High revving when battery full

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This is normal for the HV battery to bleed off additional charge when full. Are there any stretches of downhill before this happens?

You many want to balance or recondition the HV battery. How many miles are on the HV battery, and is it still the original?

FYI : you're moderated until you've posted 5 times.

 

A Prius can do that to shed energy. You're hearing the electric motor spinning the engine as a load. No fuel is being used. Even a healthy Prius can do this under the right conditions, so don't worry too much.

I don't know the exact formula or circumstances, but generally speaking it involves the state of charge being fairly high and the battery temperature quite warm.

The battery ECU has its own logic and thresholds and sometimes decides that the battery should be less full and less warm. Using some power to twirl the gas engine accomplishes both at the same time.

Then when you take off from the stop, you get to use that electricity for practical effect, moving the car- the ECUs figure this out and stop wasting the electricity.

 

How long has it been since you had the MAF Sensor and Throttle Body cleaned? Both can effect the engine idle when they are dirty.

Pro Tip: Disconnect the negative battery terminal before cleaning them and expect the computer to take 20 minutes or more to recompute/readjust everything when first running.

 

Don't do this, all you're doing is making the car less efficient. The car is quite capable of managing itself and will not allow the battery to overcharge or overheat,

 

I totally agree with this,

It can also be more dangerous and wear out your brakes sooner.

If you are going down a long hill use B mode on the shifter to induce engine braking. This will also let the battery charge up more slowly, which is better for the battery as far as I understand.

Also, read the owner's manual when you have time. You can't go wrong following the owner's manual's recommendations.

 

At that mileage a HV battery rebalance using a gridcharger/discharger would be a good idea.

Numerous other maintenance items as well. Have you ever changed the spark plugs, transaxle fluid, or cleaned the HV battery fan?

 

No. A Prius is much more gentle with its ATF. It does have the unusual element of exposing the electric motor coils to the ATF for cooling, so it is strongly recommended to stick with the real Toyota stuff, but there's no clutches or valve bodies or anything like that, so new fluid won't change perceived shift patterns or anything.

From the Prius driver's seat, you'd never know the ATF had been changed.

 

The ATF problems in other cars is due to hyrdaulic circuits that the Prius doesn't have.

A Prius transmission is a lot like a manual transmission. It's just some gears spinning in lube. No hydraulic circuits to gum up and plug nor high pressure against gaskets to burst.