What will happen to HV batttery when you keep prii in neutral?

Never use N.

Why ruin your car? There is almost never a good time to use N. (If you find you never use the friction brakes, you could stop once a month in N, just to clean the rotors)

N is never the best MPG, N is never the safest way to drive, I am told there are car washes to avoid that need N.

Toyota is required by law to have N, you are never required to use it.

 

Sadly, it can not order a new driver.

Do not put your Prius in N use P.

 

Did you read the stories of people in car washes?

 

The HV battery will eventually stop discharging and throw a couple of warning lights and DTC codes. If the car is turned off, it may require a jump start to get it going again and you MAY have caused permanent damage to the HV and/or to the 12V battery. The car will do its best to protect itself, but there's just no way to overcome the driver from forcing a condition where the state of charge is reduced to a dangerous level.

Use N sparingly, if stopped use P if you need to keep rolling (such as a car wash) use N and watch the SOC meter, if it gets low, shift to D and use the brakes to maintain forward movement.

 

I think @DonDNH 's first sentence sums it up. Isn't this what killed a few Prius batteries, in pull-through car wash?

The only time I use Neutral is to roll the tires againt a curb when parallel parking on hills with curbs: more control than if the car is in Drive.

 

Yes. The gas engine runs.
If the system is OFF at the time nothing will happen; IE the battery won't discharge in the first place.

Edit: Maybe I missed something here.
If the "system" is ON in normal driving mode but in Neutral with car not moving (much or at all), will the design REALLY deplete the HV battery and not start the ICE to charge it ??
I don't think my C will do that......but now I'm not sure. A test is in order, I guess.

 

The gas engine cannot start up in N, nor can it shut down in N. Do not run down your HV Battery foolishly.

 

Why ??
I understand why it maybe can't be coupled to anything preventing it from starting.....but why not shut down ?
As a matter of policy maybe but CAN'T ???

I tested my C today and sure enough, it just sat there in N with the ICE running and doing exactly NOTHING.......until alarm messages and bells went off.

 

The prius uses M/G1 to start and stop the engine. In N, neither M/G has power.

 

By my understanding, the N gear effectively uncouples the HV battery by breaking the connection to MG1/MG2. Therefore, there is no drive to the wheels.

If the ICE is on when N is engaged, it will not 'auto shut off'. If ICE is off then N is engaged, it will not 'auto-start' because the 'demand' for these is from the HV.

By my understanding, the HV battery is isolated in N and it is the 12V battery that then takes on the burden of lights, audio, A/C, heated seats, etc. The risk to the car is therefore on the 12V battery and depends on the number of appliances switched on and the time spent in N. After shifting back to P or D, the 12V is recharged from the HV battery over time.

Please let me know if my understanding about this is incorrect as I do not consider myself an expert, just an interested amateur!

 

I still don't understand the STOP part.
Why is anything required to stop it other than cutting the power to the ignition and the fuel pump ???

 

How exactly did you come to that understanding ??

I see no reason to do that.

I think that N should be changed to "Tow/Maint" because it doesn't look like it is intended to be used in any normal driving situation.......except maybe where everything goes dead and you have to get it out of trafffic.

 

Well, Gen2 Prius computer logic allowed HV batt to discharge completely, for example, upon empty gasoline tank, and this explains a certain number of Gen2 HV batt failures. My undertsanding is Gen3 the computer logic prevents the complete HV batt discharge, but not sure about the N case.

 

The only reason or time I ever used "N" was when going through a drive-thru car wash.
Which I found to be VERY possible.
You just have to enter the car wash with a good HV battery level of charge. So the vehicle can make it through the car wash before the charge drops too low.
In 3 years, going through nearly countless car wash, I think I only got a warning message once. And it was my own fault. It was a hot day, and I sat in line too long with the air conditioner blasting.
In my opinion, if you have a good HV battery, at a good state of charge, neutral CAN be used to go through a car wash.
If it makes you nervous, or you have an older battery that discharges fast? Then don't do it.

That singularly was the only time I used Neutral.

I believe Toyota recommends putting The Prius in Neutral if "Emergency Towing".

 

The Prius is the first vehicle I've ever had, that can't be in Neutral when off. Maybe Toyota could accomplish that?

 

I am not sure either, if you want speculation, using MG/1 keeps the computer in charge of all three RPMs (engine, M/G1, and M/G2) where just letting the engine die as it feels like would have uncontrolled engine RPMs. But that is just speculation, I feel like I know way more about what the Prius does than I know why it does what it does.

 

US NTSHA regulations are clear it must exist and it must be labelled Neutral. 49 CFR 571.102 - Standard No. 102; Transmission shift position sequence, starter interlock, and transmission braking effect. | US Law | LII / Legal Information Institute