I have 4 strings of 4x65AH battery's can i ad a string of 4x100AH battery's to increase the total capacity for my ESS system MultiPlus II 48v 3000VA
The battery's a SUN Battery SB12-65 (12V65AH) and SB12-100 (12V100AH)
asked
Parallel 65AH and 100AH battery in 48v ESS system
If my maths is correct, you have 16 x 65Ah batteries? Stringed up as 4p x 4s ??
I do not see why not.
You have to make sure that they are at the same SOC when connecting them in parallel.
Edit:
The discharge current of such parallel system should be adjusted to the smaller battery in this parallel setup.
I would agree with @MarekP, this would work and Pylontech actually allows this config but I would be hesitant to do it without a BMS. I would do it if you maybe install a Victron Battery Balancer to make sure the 2 strings stay balanced but that means you would need 6 balancers.
Hi @shaneyake
Author has a AGM batteries and they do not need BMS.They would benefit from battery balancers.
He would need 15 battery balancers for his 12V AGM batteries. (12 for 65Ah sets and 3 for new 100Ah set)
Hi Jens-Due, in my opinion, this is a very bad idea. The batteries not being of the same capacity, it will create an unbalance between the batteries, and creating also issues with the cabling and charging. You will toast the smaller batteries as the mppt will continue to charge (unable to get the real picture of the SOC).
Michel
Can you explain how MPPT would toast the smaller battery?
SOC of those batteries is judged by its voltage.
Two batteries, regardless of their size, connected in parallel have the same voltage.
