Quick regen question

since regen seems to work best under 42 miles an hour.. cost down.. or.. you could use B mode to go down.. shift to D and then apply breaks with a nice steady but not too hard of a pressure when you get tot he light.

i kinda don't use B.. it takes a few moments for the car to properly get away from B mode. I don't have a canview, but the lexus does have a guage, so i toy with that car and apply it to my prius.

 

<div class='quotetop'>QUOTE(abeagler @ Aug 24 2006, 01:44 PM) [snapback]308907[/snapback]</div>

Depends if the light will be green or red when you get to it.
Also depends on state-of-charge the battery is in, and how you intend to use it afterward. If it's near your destination, no need to charge the battery, for instance. But generally, there will be some loss of energy when converting kinetic energy to battery power and back again, so if you can maintain your speed at the bottom of the hill, just coast down it.

 

If it were me, I'd probably ease up on the accellerator as you're cresting the hill, and begin coasting down it while gently applying the brakes. Whether you coast or gently brake down the hill, the energy doing either will regenerate the battery regardless. You just don't want to be coasting so fast that you have to use more force to brake harder as you approach the light thus causing the friction brakes to kick in sooner than they otherwise would if you were already going a little slower...

 

<div class='quotetop'>QUOTE(Rancid13 @ Aug 24 2006, 04:21 PM) [snapback]308985[/snapback]</div>

I think I'm just discovering this myself, Rancid13!

I also have a very long coast downhill near the end of my errand trips home....I had been coasting exclusively, and picking up speed too close to the light...which, rarely, is green or turning to green....so now, I'm applying brakes a little bit as I go down so that I don't go over 40 mph and wind up hitting brakes harder at the end.

These dang hills I live on are havoc to figure out....but I am maintaining about 41 mpg right now on second tank and VERY happy with that for the kind of driving I do.

terri

 

Rather than coasting and having to hard brake, you would be better to coast combined with a gentle braking to come to your stop.

Regen is most efficient within its ranges.... going from 60 to zero by coasting alone may make more power than covering less distance with brakeing, but sometimes that is not practicle.

But braking hard with even less distance is likely to get even less regen... so be moderate and you'll be with tolerances it was built for.

Toyota made it to do its job for normal driving.
Coasting has a 10K regen and braking has up to a 50K regen ability if I remember right, but I"m sure you could brake hard enough to regen 150K and throw everyone in the car forward if the car would regen that high, so since it can't.. just stay within tolerances.

 

I've got a hill on the way to work that is a 10%grade for almost 1 mile and what I do is use brake so you can feel it just starting to slow the car and that normally yeilds about 45-50 amps of regen. I'll hold it at this till the speed drops almost to 15 miles an hour at which point the regen drops down to 10amps. If there is a lot of traffic I'll use B and that mimicks the speed that most people drive on the hill. Now for some stats the speed limit is 30mph but most people let the speed build to 50 before applying brakes as there is a slight corner half way down. In the last year I can count on one hand the number of times I've managed to get a green light at the bottom. If I use B the regen is in the order of 35 amps with a bit of braking. The BSOC might go up 2-3% on the hill depending on traffic. Before the crest of the hill is a flat 4 block long strech if I time the light right and traffic is normal I can do the whole distance in stealth which will pull the batter down 2-3%. The battery is very tightly controlled on the Classic unlike the G2's, I've had it to 80% only on very long hills or in the summer without much stealthing around.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Sep 17 2006, 05:39 PM) [snapback]320939[/snapback]</div>

same on the wifes I can get it to 80% but not in mine. Mid 70's if I'm lucky. Starting a 55% at Rumble I'm lucky to get 58% at the light.

 

<div class='quotetop'>QUOTE(Frank Hudon @ Sep 17 2006, 07:29 PM) [snapback]320935[/snapback]</div>

Thanks Frank... thats very informative.. I've never seen anyone share thier Can-view knowledge that well.
I don't have Can-view, but at least now I know how to feather the brakes to get the most out of it.

It sounds like you get full regen when the brakes "just start to slow the car".. so that would stand to reason that applying any more brakes than that is only a waste of friction or kinetic energy since 50 is the max anyway.

 

50 amps isn't the max, close about 58 seems to be about as high as I've ever been able to get it. This data from my Classic.
CAN-view on the 2k4 shows about 125 max, that I've been able to generate. I'd have to look at the Max/Min's to see if it was higher. I've gotten it to 83% BSOC on a "hill" after getting the battery temp up to the low 40'sC. Battery voltage peaked at 248 Volts. Oh the hill was 8 1/2% grade for 8 Km's (5 miles)

 

Yeah, the Classic braking system brought in way too much hydraulic
too early in the game. Toyota documents this, as part of pointing
out how improved the 3rd-gen system is -- it basically doesn't
touch the brakes till you *really* need 'em. Much more efficient.
.
100A steady-state, btw. Maybe 125 in a very brief burst but keep in
mind the pack is *fused* at 125A!!
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ Sep 17 2006, 10:56 PM) [snapback]321054[/snapback]</div>

when the BSOC is in the 70% range and the battery is cool in the low 20C range and your on a long grade you can put 125 in till about 78% and then it very rapidly drops into the 20 amp range and once at 80% 2 amps is all I've seen. Yes it's fused but it's not a normal fast blow fuse, it's more of a slow blow type. I sure wouldn't want to give it a 10 amp surge when your up in the teens or low 20's as I'm sure you'd pop it.

 

Wow..this whole regen thing it tooo coool...

Toyota is the only one I can think of thats had the guts to master it.

Honda is just a wanna be when it comes to this stuff.

 

Drive for safety. If driving for regen increases your chances of an accident by 1% because you are no longer driving with the flow of traffic, it's not worth it.

If there are no other cars around, then go ahead and optimize your braking strategy for regen. But don't put yourself and others at risk trying to get an additional 1 or 2 % SOC into your battery. Remember that no matter what you do, you are going to recover some energy slowing down on a downhill.