Recently we went on trip requiring a 3 hour ferry ride. Decided to keep it in READY to listen to the stereo and maintain a minimal level of heat. I noticed the engine kicking on and no arrows from or to anywhere. The HV battery gauge was mostly down to 2-3 bars but still no arrows. There were times that it kicked on and the arrows showed the batteries being charged too. Was the engine kicking on without charging just to maintain the engine coolant temp to provide heat for the cabin, or what?
Yup. What you've described is completely normal. The Prius has to maintain clean emissions by keeping the catcon hot and it will also start up if you are calling for heat in the cabin, so the ICE can heat the coolant for you to have some toasty warm feet and hands As far as I know - Im relatively new to the hybrid game myself, its not unusual for the hybrid battery to get down to 3 or so bars in an extended readied mode like you describe on the 3-hour ferry ride. Remember, the Prius knows whats best for itself and wouldnt purposely kill itself - its designed to protect the traction battery as a top priority.
You said you left it in ready to provide heat. It runs the engine to provide this heat on and off as well as maintain certain battery levels, that is, it won't run it up to all the full bars though. Not a big deal.
Probably the cabin heat. It will normally only kick on to charge the HV battery from 2 to 3 bars and then switch off again. But it will also switch on and off to maintain coolant temperature and also for cabin heat too. Other than in the warm up stage in a morning it is unlikely the car ever charges the HV battery past 3 bars. Well it's a bit more complicated than that. If it's warming up the cabin it uses that opportunity to charge up as well. Believe me, if there's a problem the car lets you know!
Ok, thanks guys. I thought the cabin heat was the culprit but just wanted to make sure. I hadn't seen that before. So I'm thinking to provide cabin heat as needed in that circumstance the engine starts but then disconnects or does not engage MG1, that charges the HVB, to reduce the drag on the ICE that is only running to heat the coolant to provide the heating source for the heater, making for improved efficiency?
