24v parallel batts: 2" difference OK?

[solarstuff]

Hi folks,

I am adding a second 200a 24v battery in parallel to my 24v Growatt 3000 (also 200a, both lifepo4, both 200a BMS).

My last two 2/0 cables in the house have just under 2" difference in length (12 and almost 14"). And no more lugs to cut and re-crimp.

Will even this difference mess up balancing between the two batteries or is it safe to proceed?

Thx for reading.

 

[DIYrich]

I wouldn't worry about 2". You could swap one of the longer cables for the shorter one. Then both batteries would have equal circuit length (one long, and one short).

 

[solarstuff]

I wouldn't worry about 2". You could swap one of the longer cables for the shorter one. Then both batteries would have equal circuit length (one long, and one short).

These cables would be neg to neg and pos to pos: the existing cables up to inverter are 1awg (size limit of the growatt).

Still OK to he a little under 2" off on this parallel connection?

 

[TacomaJoe]

You should also move one of the inverter cables to the new battery to give the bank a diagonal connection.

 

[solarstuff]

You should also move one of the inverter cables to the new battery to give the bank a diagonal connection.

Diagonal to fuse above, exactly.

So I'm worrying about nothing re: a 1.8" difference on a length of less than 15"?

 

[TacomaJoe]

In my scenario, 2 batteries, diagonal connection, let's say 200A going to the inverter. The 12" cable drops 240mV and the 14" cable drops 280mV giving battery A 40mV difference from battery B. These voltage drops are a total guess for illustrative purposes. Next point is that the 40mV difference is at 200A, when the current drops so does the difference. Take away the load and the batteries will settle to the same voltage.

 

[DIYrich]

Diagonal to fuse above, exactly.

So I'm worrying about nothing re: a 1.8" difference on a length of less than 15"?

I would worry more about the 1 awg vs 2/0. That is a big difference. Diagonal connections would resolve that.

Same length presumes same awg.