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stocksy asked

Connecting Lithium Batteries in Parallel

Hi,

I have a 400ah lithium bank (3x 100ah) and would like to increase this to 600ah (6x 100ah). The advice I got when installing this was to make sure that all cables to the busbar went directly to each of the batteries positive and negative terminal and that the cables were of the exact same length. This is to insure that all the cells remain perfectly in balance, which it does. My issue now is that I only have 4 connections on my busbar. My plan is to group the batteries into 3 lots of 2 to make 3x 200ah batteries and, for each group of 2, run the positive from one of them and the negative from the other to the busbar. Would that work and keep the cells balanced or do I need to run cables to the busbar from each of the 6 batteries independently?

Sorry - I have no drawing software, but hope this makes my plan more visual:

Positive busbar terminal <----->Batt1 <----->Batt2<------>Neg busbar terminal

Positive busbar terminal <----->Batt3 <----->Batt4<------>Neg busbar terminal

Positive busbar terminal <----->Batt5 <----->Batt6<------>Neg busbar terminal


Thanks,

Michael

battery chargingLithium Battery
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russ avatar image russ commented ·

If I understand what you propose, you will have each pair of batteries in series, doubling the voltage. Are your current 4(?) like that? Otherwise you will destroy the multi.

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ejrossouw answered ·

@stocksy I'd check with the battery manufacturer first if they have recommendations, especially if the batteries are equipped with an internal BMS, but it does not seem to be.

I don't simply want to just give an answer and recommend below read to better understand what you are doing and not just executing a set of instructions. Hope this helps.

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

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stocksy avatar image stocksy commented ·

Thanks - that's a great document - very useful info! Just done the voltage drop test and happy that I'm below the 0.3v recommendation for 12v system :)

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