Using B for freeway exits

I only use B mode on one hill I travel down each day which has the ICE spinning at the bottom to discharge the over charged (by Prius standards) battery anyway. I figure by burning off the excess on the way down the hill I prevent the overchage so extending the life of the battery by a few nanoseconds. I still have a few seconds of spinning ICE at the bottom of the hill but not the minute or more I get without using B mode. I always slip back into drive as soon as my speed drops to the speed limit, this suits this particular hill as it flattens out at the bottom then traffic lights which are mostly red.

 

Brakes are cheaper than engines or transmissions. I recommend using the brakes unless you are afraid of overheating them in the mountains.

 

<div class='quotetop'>QUOTE(Busta Griggs @ Sep 3 2007, 06:55 PM) [snapback]506566[/snapback]</div>

That is true for conventional brakes but not necessarily for the Prius' regenerative brakes which do use the electric motor/generator to slow down the car under circumstances such as those being discussed here.

 

<div class='quotetop'>QUOTE(patsparks @ Sep 3 2007, 09:21 PM) [snapback]506542[/snapback]</div>

The ICE spinning at the bottom of the hill is essentially B mode. By switching to it earlier on the hill, you don't save the battery from over charging, but you do potentially save some wear on the friction brakes.

Tom

 

Unless the computers are broken your Prius is not overcharging its traction battery. And if the computers were broken you'd be having a boatload of problems.

The motor/generators get tons of use anyway, including during engine braking, so what is being saved. The previous poster is correct in that the brake pedal should be used instead of fiddling with "B" on every little downgrade and exit ramp. The effect on the life of the brake pads will be unnoticeable but it will preserve fuel economy for most drivers.

 

<div class='quotetop'>QUOTE(efusco @ Aug 21 2007, 02:17 PM) [snapback]499866[/snapback]</div>

Could you explain your comment on using B below 20mph I following reading on this site never use B but would like to understand you comment better.

Thanks
Gary

 

I understand the HSD system won't allow over charge. I choose to engage B mode on the down slope rather than allow the HSD to do it anyway. If I didn't know for certain that the electric motor would be spinning the ICE at the bottom of the hill I would simply use the brakes. All I'm doing is making the inevitable happen earlier. I know the battery won't over charge in the real sense but I know the HSD will dump power from the battery at the bottom of the hill if I use brakes to control speed. By using B or engine braking mode I allow the system to dump what I know it will dump anyway without feeding that charge into the battery thus increasing the life of the battery by about 1 or 2 nanoseconds. Charging and discharging the battery in this way will only generate heat in the battery, electric motor and ICE anyway, I'm partly bypassing the battery. I wouldn't use B if I wasn't sure the HSD was going to dump power at the bottom of the hill anyway.

 

<div class='quotetop'>QUOTE(patsparks @ Sep 4 2007, 11:52 AM) [snapback]506776[/snapback]</div>

Plus it's easier on the friction brakes, assuming the hill is long enough to force them to come into play. This is exactly the situation for which B mode was designed.

Tom

 

<div class='quotetop'>QUOTE(FireEngineer @ Aug 22 2007, 12:42 AM) [snapback]500121[/snapback]</div>

the better question: When above 20mph, why bother.

 

I use "B" on long downhill grades in order to avoid using the physical brakes. That's it. Otherwise, it is just the same as regular regen breaking.

 

How many here think that Toyota put the B mode on the shifter only because they know some Americans would resist change and not understand a car without a low gear? That is my guess. Purely for marketing purposes.

Is there an easy way to know if you are using 100 percent regen braking or getting into use of the friction brakes? I always taught my family to avoid riding the brakes, but to modulate them, and if that wasn't enough, to use low gear. It seems like with the Prius, it is almost exactly opposite. seems like a steady brake pedal force that would keep the HSD in regen mode would be best.

Can anyone share how you would use brake modulation in a benificial way? And if anyone can share how to know if friction brakes are in use, other than by sense of smell?