I believe the FEH computers run a battery conditioning program from time to time that requires the ICE run for a fixed period of time. I would not worry about it or try to bypass it, just trust the computers and let them do thier thing.

Simplying having the ICE running won't make a huge differance in your fuel economy, the engine consumes very little fuel at low RPMs and 5 minutes of idleing won;t make a big differance. Running at high RPMs even for a minute or two will however have a big impact on economy.

Chris Brown