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Join Date: Aug 2009
Posts: 65

36 Volts From 6ea 12 Volt Batteries

10/12/2009 11:02 AM

I intend to replace 6ea 6 volt batteries, which are series connected,outputting 36 volts, with 6ea 12 volt batteries.There are a couple of ways to connect the 12 volt batteries to obtain 36 volts output.The first way is to parallel the 12 volt batteries into 3 pairs, then series the 3 pairs into 36 volts out.The second way is to series 3 of the 12 volts battereis into two groups of 3 each, then parallel the outputs of 36 volts.

I plan to use the original charger designed for 6ea 6volt batteries(36 volts).

What are the pros and cons of each method as pertains to charging and power output.

Will I encounter problems with imbalanced charging with either method?

The original 6 volt batteries are 105 amp hours each,and the 12 volts are 100 amp hours each.

thanks

eztreet

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#1

Re: 36 volts from 6ea 12 volt batteries

10/12/2009 12:05 PM

It is 6 of one, and a half dozen of the other. Arrange them so as to use the shortest cables. It will work either way. Good luck.

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#2

Re: 36 Volts From 6ea 12 Volt Batteries

10/12/2009 11:43 PM

I work for a battery manufacturing company. My suggestion: Fist make three pairs by close matching of voltages/ capacities then series connect.

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Subramanyam
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#3

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 3:08 AM

EZStreet,

The 6 Six Volt 105Ah batteries in series are about equal to the 3 Twelve Volt 100 Ah batteries in series. 6 6 Volt batteries contain 18 cells. 3 12 Volt batteries contain 18 cells.

6 Twelve Volt batteries connected in series parallel to provide 36 Volts will give you 200 Amp Hours and the recharging rate will be different so the original charger may not be adequate.

As mentioned by Subramanyam in posting #2; Mismatched batteries connected in parallel tend to fight each other due to the difference in voltage. You would have to buy special matched batteries for the pairing to prevent one from drawing current from the other to equalize.

You can isolate the two banks from each other using an isolator.

You can draw power through the Isolator and when no power is drawn the two banks don't interfere with each other. You can maintain or charge the batteries at the same time you draw power.

Jon

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#5
In reply to #3

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 7:00 AM

Regards

A good reply .A GA is yours

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#8
In reply to #5

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 2:16 PM
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#6
In reply to #3

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 8:11 AM

Thanks for the info.The batteries are deep cycle fiberglass mat 100 amp hour from a UPS, so they are well matched.What type diode do you recommend for isolation?It looks like the charger diodes will carry the full current of the charger, and the load diodes will carry the full load amperes(1/2 load on each).This is for a golf cart, so the load will be hundreds of amps at times.

Stud mount diodes on a heat sink for load diodes comes to mind.

I can build the isolator if I know the specs.

Thanks

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#4

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 6:43 AM

In such a configuration, make sure that you NEVER ever run any single battery down, or overcharge one, otherwise you will be forever buying new batteries......make sure none ever gas either, that is just as bad.

My best info for you is the following:-

1) Buy a total output of battery power at least twice of what you need.

2) Have a voltmeter installed to make sure that you never go under 36 volts or 12 volts per 12 volt battery. Even if you follow point 3) below, its still better....

3) Only use Leisure batteries, they can handle deep discharge better.

4) Never charge above 13.8 - 14 volts per 12 volt battery. That causes gassing, bad for batteries and marital partners....

5) Do not buy car type batteries......they collapse first.....

6) I would not use SLA batteries either. More money for no gain. They last no longer.

7) There are small electronic "regenerators" that go across each 12 volt battery and help the battery to NOT sulphate up.....they give the battery a high voltage "jolt" every few seconds. Install one on each battery. Cheap ones that work just as well can be made or bought.

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#7

Re: 36 Volts From 6ea 12 Volt Batteries

10/13/2009 10:41 AM

I have given some thought to charging and I feel that the best method is 3 LA intelligent chargers, each one connected across 2 x 12 volt batteries in parallel. The batteries can remain in circuit, 2x 12 in series with each other, of the 2 x 12 batteries....

Cheaper and easier to buy chargers and the charge will be better distributed to only two bats in parallel, less damage to any of the batteries over long periods....

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Andy Germany (2); bob c (1); EZStreet (1); Haajee (1); kudukdweller9 (2); kvsubramanyam (1)

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