Regenerative brakes versus friction (regular) brakes

It dawned on me today that anytime we're in regen braking only, we are only being slowed down by the front wheels, not all 4 as when traditional brakes are applied.

 

Too bad Toyota does not show Regen vs Friction brake iindication on the graphic display. Would be a nice feature.

 

This is one feature I'm very excited about Dave offering at CoastalETech.com. It's one of only a handful of things I think that should be included with the car that weren't. Hopefully Dave's mod is affordable and easy to install!

-m.

 

Dumb question when reading this thread:

Does this mean that we won't have to replace our brakes as much if we use regen more than friction?

First, my service tech says that I don't have to replace the oil as much (since it runs less), next I learn that there is no steering fluid to deal with.

This is working out to be one of the BEST car ever!

 

I pulled out my hardcopy of the Toyota THS II Technical Spec. This document is worth its weight in gold. I got a copy from my boss who I believe purchased and downloaded it from the Toyota technical site. I'd really like to see this document in the Files section...

Anyways, the spec shows two torque curves side by side, comparing the THS I system (in the 01-03 Prii) to the new THS II system. In THS I, there was always some hydraulic braking coming into play to supplement the regen braking. A slight tap on the brake pedal would first engage the hydraulic brakes, and then use regen braking upon further pedal depression. In THS II, the regen braking power range has been greatly expanded so that now it is almost exclusively the only means for braking. If I interpret the torque curve literally, in THS II the hydraulic brakes ONLY engage upon fully depressing the brake pedal. Anything short of that will exclusively regen brake. Note that the braking system, as controlled by the ECB module, is activated by a brake pedal stroke sensor, which trips any time you touch the pedal.

Given all that, unless you're a complete digital driver (full accel, full brake only), your brakes and pads should last an incredibly long time!

 

Also, According to the 2004 New Features Manual:

The engine coolant in the '04 is most likely the Toyota Genuine SLLC (Super Long Life Coolant), which is pink in color. This fluid does not need maintenance on it until the car reaches 100,000 miles for the first time, and then subsequently every 50,000 miles afterwards. In the 03, it was every 30,000 miles or 24 months, whichever comes first.

-However, it does state that it's possible that the car does have a mixture of the two, which means maintenance after 30k or 24 months. Does anyone know how to check and see what coolant you have in your Prius?

-m.

 

If you car has been sitting a while after a rainstorm, you can usually hear the brake pads scraping away oxidation on the rotor. It's a mild grating sound that disappears quickly. However, you can use these opportunities to "test" the point at which the friction brakes engage. With your Prius in stealth mode (the EV switch is great for this), you can clearly hear the point at which the "humming" of re-generation gives way to the "grating" sound.

Surprisingly, it takes more pressure than I would have guessed to engage the friction brakes.

 

I plan on sticking pretty close to getting the oil changed every 3 thousand miles or so just to stay on the safe side. The ICE in the Prius cycles on and off so much that on shorter trips, it may not have enough heat built up in it to burn off condensation that forms in the engine.

 

The car's manual says every 5000 miles, and the car itself will remind you every 5000 miles. That's the "safe side" number. 3000 miles just keeps the profits high for the oil change folks, really.

The manual also says that the car should use 87 octane gas, but I'd be willing to bet there are a lot of people who use 89 or 93 "just to be on the safe side" even though they have no idea what that would keep them safe from...

 

Being a loyal viewer of MPT's Motorweek TV show for 20 plus years, I've picked up a number of helpful hints from their resident mechanic Pat Goss. Not that he is the final word on what is absolutely right for anyone's particular circumstance, I find that his advice will pretty much apply to the mainstream driving public. He has said numerous times on Motorweek as well as on his local radio show that the oil itself doesn't lose it's lubricating ability with mileage, it's the fact that the additives diminish with time, use and mileage and eventually cease their effectiveness as you put on the miles. 3000-3500 miles for city/suburban area driving has been his recommendation for oil change intervals and the logic in his explanations make sense to me.
MPT's Motorweek: http://www.mpt.org/motorweek/carcare.shtml

 

Disclaimer: I DIDN'T TELL YOU TO DO THIS
But...
I found that after a typical drive without too many hills, I can touch the front discs and not get burned. In fact, on some occasions, they are only mildly warm.

 

Simply because of the further refining required higher octane gas usually has less sulfur in it, roughly 100 ppm versus 200-300 ppm for 87 octane. This means it is somewhat less polluting. I use 93 octane when explicitly low-sulfur gas is not available.

 

Indeed, in the Netherlands the cheapest gas has octane 95 (Euro 95 it's called) and we also have 'Super' which has 98 octane.

Shell just introduced Shell V-Power ™, it can be used in cars that normally tank Euro 95 and it has no sulfur in it (according to Shell). Actually if you read more on this 'amazing' fuel, it has less than 10 mg of sulfur per kilo gas.

 

Partly a safety issue. It would tend to distract you during braking, which is a pretty dangerous time. Especially if the car in front has ABS or suddenly increases its braking force.

 

I wonder what dash-display lawsuit has tainted Toyota's view of what we can look at. If it's so darn distracting, why can we look at ANYTHING?

They should go back and put in a two-stage powerup sequence.

1) Foot on brake and push Power button.

2) Read the "Nothing I see on this screen will distract me, I swear!" message on the screen and hit its OK button.

3) Car activates, you drive off.

That way, we could have radio station messages and all kinds of stuff, without being baby-sat anymore. I mean, really, isn't what's already there fairly distracting, if you LET it be?...