Did a seach could not find answer. I find myselfshifting to "B" to slow down, any pros or cons to using "B" instead of regular brakes? 2010 Prius with 1300 miles (i really need to drive more)
Really no "pros" in regular driving. B-mode forces the ICE to run and continue running. If you just use regular regen braking you can better titrate the amount of braking and thus improve regeneration. Also, once your speed drops below 46mph (GenIII) the ICE shuts off...so you're not wasting energy keeping it spinning like you are with B-mode.
This question has been asked and answered many times, so if you want a lot more detail do a search. As Evan points out, B mode deliberately throws away energy. That's what it is designed to do. The only time it makes sense is when descending long steep hills where the battery will max out during regen. Unless you drive in the mountains, you won't often find a hill big enough for B to make sense. Tom
Using "B" uses the engine (ICE) to slow the car down instead of the Generator, which puts energy back into the batteries. If you want the best mileage, don't use B. B is for mountain grades, etc.
I remember when I was learning to drive (1962) and downshifted an automatic to slow down, my brother-in-law told me not to do that because you have four brakes but only one transmission. Probably still good advice.
Read here: http://www.techno-fandom.org/~hobbit/cars/b-mode.html B does waste energy to brake the car, but does also generate some energy to charge the battery and does not use a drop of fuel. The difference with normal cars, is that the Prius can actually use some of the energy that would be otherwise wasted in heat in the engine pumping air into it, to recharge, albeit not completely efficiently, the battery.
The "B" action is different at above/below 25mph (20mph on Gen2) threshold. Below the threshold, if the ICE is not running, "B" does not start the ICE and increases the regeneration. Ken@Japan
I've had the ICE spin all of the way down a 1000 foot descent from the mountains at 15 mph. This situation is exactly what B mode was meant for. Tom
There are a lot of conditions we see ICE spin on a downhill at 15 mph. For example, HV battery level is high, in the S3 and so on. To duplicate no ICE spin at 15 mph in "B" mode, shift to "B" seeing the HV battery level between 4 and 6 and in the S4 when you are driving in "D" and no ICE spin. That increases the regeneration while accelerator off. Ken@Japan
