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

This is not the case, both charging the 12 volt system and the A/C compressor continue to work even in N. Both need 201v DC from the big battery, so it is not completely isolated. I suspect the M/Gs are electrically isolated.

 

I confess my experience with it was in a Gen 2, it would be wonderful if this was solved in more recent Prius.

(I would be wrong above, but I can live with being wrong if the car works better!)

 

I'm sorry for most if this exchange.

It finally sank in with me that you mean "the car is designed so that the user can't stop the engine when it is in Neutral" rather than "it is impossible to make the engine stop when the car is in neutral".

 

Much of the Prius tech is mechanically simple yet mysterious due to closed source software. We all question why the choices Toyota made were made. I find some self respect just understanding that they did make choices, that it doesn't "have" to be that way.

I hope you also find joy in understanding that someone thought 'This is the best way' and I hope someday you help discover why he (or she) thought that. With succeeding generations, Toyota refines their work.

 

The only practical use for N is when you are in a car wash where the car wash pulls you through. The time your car is in N won't be long enough to pose a problem.

That said, in N, your HV battery is being drained according to the load being placed on it (might be nothing, might be a lot). If your heater is running, your engine may kick in to keep the coolant temp up, but I don't know if any of that energy goes into the battery. The the time frame of a car wash, you have little to nothing to worry about. Otherwise, don't use N. It circumvents the Prius' programming to start the engine to charge the HV battery when it gets low.

 

could someone offer a detailed/technical explanation why no charging in N. nothing i read above explained that.
sorry if i missed it.

 

I can try.
Toyota designed a drivetrain that has no clutch, never shifts gears, and has just one gear ratio. It is mechanically very simple and efficient.

However.

U.S. regulations (and I am sure those of other nations) require automatics to have a gear with more braking than D, they are required to have an N, (oddly P is actually optional in the U.S. but I am sure it is required somewhere) and most of the order the gear need to be is mandated. P needs to be on the end, next to R, N must be between R and D, and the gears need to read clockwise. (On a Prius this is down, if they were horizotional it would be P R N D. The name and position of the low gear is left to the carmaker, Toyota chose B, as they do not actually use lower gearing)

If you want you can pick all that out of this law 49 CFR 571.102 - Standard No. 102; Transmission shift position sequence, starter interlock, and transmission braking effect. | US Law | LII / Legal Information Institute

So you have a one speed always engaged transmission and you have to meet US Law.

D is how Toyota designed it. Regulators made them add a small amount of engine braking to act like other cars.

R is just revolving Motor/Generator2 backwards. As an electric motor, it has no preferred direction of spin. The engine never powers the car in reveres and if it is running, M/G2 has to overcome its power to force you backwards, as engines only run one direction.

P is actually easy, Toyota forces a pin into the gears while you are in D. the pin prevented the wheels from moving.

B just adds much more engine braking to D. In B you will hear the engine get louder and busier the harder you press on the brake.

Now N is a challenge. Toyota could have added a clutch to mechanically isolate the engine, but they choose to electrically isolate it. By de-powering both M/Gs the engine has nothing to push against. M/G2 will not transfer power to the wheels because M/G1 can spin freely. If MG/1 was producing electricity, that resistance to motion would give the engine some ability to push on M/G2, and thus the wheels. Only by free wheeling M/G1 is the engine prevented from pushing the car. (Not powering M/G2 is vital as M/G2 is directly connected to the wheels)
With neither Motor/Generator acting as a Motor or a Generator, we can't produce electricity, all we wanted to do is not produce motion.

This odd behavior of N causes owners a fair amount of confusion. B is almost invariably mis-described in the automotive press, adding to owner confusion.

If you want visual aides while thinking of this, I like this video :

(Sadly he never demonstrates N which is just spinning the engine while neither M/G resists)

 

And yet the C still has on light for the back seat....and some models still have that infernal beep inside the cabin in reverse, but only SOME models.

Some things just don't have a good explanation.

 

US regulators wanted the Prius to CLUNK when you put it in reverse. (nothing ever shifts, so there is nothing to clunk) Toyota offered to make it beep instead. Toyota made the Gen 2 so that you could set it to one beep with no tools, so the Gen3 requires more work. Sigh.

 

But something about that doesn't make any sense either:
Why does my C not have that option ?
Why does that "regulators want" not apply to other models too......like Camray or Corrola......or hybrids of other brands ???

 

Your C stays in R all the time you are in Reverse, in other Prius the shifter goes back to the middle, you can't look at it and know you are in R. (The Camry also stays in R, although I could not find a stock photo with it in R)

Prius c


Prius


Camry Hybrid


In the NHSTA's mind you don't need a clue, you can see you are in R, but Prius liftback , PHV and v owners can't, so they get constant beeping. (I have no idea why the R in the instrument panel was not enough)

 

OK.....I always did think that kind of a "shifter" was stupid.
This just reinforces that impression.
Thanks for the information.