I have a BMV 712 monitoring my two 100 Ah LFP batteries wired in parallel in my RV for about 3 years now. Recently, I have noticed that the SOC will reset to 100% for no apparent reason. This month, I purposely fully charged the batteries, synced the BMV and then ran the batteries down to 90%. I disconnected all routes of charging (solar, alternator and shore) and watched it for several weeks. During that time, it stayed at 90% until one morning I checked it and it was at 100%. I have the unit programmed to “Keep SOC” on reset. I have tried swapping the shunt with another BMV and see the same confusing results. Any ideas would be appreciated.
Ypu might find the battery is randomly disconneting output and it is resetting to 100%
What absorption voltage do you charge at on your chargers and what is the “charged voltage” set to on the BMV.
I was kind of thinking it may be the built-in BMS on the lithium batteries, but am not quite sure how to confirm. I just upgraded to 4 new 100 Ah batteries. We’ll see if the problem persists.
If it is a Bluetooth capable BMS it may record the number of disconnects.
I have the charged voltage set to 14.2 and the AC-DC charger in the RV is set to 14.6.
Unfortunately, these are 9 year old batteries and do not have smart BMS, but the new ones do. What is curious is that this is a fairly recent phenomenon. Up until recently, the BMV worked as it should. I plan on putting it though some testing this weekend.
Those voltage settings look good so should not give synchronisation to 100% without proper charging occurring.
I have also had this problem. It seemed as if it had been powered off then back on, resetting itself. I replaced the wire from the battery to the shunt and that fix lasted for years. Now its acting up again. You might check the connections at both ends and also at the in line fuse.
Hope that helps
Check the battery settings in the bmv, at the bottom there is a field for reaction to disonnect, make sure its set to “keep SoC”.
And ofc not only the charged voltage should be set 0.2 under the absorption voltage of the chargers, the tailcurrent should also be very low, 1% , eventually even lower, otherwise a cloud can trigger you to 100% 
I have battleborn batteries. They have a video to set up your monitor and I have done that but I can find nothing about reaction to disconnect except #16 soc relay - set to 50. How do you change it to keep soc?
All in the Smartshunt…
I called battleborn and they feel that its because I do not have the bluetooth version . They say this is a very rare problem.
do you think that a newer monitor with the newer firmware would take care of this
It depends exactly on what model and firmware, I had a BMV 702 non Bluetooth version from 2020 that had the “keep SOC” choice with current firmware. Updating firmware would be my first thing to do if you have a route to do that. The SmartShunt and BMV 712 will have this option. The other option is to note the SOC down before turning off then you can manually update it.