Hi Rev in Neutral gear

Hi Smoke...,

This is a technique used to pull the battery out of overcharged condition. The battery is used to pump the engine until its charge is at a lower level. Coming down the hill the regeneration charged up the battery too much. If you had continued on the electricty would have quickly been used pushing the car. But, if you get caught at a light, the battery will turn over the engine to run down the state of charge to an acceptable level.

I am not sure what is going on in the parking lot.

 

in neutral?

don't you mean DRIVE? or PARK?

Neutral is a whole different ball game, which prevents the engine from starting OR stopping.

 

Why are you using N?

As the first responder said, this is normal and is used to reduce the State Of Charge (SOC) of the traction battery. It sounds like the engine is racing, but all that is really happening is MG1 is spinning the engine as a big pump. The friction of pumping air through the engine uses up excess electricity. Usually you see this sort of behavior at the bottom of a big hill. The engine will race, stop, and race again. The cycle will continue until the SOC is back at an acceptable level.

Tom

 

I know what he's talking about, although it's not a particularly
high "rev". In early warmup stages the engine is run in that
ignition-retarded mode with a light electrical load placed on
it, open loop, and that only works in P or D. Going to N or
reversing out of somewhere lets go of this and the engine goes
back to as close as it can get to "normal idle", but the parameters
for that are all different and the closed-loop control isn't ready
to kick in yet. So the ECM takes various wild guesses as to
what it should do with mixture, throttle control, etc and the
resulting RPM can be quite different from the controlled warmup
run mode. If your throttle position sensor is very slightly
off, the RPM can shoot up to around 1400 briefly. All this
generally settles down once things get warmed up.
.
_H*

 

No, the SOC issue is only applicable with a very full battery - all green. If it happens at other times, hobbit probably has it figured out, unless, of course, something is failing in the control loop.

Tom

 

Ok, If I'm understanding this right, your issue is "high idling rpm - even in neutral"? correct? Because the engine NEVER turns off while in neutral.
If so, what rpm is it running in Neutral? How far into your commute does this happen? Are you in stage 4? Whats your coolant temp?

 

It sounds normal to me. I think you are misinterperating delayed idle shutdown in S2 or S3 at a stand still for high reving.

 

Tonight my ICE started racing in "P", after going down a hill then parking. The battery SOC was full green bars. It was revving at about 2500 RPM (per ScanGauge), which scared me, until I powered it off after about 10 seconds. Has anyone had theirs rev this high to discharge the battery? I have experienced the multiple starts/stops wating in traffic, but not this before.

 

Completely normal. The engine was not running, but simply being used as a drag to burn off excess charge. If the traction battery SOC gets too high, the control system will work hard to bring it back down. If the car is standing still, there aren't any good options for burning off charge, so the ECU commands the electric motor to spin the engine. Normally it does this in a series of bursts. It spins the engine , stops and checks the charge, spins the engine again, and repeats until the SOC is at an acceptable level.

Tom

 

Thanks, it must be the cold weather allowing the battery to become overcharged more easily. This will be my first winter with the Prius.