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FoxESS V1 BMS protocol

Posted: Sun Feb 12, 2023 8:42 pm
by Can
Users who wish to decode the can bus messages sent between the BMS and inverter can find a suitable dbc file here: ... bc_codegen

When used in conjunction with a can bus sniffer (SavvyCan), this file will decode each can message into human-readable values. A collection of can bus tools for every OS is available here: ... /

V1 protocol provides minimal information from the battery stack but includes charge and discharge rate, SoC, temps, slave voltages, and so on. In response, the inverter provides datetime every few seconds.

The newer V2 protocol provides individual cell data (voltage, temp) but this is not yet documented. If any users wish to contribute to this I can ship out all needed monitoring equipment with support. Alternatively, I can travel within NW UK.

Re: FoxESS V1 BMS protocol

Posted: Mon Feb 13, 2023 2:39 pm
by Dave Foster
That's an impressive and comprehensive piece of work, thanks for posting that - I've been thinking about logging and analyzing the CAN bus this will be extremely helpful.

When you refer to the v2 protocol, do you know what governs the v2 protocol being used? is it only when you upgrade to a V2 BMS or as a result of the upgrade to the latest inverter master/slave/battery firmware combinations (with or without v2 BMS)

Re: FoxESS V1 BMS protocol

Posted: Mon Feb 13, 2023 5:31 pm
by Can
V2 is a knowledge void for me. I can only demonstrate what I know based on how my own kit presents (fw < 1.50).

There are two communication buses at play here, master to inverter and master to slaves. I do not have any information on the latter.

I'm happy to look at the V2 in detail but I need can traffic dumps as a bare minimum. My suspicion is the cell level data is contained in 0x1881 & 0x1882, needs to be confirmed though.

Re: FoxESS V1 BMS protocol

Posted: Sat May 13, 2023 10:02 am
by MB
I don't know whether this topic is the right place to add a query.

I'd like to interrogate the state of health of an ECS 4100 battery pack, prior to connecting to the inverter. Is the software available to perform this task. The inverter had a dead short, and was replaced, however the system is not working.

Therefore would like to determine whether the battery pack is healthy.

Would this topic be the appropriate place to place this query?

Re: FoxESS V1 BMS protocol

Posted: Sat May 13, 2023 12:24 pm
by Can
Probably best to open a new post.