How can I stop this?

Ok back on this topic again.. Strange thing happened to me today. Temp was in 20's so pretty cold.. both driving out in the morning and coming home at night ICE fired up while I was CLIMBING a hill on the highway.. had about 80% charge in the morning and about 30% in the evening.
It's a hill I go through everyday, and never had any issue going up on EV so I could not come up with a reason why ICE fired out today... anyone?

 

The combination of low temperature and high power demand probably triggered the ICE to come on. If you had the climate control on, 20F is very close to the lower limit of 14F the heat pump can operate. The car determined that you needed more heat or power or both from ICE.

As you can read in the manual, there is a catch all declaimer from Toyota stating that Gasoline engine may operate in EV/EV auto mode:

"When the system determines that the gasoline engine needs to be started."
Also, there are other instances when ICE comes on in circumstances not described in the manual as pointed out in the manual. We don't know all of possible occurrences.

 

Thanks for the info. Obviously I never did go through the manual..
It actually says there under 3rd bullet point, "When driven on a hill"..

What I find kinda funny is 3rd and 4th bullet points: When hybrid system temp is high, and when hybrid system temp is low. So it has to be totally perfect for EV to function. LOL