We have an off-grid installation in our RV with LiFePO4 batteries along with a 3kVA Victron MultiPlus, CCGX and BMV-712. The behavior of the BMV-712 is such that if it loses power, it restores to 100% SoC when turned back on. I am aware of the setting so it is set to unsynchronized instead.
Unfortunately neither behavior is suitable for us - the most likely cause of loss of power to the BMV is the BMS temporarily cutting off the batteries due to excessive current. This is a temporary situation which we can restore from within about 1 minute, so the SoC of the batteries does not change meaningfully during this time.
My plan is to install a 12V Uninterruptible Power Supply (UPS) that is kept charged by the main batteries but provides reliable power to the BMV as well as a handful of other low power but key systems such as the TPMS booster and probably the CCGX. I have a Blue Sea Systems split fuse block and the UPS will power the bottom section for these devices.
We have recently acquired the temperature sensor to connect to the BMV-712, and this has two wires - essentially data and positive power. I'd like to connect it such that the data line goes into the BMV but power for the BMV comes from the UPS into the other connection on the BMV. The temperature sensor draws its power from the 12V positive terminal it connects to, but I will remove the fuse and not connect its power line to the BMV.
I have tested this by connecting it up and it all seems to work correctly. However, before I hardwire this in, I wanted to check to see if a) anyone can see any reason this wouldn't work in all cases (I haven't checked all failure scenarios) and b) there are any plans to add a capability to the BMV-712 to restart with the last known SoC.
Thanks in advance.
