Over charge in mountain road

Yes


iPhone ?

 

once the battery is full, the engine runs without gas to help slow down the car and burn off excess electricity. i think what you're hearing is normal.

 

I've had a fun 6 mile mountain run once. On the descend half, the battery fully charged and I wasnt able to use Regen. When braking, friction brakes are used. I don't recall the engine kicking on though. What I did notice was a louder whirling Prius sound. I think this is because I had windows down and the Save-the-blind sounds were echoing off the mountain walls.

18 mpg on the ascend. About 36 mpg after the descend!

 

Is normal.

 

Long downhill runs, say a kilometer or more, are THE time to shift to B. It'll reduce the charging rate and use engine braking. I would think it also helps to keep you speed down a bit.

Ultimately: try to avoid mountains, as much as possible. Both the climb and descent are hard on the car. If you can find an alternate route, even if it's longer, that's preferable in my opinion.

 

You only need select B mode when descending the mountain and your HV battery is indicating full. You can still drive as normal, but you will not have regenerative braking from the brake pedal, only normal friction braking. I don't know how hot your climate is, but modern friction brakes should manage without fading off from heat. The whining noise you hear is the noise of both the electric motor and the engine spinning at the same time. It is nothing to worry about.

I hope that helps and you enjoy many happy miles in your Prius.

 

I would try to be preemptive: switch to B at the top of the hill, if you know it's going to be a long one. And, switching to B does not completely lock-out regen braking, especially if you still have room to charge. It will reduce it though.

 

That's right, but once the battery's fully charged on the Gen 4 in B mode, it is negligible.

 

You say that like it somehow matters ... yes, once the battery is fully charged, the car is not going to put more charge in it, whether you are in B or D. It will divert electrical energy to the engine, and use friction braking when you apply the brakes. Those are the only things it can do at that point.

The benefit of B mode at the top of a long downhill is that it reduces the battery charging rate somewhat, by proactively diverting some to the engine earlier than it would in D. If you know the descent is long enough that the battery will hit full charge by the end anyway, doing it in B is better for the battery, and delays hitting that full-charge point to further on down the hill, keeping more options open for the car to control. In D, you'll both heat the battery more, and reach the full-charge point closer to the top, so the car has no headroom left most of the way down, and can only use friction and engine spin.

And no, there is absolutely no reason to worry about the engine sound when it is being used to dissipate energy. There is a computer in full control of the process and it will not overrev or damage the engine. On a steep enough descent, you'll reach the point where the computer just won't use the engine any harder, and you'll have to brake to hold your speed.

Letting worry about the engine noise scare you into shifting away from B in those circumstances only defeats a useful design feature of the car.

-Chap

 

I think your answer suggests you totally misunderstood me. I was simply trying to explain to a man in Iran what was happening and hoping to allay his fears. May I draw your attention back to post #1 and #7? Incidentally, I am well aware of how my Gen 4 behaves in B and D when fully charged, but thanks for your advice anyway.

 

Cool solarized avatar, btw. The inversion can be interesting too. One I did manually, many years ago:

 

Isn't that a 'negative' display?

 

Not quite. What I did:

1. Expose print and commence tray development normally.
2. Turn on normal incandescent light for a few seconds, when the print is about half developed.
3. Continue development to completion, stop, fix and rinse.

At this point you have a mostly dark print, due to the extra light exposure during development, with the distinctive "solarization" edges. Then:

4. Sandwich the print (can be still wet) emulsion face to emulsion face, with a fresh sheet of print paper, with the new paper at the bottom, under the enlarger.
5. Expose to plain light, to basically do a print-to-print.
6. Develop that new sheet.

The solarizing process leaves you with a partially reversed, and very dark image, at the end of step 3. At the end of step 6 you've done yet another reversal of tones, the negative become positive, and vice versa. However now the print is predominantly light.

You can continue the process for multiple itterations, ie: instead of just developing the new sheet in step #6, you repeat step #2, creating another layer of solarization. This can be repeated more and more times, with interesting results. In my eperience it got more and more intricate, and then at some point, just went muddy.

Here's one further along:



And a crop from the full size scan of the above:

 

That image is somehow giving me anxiety. I might have some kind of phobia to those edges.

 

Each line, layer, represents one generation. That's close to 10 generations in. You get some cool gradations, in the back ground, lighter-to-dark tone., maybe 'cause the light source causing the solarizing was off behind the tray, on an angle. Again, next gen, it just went to doodoo, hard to explain.

 

Yeah, that's what I was thinking. I'm there too.

The little girl in that picture now has kids of her own, almost going into high school.

Sorry for the thread hijack, btw.