I don't think the restarts are related to CAT temperature. Mine will stay off for long periods of time as long as I have a good charge in the HV battery and the outside temp isn't too high. Your restarts are probably a result of one of two things. Low battery charge or high battery temp.

Do you have the NAV with the battery display? There is a constant drain on the HV battery even if little else electrical is running. If the battery is low and the engine is off, every few minutes, the battery level will dip below the lower threshold and the computer will restart the engine to charge the battery SLIGHTLY. A few minutes later the battery will drop again and the cycle will repeat.

The other possibility is that the battery was getting too warm. The cooling system of the vehicle also cools the battery. If the battery gets too warm the computer will cycle the engine on to run the AC for the battery. When the battery reaches a good operating temp the engine shuts off....when the battery heats up again it will cycle on again.

 

Thanks for your suggestions Tim. The temperature was not too hot outside, and I had driven for some while before, so I thought the battery would have enough charge.

I don't have the nav unit, but I have a Scanguage II. I was reading that I can get the HV battery temperature that way. Perhaps I can try that if it happens again.

Duncan

 

This is normal operating procedure for the Blue Water Bridge. That bridge is the busiest US/Canada border crossing in the country. I keep my sailboat in a marina that you can see from the bridge (on the Canada side) and go there nearly every weekend -- at least every weekend when the weather cooperates.

It used to be -- even after 9/11, that the mid-day traffic on Sundays was bad, but by late afternoon the backup would reduce to maybe a 30-min wait or less. This year, even very late, the traffic is backed up for miles down the 402 waiting to re-enter the U.S. in an hours-long wait... which is why it's a good idea to be in the Nexus program (but that lane closes at 7pm).

The delay is US Customs & Immigration. The deal about the Canadians not taking the toll to let people onto the bridge is because the backup is soooo long that they don't want the bridge to be completely packed with cars. There are 3 lanes returning to the US. The left-most lane is for commercial trucks only. The center lane is for Nexus and Fast-Express members only (if you see cars whizzing past you in the center lane with their hazzard lights flashing, they are Nexus cars). The right-most lane is for "everybody else". It tends to be backed up about 2/3rds of the way across the bridge. After the line ON the bridge shortens enough, they start letting people on it again for a while until it stacks back up. Wash, rinse, repeat.

The good news is it's usually about 10 degrees cooler near the lake and up on that bridge. So I usually just shut off the AC, roll down the windows, and let the car do what it wants w.r.t. the engine cycling. If it looks like the traffic isn't moving I'll shut it off.

Regards,
Tim

 

That never even crossed my mind! They should just let cars trickle through then, rather than flood the bridge and then stop everyone for long durations. Although, maybe they do it this way so that the regular bridge-crossers who know what the delay is for can shut off their conventional autos to save gas...

 

Everyone has had good suggestions so far, and everyone has contributed to little pieces of the puzzle. From 2.5 years of FEH experience, and reading every technical document possible, here is a summary, in order:

#1 reason for engine restart is catalyst too cold ( very common )
#2 reason for engine restart is engine too cold (winter, or short trips anytime)
#3 reason (almost tied with #2 ) is HV battery charge too low
#4 reason ( very infrequent ) is HV battery too hot.

Now, driving habits, and conditions may reverse the frequency of #2 and #3, but #1 is almost always the reason, and #4 is least often the reason.

A discouraging fact is, even if you added a much larger battery pack, extended EV driving will not be possible without extensive computer reprogramming, since the conditions of catalyst temperature and engine temperature must always be met BEFORE EV driving becomes possible.
( and must be maintained during EV driving )
-John

 

Thank you for your comments John.
I think it was mostly #1 in my case.

Duncan

 

 

Update - I crossed the border again today.
I set one gauge on the SC-II to show oCWT, which I think is the coolant temperature.
When waiting in line, and the temperature dropped below 60 C, it started ICE, and when it got over about 72 C it turned off ICE. It was quite consistent.

Duncan

 

That is different than my 2005!

With total consistency, mine shuts OFF at 60'C ( 140'F )
and will restart every time at 52'C ( 125'F ).

Interesting!
-John