This morning my '06 FEH did something I haven't seen before in either this or the '05 EH.

The car was warm as I had been running around between work locations and I had been in and out of EV mode like normal. While coming down a pretty good hill, decelerating through 30-20 mph, instead of the ICE shutting down as I expected, it revved to about 3000-3500 RPM and held there for about 5-8 seconds while I stopped at a red light. After a few seconds, it returned to a "normal" idle like it does when charging the batteries.

Like I said, the car was at normal operating temp, I wasn't using the a/c at all and the car was otherwise acting normally. I have a total of about 8k miles on the two and have never seen either do anything like this.

Any ideas? Anyone ever seen this before. Thanks

The Prius II exhibits similar behaviour when regenerating down a long hill. From what i understand, when the battery is in danger of becoming overcharged, the ICE will rev so that the MG can have something to work against in order to drain the excess charge. It has happened to me several times.

Was your battery full when this happened?

It's a Wonderful Day for Science!

Mine has done this before... going down very steep hills. I think it's something to do with the ICE revving up to assist the "engine braking" - either to assist the electric motor or take load off of it. I've heard of others experiencing the same; I think it's normal.

Thanks Dan and Randy,


I feel a lot better now. I'm never sure as to the state of charge in the batteries since I don't have the Nav/Audiophile system. The little dash gauge always says "available electric power normal" or some such thing. I have never seen it read other than normal. I would imagine that my batteries were pretty well charged as I was toward the bottom of a pretty good grade and was running in L to keep off the friction brakes.

I guess maybe I remember reading about the engine running to discharge the battery some - seems kinda counterintuitive but whatever it takes I guess.

Thanks for the quick replies.

Ray

Likewise mine had done this when decelerating quickly on an interstate off ramp. The only trick I have found is to let you foot off the brakes and coast(if you can)--rather than braking. In my case, on the way to work I brake to 30mph on the ramp and then let off and coast for 5-10sec--rather than continuing to brake. This keeps the ICE from doing what you described. If I continue braking...the ICE will shutoff, then suddenly come to life.

Of course in some situations where you have to stop(stoplight,curve) this trick won't work.

This is normal. Don't worry.

Nate