Long shot... If you happen to have a
lithium battery, the tao bms has a Monitor with a CAN interface compatible with RV-C, NMEA, SMA and more standards. CAN messages can be defined to suit proprietary formats with voltage,
current, temperature, SOC, SOH and other data. It also does data display/logging with a browser interface...
Unfortunately that would not
work if you have lead acid
batteries or would be expensive if you do not need a BMS.