# Paralleling a Volt 24v module



## Windydrew (Dec 18, 2015)

Needing to confirm that my idea to take a 24v module and parallel cells to make it 12v nominal. Would this work? What would be the best way? I was thinking of attaching a wire from the center of the module to the end on the positive and negative ends respectively.


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## rwaudio (May 22, 2008)

Windydrew said:


> Needing to confirm that my idea to take a 24v module and parallel cells to make it 12v nominal. Would this work? What would be the best way? I was thinking of attaching a wire from the center of the module to the end on the positive and negative ends respectively.


Technically possible but first you must CUT the existing series connection between cell 6 and 7. Then find a suitable way of attaching wires to the new end points (cell 6+ and cell 7-), you would then connect 7- to the main negative and cell 6+ to the main positive and use those large main terminals to connect to the load. Make sure the wires you use to go from 6+ and 7- to the main terminals are rated for more than half the desired total load.


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## Windydrew (Dec 18, 2015)

rwaudio said:


> Technically possible but first you must CUT the existing series connection between cell 6 and 7. Then find a suitable way of attaching wires to the new end points (cell 6+ and cell 7-), you would then connect 7- to the main negative and cell 6+ to the main positive and use those large main terminals to connect to the load. Make sure the wires you use to go from 6+ and 7- to the main terminals are rated for more than half the desired total load.


I wonder if I could drill out the spot welds and put an insulating material in between. Then I could run a bolt through to connect it up. I'm thinking I'll use some of the volt bus bar to build this. I'm wanting a starter battery to use in my vehicles.


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## piotrsko (Dec 9, 2007)

It will be simpler to just cut the cell interconnection

By bus bar do you mean 
Module interconnects or the orange covered ?

And at 45 ah you'll need 3-4 modules to about equal a starting battery.


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## Windydrew (Dec 18, 2015)

piotrsko said:


> It will be simpler to just cut the cell interconnection
> 
> By bus bar do you mean
> Module interconnects or the orange covered ?
> ...


The research I've done says a li-ion battery ah is equal to 2 lead acid ah.I think 1 module paralleled will be plenty for most vehicles. 
I guess I wasn't picturing it right, cutting down the middle of the u makes more sense for sure.
Ya, reusing the orange covered bus bar, since I have no other use for it. The heavy amp draw only lasts a few seconds so I think it would be sufficient. I'll let you guys know.


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## Yabert (Feb 7, 2010)

Windydrew said:


> The heavy amp draw only lasts a few seconds so I think it would be sufficient. I'll let you guys know.


It will be easily sufficient because your "12v" and 90Ah battery will output way over 1000 Amps and stay over 14v during a short discharge time.
But do you realise this 12v battery build with the Volt cells will be a 15v nominal battery (16,8v full charge)?
Do you plan to drive the car without alternator? Or do you plan to disconnect the battery after you started the car?


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## rwaudio (May 22, 2008)

Yabert said:


> It will be easily sufficient because your "12v" and 90Ah battery will output way over 1000 Amps and stay over 14v during a short discharge time.
> But do you realise this 12v battery build with the Volt cells will be a 15v nominal battery (16,8v full charge)?
> Do you plan to drive the car without alternator? Or do you plan to disconnect the battery after you started the car?


That would be 4S Yan 

With 3S it probably wouldn't be safe to charge from a stock alternator.
11.1v nominal, 12.6 fully charged. It would start a car no problem, but overcharge it too much and your car goes down in a spectacular ball of flame.


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## Yabert (Feb 7, 2010)

Right, 3S. My error.
So.... your 12v and 90Ah battery will output way over 1000 Amps and stay over 10v during a short discharge time.

This stay relevant.


Yabert said:


> Do you plan to drive the car without alternator? Or do you plan to disconnect the battery after you started the car?


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## Windydrew (Dec 18, 2015)

Yabert said:


> Right, 3S. My error.
> So.... your 12v and 90Ah battery will output way over 1000 Amps and stay over 10v during a short discharge time.
> 
> This stay relevant.


I'll use a bms and contactor to shut it off when charged.


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## Windydrew (Dec 18, 2015)

Windydrew said:


> I'll use a bms and contactor to shut it off when charged.


Maybe I could use the 48v module to do 4s6p? That would be a strong 12v battery, probably overkill


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## rwaudio (May 22, 2008)

Windydrew said:


> Maybe I could use the 48v module to do 4s6p? That would be a strong 12v battery, probably overkill


I guess an important question is do you already have Volt modules on hand and you are just looking for a use for them? Looking to buy them for this purpose?

If you don't already have it, LiFePO4 (4S) is a much more suitable replacement for a cars 12v battery.
You might still want a BMS but you can charge it to 14-14.6v and discharge it to 11-12v much like a lead acid battery. (just don't charge it when it's cold)


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## Windydrew (Dec 18, 2015)

rwaudio said:


> I guess an important question is do you already have Volt modules on hand and you are just looking for a use for them? Looking to buy them for this purpose?
> 
> If you don't already have it, LiFePO4 (4S) is a much more suitable replacement for a cars 12v battery.
> You might still want a BMS but you can charge it to 14-14.6v and discharge it to 11-12v much like a lead acid battery. (just don't charge it when it's cold)


Yes, I have a Volt pack sitting here and no method to charge them as of right now. I would like to use the whole pack in my mini sprint car, but space and weight are going to prohibit it I believe. So I have 2 48v and 1 24v module spilt just waiting for me to do something.


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## Windydrew (Dec 18, 2015)

What about doing a dc buck converter and stepping the voltage down to 12v, then it could back feed the battery at the right voltage while running from the alternator.


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## Windydrew (Dec 18, 2015)

Windydrew said:


> What about doing a dc buck converter and stepping the voltage down to 12v, then it could back feed the battery at the right voltage while running from the alternator.


And instead of opening the battery when it gets charged, I could shut off the alternator when it's full and save gas


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