I got to 42 in EV this weekend, about 300 miles after I crossed over 15,000 miles. I have a short grade near my house that I coast down and it is always a toss up if I will be in EV mode or ICE because I drive it right around 40 MPH. On Sunday morning I noticed I made it in EV mode witht the needle just above the 40 mark on the speedo. I was slightly shocked. I assumed it would never exceed the 38 MPG I usually can do, but this time it seems like I did. As soon as I touched the gas the ICE kicked in and away we went.

Temp was in the high 80s, cabin A/C was on recirc (not max) and the car was well warmed up.

Chris Brown

 

Good job Chris. I can usually get to 40 and above on demand. I think the more miles you have on the car the more interact it becomes. Of course, there are some times there is no way I can coax it into EV at any speed.


I think it is a matter of driving barefoot and training over time.

 

There is a hard limit to how fast the vehicle can move before the ICE has to be running. This is related to the redline for the motor generator. On the Prius I it was 42 mph. It's probably very similar in the FEH, if not identical.

 

Why should this be viewed as some kind of victory? Long before hybrids (and steering column locks & power brakes) you could turn your car off and coast down a hill using no gas. Whoopie.

I'm more annoyed that the gas engine *doesn't* turn off when I'm coasting down a hill. If the battery has plenty of power and the car is coasting down a hill, what is the point of the gas engine being on?

 

I can think of three scenarios that explain the need to run the ICE.

1. As has been mentioned before, at a certain speed the ICE has to spin to protect the motor generator from overspeeding. That speed appears to be approx. 42 mph.

2. (conjecture based on personal observation) At some point the motor generator will spin up the ICE to consume excess battery power. Since the computer works to prevent the battery from being over or under charged, if the charge level gets too high it has to have a way to consume some of that energy without increasing the vehicle speed. This appears to be what the engineers chose to do. You can see the energy flow arrows reflecting this at some point.

3. Because on downhill stretches the battery is accepting a charge at a higher rate than at other times, enough heat may be generated as to require the battery AC to be turned on. This only works when the ICE is spinning.

Note, in all these cases, while the ICE is spinning, it's consuming very little fuel. You can try the "L" mode on the gear selector and you will see that once the battery is charged the system will gladly spin the engine up to 4000 RPM to help brake your descent.

By the way, coasting downhill without the clutch and transmission engaged is illegal in many jurisdictions.

 

Hi Stevewa:
___Sorry for the OT jab but I wonder if you heard that 56 mph in a 55 mph zone is illegal as well although I have never heard of anyone being ticketed for that either. Have you …

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

Perhaps, but coasting downhill can be dangerous. For instance, what if your brakes fail and you're going to fast to re-engage the transmission?

 

I don't think you need the transmission in gear for the breaks, I think the engine just has to be running so it can fill the vacume canister.

If your breaks fail god gave us something called an emergency break. If that fails as well then your realy having a bad day and you were probably destined for an accident anyway

P.S. Don't take this post too seriously. It was my attempt at a bit of humor.

 

Hi Stevewa:___Many of the best coasts start with a downhill … When you are in a bumper to bumper jam on a long downhill slope, that downhill can save a tank let alone limit your emissions to 0 vs. everyone else ICE fired off around you

___Do you think anyone in a FAS would be running well above the speed limit down a steep enough hill or mountain at speeds higher then tranny re-engagement at the same time their std. and emergency brake(s) would fail? I know some hills I will FAS to upwards of 55 mph with a long flat or uphill afterwards for slowing to a crawl or stop but I will not FAS down a mountain. Higher then tranny engagement would be very high up in the speed range indeed. Where that is would be anyone’s guess? Probably the low 80’s in the Accord. The sticks … Any speed with a throttle blip to rev match would bring you right back into gear. I would not drive down any mountain upwards into the high 60’s without brakes and the ICE fired up.

___Finally, driving down a mountain or steep hill when your std. and emergency brakes as well as tranny fails can be dangerous no matter what you are driving or doing …

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

FYI -

There is not need to the ICE to run for streering and brakes. THey are both electrical. I'm sure with the tranny in an honest neutral the FEH couls coast far and above 42 MPH, but I don't think I would be trying that. It is a pretty heavy vehicle.