question

Hi @langerWaldi

I have a similar setup however i opted for a smart shunt rather than trying to get communication setup between JKBMS and Victron, as when i was settings my system up (awhile ago) the information online for setting communication up between JK BMS and victron was minimal.

1. It wont really matter too much, if you had a smart shunt the SoC would calibrate overtime based on settings you input into the smart shunt. However if you've got JK communication setup then SoC should be part of that communication. If your question is more around safety. ie what will happen if JK communication isnt working straight away, will Multiplus overcharge battery etc then no because the multiplus will know the voltage, so as long as your VeConfigure settings are correct then you'll be fine without SoC straight away. It'll just be a nuisance not knowing accurate SoC.

2. In your setup SoC will come from JK BMS once configured. If not configure then victron system wont know SoC. (hence the need for smart shunt or BMS communication).

3. The BMS itself i believe has a shunt in it, so if communication is setup (and working) then no you dont also need a victron smart shunt as well as SoC will be passed from the BMS.

Thanks a lot Matt for this very helpful, detailed and very quick response. Very much appreciated!
I will now look up the communciation protocol of JK to see if SOC is included (and try to get in run ;-)
Otherwise I would go for Victron Smart Shut, although I don't like the idea to have two devices (shunt and JK BMS) in the high current path ...
Thanks again!
Best regards,
Josef

Hi @langerWaldi, no worries at all. I'm almost certain it will include SoC data.

Someone please correct me if I'm wrong here but I don't believe JK BMS communication is supported natively by Victron, you need to install additional community made drivers (I think it's called dbus serial battery on GithHub). Unless native support has been added recently.

I wouldn't worry too much about adding a second device in high current path as long as everything is well within their ratings. It's all designed to be installed that way anyway. I believe the smallest smart shunt available is rated for 500a. Which I imagine is well above the current you'll be drawing from your battery (and also likely above BMS rating).

I've had a similar setup running for about 12months now, with no issues. Took me awhile to perfect my smart shunt settings but it's been pretty spot on with SoC since I've finally found what works.

If you do go the JK BMS communication route there's a youtube channel called OffGridGarage that has a video installing the drivers and setting up communication. He also discusses the pros/cons of BMS communications vs smart shunt. Really good channel for DIY LiFePO4 in general. I believe he still uses a smart shunt in his setup, however he often changed BMS to test them.