Terminology and other Questions

Yes in the C, they are both under the back seat.



Since it is a very small battery in an awkward place, your battery cables should only be for helping someone else jumpstart the dead car.

If you go down a long enough hill, it will 'fill'. When that happens you can't put any more energy into it until you use some up, so your brakes quit doing regeneration and just heat up, like a 'normal' car.

 

Saw the battery "full" today for the first time after about 3.5 miles downhill descending about 800 ft when I already had a relatively high level of charge. I'm entirely happy with it normally having room to use the regen brakes rather than being "full".

 

Mine has never been over two bars above half, on the meter. Got about 700 miles on the car now. It will run 2 miles, or more, on the battery when at that point. I figure life is good so I am not worried about the meter. I don't make a habit of running two miles on the battery but I have checked it, as I am sure most others have.
Dan

 

So, when mine is "full" (twice daily during my commute over the hill), should I be switching to the B gear to prevent that overheating. I assume that brake heat contributes to early brake wear and replacement...

 

Just a quick clarification to expand technically; the generator motor is doing the initial vehicle deceleration in the form of regeneration until the point you request additional deceleration, in which the hydraulic brakes will assist further.

Just drive the car normally in "D".


To the OP: The battery is kept between 20% and 80% of its capacity to maximize its lifespan. As such, the battery "gauge" will never read full or empty unless there's a fault in the system.

 

Any down hill that you KNOW will fill the HV battery, use B from the top. It will keep your brakes cooler. If the brake fluid boils, then pushing on the brake pedal will not make you stop.

 

When was the last time you boiled brake fluid on the street? And the car will still stop, just not nearly as well. Most OEM brake pads [read: low-temp street pads] will fade well before any reasonably fresh brake fluid will. None of this is relevant for your average public-road driving. If you're up in the Rockies and like to ride your brakes on the many-mile long steep descents, then it's something to consider.

 

I absolutely agree you won't encounter any terrain that needs B near Detroit. (or Mississippi where I live now) We do not know where ChinchillaGirl is.

When I lived in NV and drove home to WA, I drove I-84 through OR and saw vehicles use the runaway ramps and smelled my own brakes enough to dismiss the idea that Toyota added B for no good reason.

http://cms.oregon.gov/ODOT/MCT/docs/EmigrantHill.pdf?ga=t

 

I am in California and go from 400 ft above sealevel over a 2000 ft high grade back down to 300, twice a day. I AM averaging 52 mpg even in this situation, but would love to do better, and I want to save my brakes! I appreciate any advice I can get.

 

B is never a 'better MPG' solution, it always wastes energy that D mode would not.

However you can 'fill' your HV Battery with a 600 foot vertical drop, so perhaps 1000 feet of your drop each day consists entirely of wasted energy once the battery fills. By starting to use engine braking in B mode from the top, it should be farther down the hill before the battery fills, so the brakes stayed cooler, longer. Modern brakes will not have serious trouble with overheating when new, as ryephile says, but as your brake fluid ages it's boiling point becomes lower. Boiling fluid means spongy or no brakes.

If you find that your HV Battery never fills in B mode, then you do not need B mode for that hill. You will get better MPG without it. If you had a Prius PHV, with it's larger battery, it would not fill in 1600 feet.

One oddity about engine braking, the engine gets faster and louder the more brakes you need, and slower and quieter the less brakes you need. This is not typical behavior in other cars, but is normal in this case.

(I am often accused of 'hating' B mode, I really only want it used where it will improve safety and not just squander energy)

 

Type in 'ICE' or whatever here:
http://www.cleanmpg.com/forums/glossary.php

It will tell you what it is, then search for that term to find out all (more than, actually) you want to know.

 

Thank you VERY much for that clear answer- it has given me options to consider including giving B a try at the top.

 

I don't drive a "c", but as with any Prius, wouldn't it make sense to try and deplete your battery before you crest a hill? This would serve two purposes:

- improve MPGs on the way up
- may not need to shift to "B" mode and regen normally on the way down.

Of course the configuration of the hill makes a difference. If someone is commuting every day, they could figure out the most efficient way to maximize MPGs.