The point of contact is still the tires, but the slowing friction (compression) occurs in the engine instead of the wheel area so there is no chance of locking up and entering a skid.

From my observation, this function has less in common with the old "Low Gear" setting and more in common with a "Jake Brake" on a tractor-trailer.

 

Exactly! good explanation. folks in the cold country try this you will like it, feels like you have more control over the car on ice and snow. I have yet to get the car into a skid this way.

 

I think the ground-tire contact point is blind to what happens upstream of the drivetrain.

If engine braking is less likely to lock up and skid it's only because it doesn't decelerate the car as much as braking. If you braked gently and slowed at exactly the same m/s^2, it would be no different.

Compare:

1) spinning up a massive flywheel to decelerate
2) releasing a parachute
3) having a vehicle in front with no space between the cars do the braking

 

The only time I've seen the last bar on the battery charge display turn green was using B mode on a long grade. IIRC It was also showing regeneration at the time. I'll be going down a stretch Thursday morning that should let me check what does what when.

 

1) The braking force is transmitted to the road by YOUR tires which could lock up

2) No braking force is transmitted by the tires. The vehicle is slowed down by air resistance.

3) The tires of the OTHER vehicle transmit the braking force and could lock up. YOUR tires won't lock up.

 

Compare those to decelerating using B mode. Keep the rate of deceleration the same for each. This is just hypothetical and don't take into consideration slowing with B mode doesn't have ABS if the tires start to skid and that B mode only engages the front wheels and could result in yaw.

I don't think B mode is any different than #1 which isn't any different than braking.

 

I believe I was mistaken.

 

Exactly. That was also my experience last summer in the White Mountains. B mode all the way down - battery charged right to last bar.

 

Thanks to all who have responded to my query with their suggestions and info. I find the energy regeneration rather complicated, and you have helped to clarify it. Regarding the "Brake" transmission mode, my brother-in-law, who is a truck driver, was driving my car this week, and he enjoyed the B mode, saying it was like a J-brake. Is there any chance he was using it too much?

 

No, I doubt using the Brake mode would hurt anything. While the car is rolling. If you switch to brake when the engine is off, it will start the engine. I understand that the B mode is like a pre-set brake. If the car goes fast enough the generator switches to the engine for the braking or gearing down. I would think above 40 or 45 miles per hour. In other words the generator can spin just so high. Any faster on gearing down it then switches to the engine.

If the battery show max or a 100% charge then it will simply use the engine for any gearing down in the brake position.

A Toyota tech had earlier told me that was another reason they like to keep the battery charged at 80%. That leaves extra room for the generator braking. Using the brake peddle or the brake selection.

The main reason for the 40% to 80% charge was to extend the life of the nickel-hydride batteries.

This tech also told me there is a early prius around town with 225,000 + miles on it. The battery has never been touched. That gave me a secure feeling.

I wish someday that Toyota would make a hybrid where we can run in the EV mode at 50 miles per hour.