Does the Prius have an engine brake?

I never liked the B mode compared to alternatives. But yes, please use if when coming down off of mountain passes.

I just got home from a snowy mountain pass. I love the Camry/Avalon shifter with 6 pseudo speeds called S mode with + and - symbols. This gives me a lot more control over how much "engine" braking I have in my 2013 Avalon hybrid, like today when I was trying to maintain a rather constant 25 mph without riding my brakes. This was the main reason we got the Avalon instead of a Prius v that had basically the same mileage for the same price, because the V had only a B mode.

I also would use the B mode or S modes from the top of a mountain pass because the battery will fill up by the time one reaches the bottom anyway, at least in the non-plug-in hybrids.

 

First part, yes......
2nd part, it DOES charge the battery.

For just driving around town and of course highway driving, it not practical, and a little dangerous.
When you let off the throttle pedal, then will slow down much quicker. Because it's for Braking.

EVERYTIME I use it to slow down, yes, in the city, the charging amperage goes up.

 

Right, because the B setting has two effects:

1. it is programmed to apply a higher amount of overall car slowing than in D when the go pedal is released. To slow the car at the same rate in D, you'd have to use the brake pedal a bit (or have cruise set for below the current speed).
2. in the HEV, it is programmed to achieve that car slowing by a more engine-heavy/battery-light balance of slowing techniques. That can still be more charging amperage than you would see with the same control inputs (go pedal released, less actual slowing) in D. It'll be less charging amperage than you'd see with the same rate of slowing (using a bit of brake pedal, or cruise) in D.

Because the PHEV has a much larger battery, rule 2 is relaxed for the PHEV, where the owners' manual actually touts the regeneration boost in B mode.

In the HEV, don't forget that the balance of engine braking and regen gets tapered towards lower charging current and more engine braking the closer the battery is to full charge. In the NiMH HEVs, by 80% SoC you won't be seeing charging amps at all, whether in D or B. The taper is just earlier and steeper in B.

 

Same setup on my Venza. S-Mode for the win!

 

OP's AI summary seems pretty spot-on, likely from various sources, including Priuschat. Toyota really needs to flesh out the paltry explanation in the Owner's Manual.

 

Yes, like I said, use B mode.

What bothers me is I've been in 2 and 3 speed cars before. My first car was a 3-speed 1951 Plymouth Cranbrook. But those cars are ancient compared to modern cars, yet that Plymouth had more gear options than a Prius.

But now that we live in a day and age where cars have not only 10 or so gears, or CVTs with virtually any gear, we don't have any more control than a single B mode.

I guess this just bothers me from driving 18 speed trucks. Going from 18 choices down to two (D and B) seems like a major downgrade, no pun intended.

 

I wonder how it works in an ev with full battery

 

The switch to engine braking will happen automatically when the battery is full without using B.

Using the brake in Drive will modulate the rate of regen braking and will initiate engine braking when necessary. No need for B to achieve this even on a long downhill near Gunnison Colorado.

It is easy to hear the transition to engine braking. The engine is not actually running on gasoline but is rotating.

Obviously if you don't use the brake to regulate your downhill speed the car will gain speed.

 

Yeah, I probably am over-thinking this. But I still love the control of more than just B.

Lots of modern cars will also automatically engine brake. I'm not sure if the Prius does that, although regen braking is basically the same thing.

Another option is to leave the cruise control on. If not too steep and your car isn't too full the regen, then engine braking, will just hold you to one speed. Sometimes it's not enough and you have to use the service brakes, which then, of course, kills the cruise control making one have to turn it back on again.

I use S-mode (B-mode) because it does charge the battery more slowly, which should, in theory, extend it's life, especially when you drive over a mountain pass and back at least once, if not two or three times a week.

I guess I've also gotten lazy with using my feet as much, which is weird because I love manual transmissions. But when using the accelerator or brake to hold a certain speed, it's so easy to get going much faster or slower than the goal. Cruise control helps when accelerating. Different gears help kind of maintain a certain speed, albeit a small correction ever once in a while will still be necessary. Full control of speed via the foot means I have to be glued more to my speedometer.

 

B-mode is used to save your brakes; so you can still stop when you get to the bottom........ I learned this very young, with too many people in my car and a stop sign at the bottom of a long steep hill. I was lucky there wasn't cross traffic; because the stop sign faced me at the bottom of that intersection. I blew through that intersection at around 15mph - standing on my brake pedal...... When I was able to stop; the hubs was glowing red hot. So I always use Lo or B gear on long steep descents.

 

Not sure what to speculate may have been going on with Paul's gen 3, but any current driver of a gen 3—there are plenty of us—can readily confirm that isn't the normal behavior.

Exactly, and easily confirmed.

In my gen 3, it isn't an abrupt switch, but a tapering toward more engine braking and less regen, beginning slightly above 70% SoC, and complete by 80%. In B mode, the taper is steeper and starts earlier.

 

uh-oh

 

oh sorry, I was just commenting on the baseball game. sox are up 4-zip

 

yeah....if only Toyota had actually thought about setting the car up with a way to slow down or stop when going downhill. Maybe they'll do better next time...

 

Were you aware that you can control the level of engine "braking" while in "B" mode with judicious application of the brake pedal and accelerator? It's not clear what your 3-speed Cranbrook could do on steep descents that a regular Prius can't do as well or better, including adjusting the ratio of wheel speed to engine speed when needed.
What 2-speed cars were you referring to? Powerglide automatics, or a Model T?