KiwiME
Well-Known Member
Checking it now at 12.82 V the BM2 says 100%. I don't know what the OBD2 data would say but I don't pay any attention to either of these percent evaluations because it's not clear how they work or if they are accurate. I think the battery voltage always being over 12.5 V is adequate to maintain long term life.
The problem with using OBD data in general is that the car must be in Run, Utility or Charging modes and that means the 12 V system is fully alive and will start charging the aux battery. The BM2 measures and logs voltage with minimal disturbance, just 2-4mA. The OBD might have a more sophisticated way of determining SoC but we don't know that, or if the PID is correctly formulated. I've seen low numbers as well that made no sense so I don't trust it.
The problem with using OBD data in general is that the car must be in Run, Utility or Charging modes and that means the 12 V system is fully alive and will start charging the aux battery. The BM2 measures and logs voltage with minimal disturbance, just 2-4mA. The OBD might have a more sophisticated way of determining SoC but we don't know that, or if the PID is correctly formulated. I've seen low numbers as well that made no sense so I don't trust it.