about cell shorts?
> >
> > The reference I made to cell shorts was that the terminal voltage would be
> > lower with a cell shorted, I said nothing of any fire damage. What is the
> > result of this? Lower voltage and smaller capacity at the best, at the
> > worst a cell where it isn't a dead short but inhibits the cell from
> > properly charging but the internal resistance is sufficiently high to
> > inhibit the required current flow.
> > >
> >> Ample Power (your reference, remember) says:
> >>
> >> "It is our opinion based on reference 1 and 2 that disastrous cell
> >> shorts are not a major failure mechanism, and the consequences are, in
> >> any case, no more than what happens during equalization. Since the
> >> early 1960s when we designed our first battery charger, we have
> >> witnessed no dangerous situation that resulted from a cell short."
> >>
> >> End Quote
> >>
> >> And
> >>
> >> Quote:
> >>
> >> "Up to this point, we have attempted to define the scope of the issue,
> >> and examine the failure mechanisms and their consequences to parallel
> >> configurations. We find *nothing alarming* (emphasis added) about such
> >> practice in either liquid or sealed battery systems, as long as the
> >> batteries are properly instrumented and prudently cared for. We do
> >> favor sealed batteries over liquid batteries for parallel systems
> >> because of the consistency of cell chemistry, and the fact that we
> >> can't tamper with it accidentally. We don't promote an unlimited
> >> number of batteries in parallel. One limit is indicated by the answer
> >> to the shorted cell question that was asked above. There are other
> >> features of parallel systems that *are attractive* (emphasis added)."
> >>
> >> End Quote
> >>
> >> Earlier you said:
> >>
> >> |It is not good practice to directly connect batteries in parallel, as an
> >> |earlier response stated batteries do have internal resistance and unless
> > the
> >> |batteries are exactly matched the higher charged battery will discharge
> > to
> >> |the level of the lower one.
> >>
> >> To which I replied:
> >>
> >> "So what? Be an optimist, the battery with the lower terminal voltage
> >> has been *charged* to a high voltage. The *total AH capacity remains
> >> the same except* (emphasis added) for the slight I^2R loss."
> >>
> >> You replied:
> >>
> >> |"Totally false."
> >>
> >> But *your* reference says:
> >>
> >> Quote:
> >>
> >> "First, a parallel system allows more convenient sizes which yields a
> >> greater range of systems. For instance, a 100 Ah battery can be placed
> >> in parallel with a 200 Ah unit to obtain a total of 300 Ah. Charging
> >> proceeds as expected, with each battery receiving its share of the
> >> charge current, and *each reaching a full charge at the same time*
> >> (emphasis added). On discharge, each battery supplies current
> >> according to its relative capacity, and both batteries maintain the
> >> *same percent depth of discharge* (emphasis added)."
> >>
> >> End Quote
> >>
> >> As I said before, I stand by my remarks.
> >>
> >> Connect the frigging batteries in parallel and stop fretting about it.
> >
> > In the paragraph you quoted above I believe you will find that they are
> > refering to two batteries of different a/h capacity, not a situation where
> > either battery is in fault condition whether it be one cell is high
> > resistance or shorted. In either of those cases their a/h capacity is
> > totally unknown. Or are you claiming that you can predict the a/h
> > capacity of a damaged cell??
> >
> > This thread is discussing the situation as it applies to a sump system
> > which
> > appears from the supplied information to be unattended. You claim to be
> > an EE, all the experienced engineers I have worked with don't look at
> > situations through rose colored glasses as you appear to advocate. Anyone
> > with an engineering background will have to take into account what happens
> > in the fault condition of a critical piece of equipment. In this case the
> > battery is one of those items. As I said in my initial post, and now
> > expand, if it is a critical application I would use 2 batteries with
> > separate chargers and a differential relay to auto change the batteries
> > when the first reached its rated dischage voltage.
>
> He's not looking for a solution for "a critical application", he's looking
> for a longer run time on a system that is working satisfactorily with a
> single battery. He's not dealing with a discharged or damaged battery,
> he's dealing with two batteries both of which will unless something
> malfunctions be fully charged and in equilibrium at the start of operation.
> Thus none of your concerns apply and I don't really understand why you're
> on about this.
