Today I was at the field and I decided to try the suspect charger two ways, one with the engine off running directly from the auto battery and once with the engine running. I did disconnect the charger when starting the engine.
Same results, works fine with the car engine off but over charges the lipo's beyond 4.19 or 4.20 with the engine running. The lipo got up to 4.35 before I shut it down. I did manually check the setting and they were OK. Same setting for both attempts.
So I'm going to try to contact Hyperion and see what they say. There was nothing in the instructions about not running your auto engine.
It is really no big deal but now I'm just want to know why it is doing this.