My BM2 on order still hasn't shipped (from China) so I plugged in this volt monitor (has a couple extra USB ports, too). On start up, the voltage briefly goes up to 14.3V indicating a bulk charge. Shortly afterwards it goes down to 13.5 indicating a float charge, which is what you would expect with a fully charged battery. But when driving it drops to 12.7V which is still 100% SOC, and then occasionally goes back up to 13.5 and then back to 12.7. I actually would have expected it to stay at 13.5.
When I shut down the car and before I open the door (12V port is still active), I see the voltage drop pretty rapidly, down to 12.3 and going even lower before I open the door. Not sure what it is doing, but seems to have a heavy draw for a while when shutting down. When I check the battery later with a multi meter, it is stabilized at 12.3 or 12.4, which is not bad, but certainly not at full SOC. Not sure what to make of that. Perhaps while my battery checked out OK at the dealer, it has indeed lost some capacity as indicated by the SOC after the surface charge was removed so rapidly.
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Where did you get this plugin volt meter?
