this post was submitted on 05 Jul 2025
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Hello. I recently bought an off-grid house with its own solar system. So I'm learning little by little. Right now, I have a Voltronic Axpert VMIII inverter connected to two battery banks. These battery banks have 16 batteries each, totaling 32 batteries (LiFePO4). Each bank has a BMS model JK B2A20S20P. There is no communication between this inverter and the BMS; everything works based on voltages, meaning I have told the inverter what voltage it should have. I am going to upgrade my installation with more panels, a Victron MultiPlus-II 48/10000/140-100 inverter, a Victron Cerbo GX MK2, a VICTRON MPPT 250/100-Tr VE.Can, a VICTRON MPPT 250/70-Tr VE.Can, and some other things that I don't think are important right now. My doubts arise about whether it will be possible to connect the BMS of the battery banks to the Victron system so that it can manage the batteries correctly, or if it is better to buy new BMS that do allow this. What do you think?

If I should buy a new BMS, which one do you recommend for this case?

Thank you very much!

Edit: Added type of batteries Edit2: I'm from Spain

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[โ€“] [email protected] 1 points 4 days ago (1 children)

What type of batteries?

The MultiPlus can act as a solar charge controller, do you need the extra MPPT devices for added capacity?

I'd leave the BMS until you get everything set up. To my knowledge, the only advantage of having the MultiPlus talk to the BMS is to get state-of-charge information, which you can also get from a shunt.

The Victron gear should just give the BMS's all they can and let the BMS do the limiting once the batteries are full.

I don't have any experience with JK BMS's but they have RS485 so they should be able to talk to the MultiPlus. I'd wait for a better answer from someone more knowledgeable, or see if you can find the answer in the Victron manual. Maybe YouTube has some info. The OffGridGarage channel has a lot of Victron/JK content.

[โ€“] [email protected] 2 points 4 days ago

The MPPTs have been recommended to me, as I will have different strings of panels from different brands and power ratings. I was thinking of buying a Can to RS485 cable and see if it works with the current BMS, but I was looking for some information first. Regarding the type of batteries, I have added them to the post.