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I'm getting started on converting an MGB with a random Chinese EV subframe and a Zoe battery pack, I'm battling with the prospect of weather or not I'll be able to use the integrated Zoe BMS or not depending on my pack layout (unsure if I can fit the whole pack in the enginebay/transmission tunnel) so I've been eyeing up some modular bms's for a split pack configuration.

Most of these seem woefully expensive (£1500 BMS for a £500 battery seems crazy) or Chinese and still kinda expensive. I stumbled across the open inverter BMS and it seems like a good option, but the only thing mentioning cascading modularity is a single line on the listing and a single paragraph on the wiki. It also says 'firmware isn't finished" elsewhere, so what I wanted to understand is is it useable? Can it do split pack battery boxes? Does it have everything needed to control an EV battery already built in? (Contactors control, pre charge control, charging ect), in addition what is the restocking like? I see there's 5 units but I would need 6 (8 cell pairs per module, one BMS per pair of modules) and I don't want to commit to a system that might take years to restock, it's tricky to guage active development.

I'm also VERY interested in the CCS control board, I don't want an EV I can't drive anywhere far and the OG Zoe did 43kw AC on an air cooled battery so I'd be looking to match this with DC. Giving the current pack a half hour charge and the end goal pack about an hour, does this part work independently from the BMS, with any specific bms's or just the open inverter BMS, my point is I guess if I want to use this do I need to use the open inverter BMS?
Appreciate any direction on these matters

Hi and welcome!

thanks for your questions about the BMS. It seems the documentation needs updating. I'm assuming we are talking about this one? https://openinverter.org/wiki/16-cell_BMS
The OI BMS can be cascaded with 8 modules right now, also across multiple locations. 12V and CAN run in parallel to all modules and an enable signal runs as a daisy chain from module to module.
There are a few videos about it on my channel, this one being the latest:


And here's another one:


Restocking is done via JLCPCB, so that is quite stable.
The BMS does not do anything besides voltage, current and temperature sensing. So you'll need other means for contactor control.
The firmware is usable by now and offers most modern BMS features. SoH calculation needs to be refined and taken account for in SoC calculation but that's not a show stopper.

What? Doesn't zombieverter takes care of precharging and everything when used with OI BMS?

Zombieveryer doesn't list open inverter BMS as compatible!

johu wrote: ↑Sat Apr 11, 2026 6:53 am
The BMS does not do anything besides voltage, current and temperature sensing. So you'll need other means for contactor control.
The firmware is usable by now and offers most modern BMS features. SoH calculation needs to be refined and taken account for in SoC calculation but that's not a show stopper.

This sounds ideal, I'm wanting to try a MVP EV and like the idea of manual contactir control instead of automation, and alarms to inform of out of spec cells allerted by BMS. I also like how the unit costs is low, I can test/Dev with one or two then expand to full pack!

Lemlurker wrote: ↑Sat Apr 11, 2026 9:49 am Zombieveryer doesn't list open inverter BMS as compatible!

currently in the process of adding modules, might as well add that one

It's now in the Vehicles_Testing branch