>
> > Bernard R
>
> --
> --John
> Reply to jclarke at ae tee tee global dot net
> (was jclarke at eye bee em dot net)
On Fri, 7 May 2004 11:27:44 -0500, "Bernard Randall"
<[email protected]> wrote:
|
|"Wes Stewart" <n7ws@_arrl.net> wrote in message
|news:[email protected]...
|> On Thu, 6 May 2004 17:04:19 -0700, "Chipper Wood" <[email protected]>
|> wrote:
|<snip>
|> I've seen this same misinformation given in rec.outdoors.rv-travel
|> several times. It is totally incorrect!
|>
|<snip>
|> Lets me offer this simple analogy for parallel batteries, because they
|> are nothing more than storage reservoirs for electrical energy.
|> Consider two buckets (A & B) of water sitting on the floor with a pipe
|> connecting them at the bottom. If you fill Bucket A, the level in B
|> will rise right along with it. Likewise, if you remove water from
|> either, the level of the opposite will drop the same amount. (The
|> height of both above the floor will be equal; the principle of the
|> water level)
|>
|> Note that one bucket *does not* drain the other. Why on Earth should
|> it? Where would the energy go?
|>
|
|<snip>
|> Connect the batteries in parallel (+ to +, - to -) and don't worry
|> about it.
|>
|
|It is not good practice to directly connect batteries in parallel, as an
|earlier response stated batteries do have internal resistance and unless the
|batteries are exactly matched the higher charged battery will discharge to
|the level of the lower one.
So what? Be an optimist, the battery with the lower terminal voltage
has been *charged* to a high voltage. The total AH capacity remains
the same except for the slight I^2R loss.
|If you don't believe it do the Kirchoff
|analysis.
Oh please, I'm a retired EE, don't try to baffle me with big words.
|In emergency situations batteries are connected in parallel, such
|as when jump starting a car, but as you will notice there is an ititial
|spark and heavy current flow from the donor battery trying to charge the
|dead one.
So what? *You* do a Kirchoff analysis and tell us why this surprises
you.
|
|The analogy of the two water buckets doesn't hold water in this case because
|you overlook the connection between the individual cells of the batteries.
That's why they're called "batteries", they are a collection of cells.
I didn't overlook anything of the sort. But if this baffles you,
change "batteries" to "single cells" and connect them in parallel.
The charge/discharge analogy continues to "hold water."
|One cell can becomes high resistance, quite common, in which case the
|capacity of that battery becomes virtually zero;
So what? If it has high internal series resistance, it becomes less
of a voltage source and more of a current (limited) source. So it may
not contribute to the load current, but it certainly doesn't detract
from it either. The *high internal resistance* sure the hell isn't
discharging anything, as was the misguided concern of the post to
which I originally responded.
|or if a cell partially
|shorts, due to buckling of the plates or sediment shorting the plates, in
|which case the battery terminal voltage drops.
So what? A failure can occur in a stand alone battery too. I guess
that means we shouldn't use batteries; they might fail afterall.
|
|In professional installations the solution would be two batteries controlled
|by a differential relay so when the first battery drops to its rated
|discharge voltage it would be dropped from circuit and the second connected.
|In this application the diode isolators would probably be the best
|alternative.
There are millions of RVs running around (one of them parked outside
my house) and who knows how many solar energy installations that are
using many multiples of parallel connected batteries. Do failures
ever occur? Sure, usually from abuse in the charge/discharge cycle,
but *not* because there is something inherently wrong with parallel
connections. See:
http://www.trojan-battery.com/technology_connection.htm
I stand by my earlier remarks.
Option 2 will likely burn out your pump as it will deliver 24V to it.
Option 1, parallel, is the way to do it. However it could shorten the
battery life due to circulating currents between the batteries.
The best solution is to get a battery isolator from an RV or boating
supply house and hook the batteries up thru it.
Art
"larry in cinci" <[email protected]> wrote in message
news:[email protected]...
> I know this is off topic but I have gotton so much information here I hope
> to get an answer. I have an in line emergency battery powered sump pump that
> will run about 5-6 hrs on a full charge. I wish to connect a second battery
> to double the pumping time but I am not sure of the proper wiring. Option
> number 1, I can hook the positive termimals together and the negative
> together just like jumpstarting a car. Or option number 2, I can hook the
> positive pump lead to battery 1 positive, then battery1 negative to battery
> 2 positive, then pump negative lead to battery 2 negative. I don't know
> which way is better or if
> one way will give me 24 volts going to the pump which I sure don't want. Any
> help will be greatly recieved. Thank you all. Larri
> --
> larry in Cinci
>
>
Do you really believe that?
"Mark Hopkins" <[email protected]> wrote in message
news:[email protected]...
> Wire them together using Option one, but instead of hooking the pump
> directly to one battery, put the positive from the pump on one battery and
> the negative from the pump on the other battery. That way, the bank will
> appear to the charger and pump as one huge battery and you will eliminate
> the problem of discharging one battery instead of both.