Fortres Battery Stack SOC

Hello - Have two Fortress eVault Max in parallel. Its been manage by voltage since have not been able to use the schneider SOC logic. On the battery screens there is more that 14% difference on the SOC of each battery display (78.9% vrs 64.7).  Voltage reading is the same on each battery.  Question is this normal,  what would be the max differential in SOC on stack battery. 

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    I tried the Fortress website for manuals... And found some broken links and less than detailed information.

    From this quick start:

    https://www.fortresspower.com/wp-content/uploads/2021/11/quickstart-guide-REV1.pdf

    Are you meeting these numbers? Many BMS (battery management systems) seem to "reset" to 100% when charged to full voltage (54.4 volts in this case)... If the batteries operate at less than 100% full charge for day/weeks/etc., the BMS can drift apart over time (and cycling).

    I would suggest contacting your battery supplier or the factory support folks. Because this could involve warranty issues--You need the "official" engineers to work with you... It could be almost anything from "normal" to needing to upgrade BMS firmware. I would suggest that anything over ~10% difference between BMS capacity values should be investigated (just a guess--I have no experience).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset