The [B] gear??

After so many years now, any salesperson that makes up an answer when you ask them about Prius is a clear warning sign. If they don't know, they should either admit it or *finally* look it up.

has absolutely nothing to do with charging.

It's purpose is to provide engine-braking, a benefit to your brakes when driving down a steep decline.

 

forces the engine to remain active (even though no fuel is being consumed).

Normally, it would stop entirely. But when you shift into , it keeps pumping the pistons. That causes some deceleration even without having to step on the brake-pedal. (By the way, the effect is so smooth, you'll find it helpful on ice.) This additional force helps to reduce the load on the brake shoes & pads.

Using all the time will cause lower MPG, since charging opportunities without using the brake-pedal are reduced.

 

I would NOT recommend B mode on ice.

In the first place, its decellerating effect is applied only to the front wheels, which is a destablilzing force.

In the second place, if engine braking should cause a wheel to slip, it won't be under the control of the ABS system. In fact, if wheel slip is detected, the car will respond by cutting off ALL regenerative braking instantly, giving the effect of the car lunging forward. This is done to ensure that the ABS can work properly, but it also has the effect of momentarily upsetting the equilibrium and leaving you in an off-balance condition.

The best course of action on ice is not to brake at all unless absolutely necessary, and then to use the foot brake (which has ABS) as gingerly as possible until you can get down to a safe speed. I'm not sure what a "safe" speed on ice is, because it would depend on the conditions, but it would not be much above a walk.

 

Re: Regeneration

Hello John: Your doing a great job! you and the other moderators as well. My question is on a comment you made awhile back: "Lightly touching the brake pedal will improve regeneration", upon releasing the accelerator regen automatically occurs anyway, why should it be more with the brake pedal pressed (lightly or not) Can you offer any proof of this? and what sort of feedback might show the Prius driver that INCREASED regeneration was occuring? I tend to do this anyway as I want the driver behind me to know that I'm slowing. Your comment on freewheeling was excellent, I have put that to use. ty Andy.

 

Recovery from an unexpected slip on ice works great. You just drop the Prius into the moment you discover you are going too fast for the curve.

It works great. I've tried it many times. Real-World driving has demonstrated that the engine-braking will not cause the wheels to slip.

In other words, when you detect that braking is too high of a risk, try .

 

While you are driving, electricity is generated using the 10Kw motor. The source of the power for that doesn't matter, either the engine or simply slowing down a little will do.

When you step on the brake-pedal, the job of generating electricity is taken on by the 50Kw motor instead. That larger size makes a big difference.

 

I can feel when the Prius is under the 50kw braking effect (foot totally off of the accelerator), and it can be felt as well when I give just a hair touch of the acclerator to let the vehicle coast or "glide", a no arrows condition where the car is going on its forward momentem with no power to the wheels or regenerative braking taking place.

Getting the most of the speed and doing long coasts and glides really adds to the MPG of the Prius. My habit of slow acceleration does not help MPG apparently, and I am having getting used to getting up to speed quickly, but the faster there, the better the MPG overall. Slow acceleration really does not accomplish much.

 

While coming down out of the Santa Cruz mountains on Hwy 9 yesterday I finally had a chance to use the 'B' mode. It worked really well. Then I got to explain to my husband how to do it.

That's one thing I love about my Prius - it's the one thing in our household about which I clearly know the most. Makes up for my limited knowledge of computers. Kinda balances things out at my house.

 

Another use of B mode is coping with the creeping "speed up/slow down" cycling on congested freeways. Instead of a steady 10mph, traffic will cycle between 0 and 15, which gets tiring on your right leg as you hope from brake to gas over and over. Instead, try B and you get braking effect when lifting the gas, much like in a stick shift. It is a lot more relaxing to modulate speed by lifting and pressing instead of moving between pedals.

 

I don't think I'll ever need to BUT a primer on the proper use of B would be helpful. Do you 1) step on brake 2) shift and then 1)step on brake 2) shift to D There's so much to learn even after reading the manual!

 

andyprius
I use a MiniScanner on a 2k3 and the normal amount of regen that I see on the hill to work is about 7-9 amps regen with out brake application, with brake up to 57 amps regen possible. Without slowing down the car noticeably you can easily get 35 amps regen. This hill is a 10% average grade and has an easy S curve in the middle of it. Normal road speed of the traffic is about 90 kmh 55 mph. If the traffic is really slowing down I'll drop it into "B"mode and not use brakes and get about 27 amps regen. Until or if we ever get a MiniScanner for the 2k4-5 models that's the best information I can offer. It will be somewhat simular but probably different is some areas because of the difference in the power generation and dissipation differences in the HSD system compared to the THD.

 

"I don't think I'll ever need to BUT a primer on the proper use of B would be helpful. Do you 1) step on brake 2) shift and then 1)step on brake 2) shift to D There's so much to learn even after reading the manual!"

None of the above. You can shift on the fly between B and D without so much as lifting on the gas. No harm, no foul! You ar enot changing gears. you are merely controlling electrons in the motor/generator, and besides, the computer controls it all, making sure you won't hurt a thing.

 

To: John and Frank, Great Feedback, that helps alot. ty

 

Frank, what I'm most curious about how much electricity the IMA system actually captures. The jump from 33kW to 50kW with my Prius upgrade was hard not to notice, many more regen-symbols. But since IMA only has a 10kW motor, I suspect the value is rather small.

By the way, the motor spec is something they no longer list anymore, most likely due to the much smaller size than the competition. I knew the day would eventually come when "kW" become important. It's about dang time! Sweet!

 

The span of knowledge is so wide here. The new and naive certainly have the right to ask and will be welcomed(I'm one of them) The experienced and knowledgable are always there, over and over again I noticed, explaining what has been explained before, patiently. Then there is the blusterer with firm, fixed and biased opinions based on Nothing! Not trying, measuring,questioning or pondering quietly; they just irresposibly say anything. They end up looking foolish. This is a great forum where the opening up of ideas is welcome and encouraged. Just my thoughts. ty

 

the amount of regen I get going down a hill w/o brakes is about 7-9 amps and MG1 is about the same output as the IMA so I would guess about the same. Mind you different battery systems may charge and discharge at differnt rates. Just a quess as I've never heard any one say anything about the IMA output.