Two 'Chinese' batteries in parallel...

[radiomean]

Hi, I have a Growatt SPH5000 and GBLI6532 battery, which is 6.5kWh storage.. I've recently added two 'random Chinese' batteries in parallel - the individual batteries are about 3.2 kWh each so I've essentially doubled my battery storage to 12.6kWh ish...

The two new batteries are connected in parallel with short leads between them (25cm or less) then in parallel to the GBLI6532 using 35mm(2) cables, about 2m long.
This system generally works well, but the GLBI6532 discharges to 10% and the Chinese batteries discharge to about 15 to 18% - as the cable from the Chinese battery to the invertor is 2m long, but the cable from the GBLI6532 to the invertor is only about 30cm, I think this makes sense...

However, the two Chinese batteries discharge to around 15% for one and 18% for the other. I wondered if I connected them differently that they would discharge equally? See below - I initially connected them as on the left, but I wondered if I connected them as on the right, they would discharge completely evenly? As connected on the left, battery two has longer cables, higher cable resistance and would theoretically discharge a bit less?

Thanks!

PS thinking this through a bit more, I suppose I ought to connect the Growatt battery with 2m of leads also (as opposed to the short 30cm of lead currently), which might even out the discharge?

 

[Mattb4]

The leads between pos and neg should be the same length and the leads going to your inverter should connect as in your right hand drawing. The positive to one battery the negative to the other.

 

[radiomean]

The leads between pos and neg should be the same length and the leads going to your inverter should connect as in your right hand drawing. The positive to one battery the negative to the other.

Thanks... I had (belatedly!) worked that out but it's good to get confirmation. If you have three or four batteries in parallel, the wiring must get a lot more complicated to achieve equal lengths...