Gas engine turns on when coasting on battery full?

  • Thread starter Thread starter Costa
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Costa

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Not a concern but sharing an unscientific observation.

Perhaps it’s coincidence but I’ve noticed twice that when I charge the car to 100% and then I coast down a steepish hill the gas engine turns on. I have to charge at public sites so my clarity is rarely fully charged. I read in the manual that the clarity can’t do regen breaking if battery is full.


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I have experienced the same thing! While I think I understand most of when the ICE comes on, there are few mysteries and this is one of them.


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Costa said:
I read in the manual that the clarity can’t do regen breaking if battery is full.
Click to expand...
Right. When I leave home with a full charge I hit a stop sign in about a block. The brakes at that point need a lot more pressure to stop the car. After that, everything works normally.
 
The Prius (conventional, hybrid) has a mode when the battery is fully charged and can't regen in which it will back drive the engine with an electric motor in order to scrub off energy when you're applying the brakes.
This is also done if its selector is shifted to "B".

I doubt that that is what's happening with your cars, but it's possible.
 
css28 said:
The Prius (conventional, hybrid) has a mode when the battery is fully charged and can't regen in which it will back drive the engine with an electric motor in order to scrub off energy when you're applying the brakes.
This is also done if its selector is shifted to "B".

I doubt that that is what's happening with your cars, but it's possible.
Click to expand...

Prius PHEV did the same thing. It's likely this is what's happening.
 
This has been driving me crazy! For me, it's also on a full charge, and it's also braking downhill for a stop sign just a block from my house. I've been trying to see just how far I can stretch my odometer before my first stop at a gas station, and this has occurred three times this past week. And once the ICE kicks on, it remains on for almost 10 minutes before it will switch back to all EV mode again.
 
Maybe try doing a 10 minute precondition to pull the charge state down before you start off on your drive.
Let us know if this helps.
 
Sounds like it is going into a mode for engine braking.

I suspect this is why the HV charge mode doesn't go past 60%. If you're descending a mountain you could max out the battery.
 
css28 said:
Maybe try doing a 10 minute precondition to pull the charge state down before you start off on your drive.
Let us know if this helps.
Click to expand...
That's a good idea! Or maybe I'll just do a short burnout down the street when I leave in the morning to drain a bit of juice. ;)
 
Any mode? Does it do this in Econ? I agree that it sounds like it is starting the engine to provide some sort of braking function to the traction motor, I think the Volt can do that without starting the engine, but maybe the Clarity can't.

I know you shouldn't, but you could try N if it won't make you coast too fast. Not sure how long/steep this hill is. Maybe combine N and brakes, not sure if that would behave differently. The manual will tell you to avoid N as coasting in that gear means you can't control the car's acceleration.
 
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