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silverfox asked

Isolator for VE CAN in Cerbo GX recommendations - Is there a CANBUS isolator?

I want to connect a non-listed BMS to my Cerbo GX using the VE CAN bus port (or the BMS-CAN port). My BMS (JK BMS, now a very common unit) lives on the negative battery cable. Since the Cerbo GX CAN ports are non-isolated, I can forsee a condition where the BMS might shut off battery negative and the battery positive will try to 'find its way' back to battery negative through the communication cable connecting the BMS CAN bus to the Cerbo GX CAN bus. Through the GND or maybe the CANL wires. In any case, using an opto isolator of some kind just seems like good safety practice to protect the cables and the Cerbo GX.

Is there a recommended adapter board or something already available to do this easily? All I want is a 'CAN Bus Isolator' or some such but so far I haven't found much.

Such a device might need to be powered from both sides - I could certainly get two power supplies to run such an isolator if necessary - one would be a 48 to 5v DC to DC converter (on the battery side) and the other from any of many voltage sources on the Cerbo GX side of my system.

cerbo gx
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2 Answers
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Meine_Energiewende answered ·

As far as i know there is no driver for the CAN version of JK BMS. The serial version is isolated on bms side and works quite well.

Jens

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silverfox answered ·

@Meine_Energiewende Thank you for your reply.

I watched some of Andy's (off-grid-garage) youtube videos where he interfaces the JK BMS with his Raspberry Pi, and says it all applies to the Cerbo GX also. And there is

https://github.com/Louisvdw/dbus-serialbattery

I just thought the CAN bus implementation would be easier.

I have 3 JK BMS's, each controlling one 16s bank of batteries, nominal 48V each.

I also have an older server-rack system, which has RS485 ports in each of 5 separate modules, with little or no manufacturer support or documentation. I thought if I convert those RS485 ports to CAN bus I could run all of them and the (3) JKs on one CAN bus to the Cerbo GX.

Maybe you have some ideas here? Thanks!

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