Folks:

Recently I've observed some somewhat odd behavior in my 2005 FEH ...

When I'm coming off the expresway, and I'm coasting down the exit ramp, the ICE will shut off (as I would expect it to) ... but as I apply the brakes to slow down, the ICE will turn on again, and then shut off about 20 seconds later after I stop.

The battery is fully charged, as the ICE had been running when I was at highway speeds.

Not sure if it's a problem, possibly related to the outside temp, or what.

Any thoughts?

david

 

Since the battery is fully charged, touching the brakes cannot cause the regenerative brakes to operate. Instead, the engine is turned with no/little fuel used in order to slow the car with the load from engine compression.

 

Same thing happens to my 05HCH. When the battery is fully charged and especially during colder weather, no regen occurs when I apply brakes. Only after the IMA is used for a few minutes will it begin to recharge the batt's again.

 

In that case, shouldn't it just use the brake pads?

david

 

Are you by any chance coming off the ramp in "L" as opposed to "D"? If you are using low it will want to stay in regen mode whereas in D it will lean more toward using the friction brakes.

In both of mine, when I decel in L the ICE will come on while in D it usually won't in the situation you descibed.

 

I don't understand all the details, but the regenerative brakes still go "on" even if the battery is full. But the electricity generated is not sent to the battery but instead to the generator which spins up the engine. You can sort of catch this in the navigation display.

So the brake pads aren't needed in this case unless you ask for a quicker stop than is possible from the (software-limited) engine/generator braking.

 

Nope.

 

What you described in your first post is not unusual.
Mine does it all the time.

While annoying, perhaps, this is normal.

-John

 

The reason for using the engine to brake is probably safety. If you just use the brake pads and its a long enough slope (more than an entrance ramp surely) you can heat up the brakes enough to damage them, warp the rotors, or worse yet as I've heard described on CarTalk, boil the brake fluid causing the brakes to fail completely.

All cars use the engine to slow down (or in our case the motor). In fact in manual transmissions you are taught to downshift when slowing down on a grade, NOT to just hold the clutch in and brake.

 

Not to nitpick too much, but the FEH is an HSD, not an IMA. Yes, I'm well aware of what you meant, I think we all are.

Anyway, yes, this has been discussed before. Two of the better threads (IMHO):

https://www.greenhybrid.com/discuss/...-off.4347.html

https://www.greenhybrid.com/discuss/...ging.4281.html

And yes, this is perfectly normal and healthy.