How well does CC regulate speed @ 26mph &steep decline hill?

[cashcow]

Have not checked this today, but I was thinking about this and every time I use CC it does seem to do a good job at regulating speed by using regenerative braking. So it got me thinking... has anyone tried to do a trip down a super declined hill with CC @ 26 mph to see just how well the CC unit can handle it?

I know for a fact that when you are speeding at 70 + MPH and hit B then let go off the accelerator you end up getting a ton of regen bars, if not all of them. Yet, you can be going at a much slower speed, like, 30 and only get a couple of bars when you get your foot off the accelerator and hit B.

So I'm wondering here just now... if you are going @ 26 mph and turn on CC ... it will use regen to maintain speed ... but if you hit a super long super declined hill... just how much regen gets applied to maintain speed?

I have not checked this but does the rav4 ev EVER use the brakes to maintain speed for CC?

If it doesn't use the physical brakes then... what happens when you set the vehicle to such low speed (26 mph/w CC) and suddenly go down a very declined hill? I guess the car will try to maintain speed, but how much regen gets applied to achieve this? Will the speed in the ODO start CLIMBING if the car isn't able to apply enough regen to slow the vehicle down and maintain speed? Or will it start applying physical brakes?

This is interesting to me because I believe I've been in some hills that were so declined that even when using B the car still picked up speed. No CC on.

Part of that is that You get less regen as your car slows down. Less Bars with less Odo Speed. I don't know if this is just software or if the car isn't able to physically apply as much resistance to slow the vehicle down at slower speeds... for whatever possible physics reason....

Yet when I test drove model S a few years back I was surprised at just how much resistance regen provided when going down a hill. It literally felt like the physical brakes were being used.

So, I am wondering if anyone has tried doing something like this?

Mainly I want to know if say... CC is able to maintain speed @ 26mph even during a deep decline on a hill... then... you hit B thus disengaging CC and ... boom!... less regen bars and car starts to speed up.

If true... then this would confirm some sort of regen software cap?

 

[TonyWilliams]

Regen is limited to 120 amps in "B" mode, and 60 amps in Drive.

The cruise control never uses the vehicle brakes.

 

[cashcow]

Hi Tony,

Thanks for dropping that line in. I recall you mentioning that before. Highly informative!

What exactly does each Regen bar represent? Is it amps being applied? Or Energy being regenerated? Each bar representing some value of energy? Do you know how many bars are in total on the regen gauge? I've actually never counted them before and I figured it would be hard to since you'd have to be going fast to see them all pop up.

Have you ever tested CC @ 26mph going down a really declined long hill? Is CC able to hold speed under such circumstances through regen breaking? During FWY driving CC does a good job at holding speeds through quick drops on FWY roads. I just wonder how well it can hold speeds under a very declined long hill drop. I think I know a good hill to test this... I'm just waiting for a good day to do it.

 

[davewill]

If the hill is steep enough, the car will pick up speed, but it works fairly well for me going down a long stretch not far from my house. The downhill (45mph) is not terribly steep, and sometimes flattens out for a bit, and I never have to intervene to hold speed.

 

[TonyWilliams]

Sorry, I'm not sure what the regen bars represent. I don't assume power, but it could be anything... even made up data.

 

[cashcow]

I checked my self and CC can't keep speed the set speed if the hill is steep enough downwards. It looked like it had only as much regen available as you can get in B mode since I did both tests with B and CC it looked like you got the same amount of regen.


I guess the next test would be putting on really tiny tires and see how regen works with them on. It looks like you get a pre-set amount of regen based on speed on the odo because you always seem to get the same amount of regen at certain speeds. So it seems to be speed based. smaller tires would make it seem like you are going faster when you really are not. I guess it would help when slowing down at lower speeds.

 

[n3ckf]

if i go down hill i use B rather than CC to hold speed. (becuase it works better).

B turns the cruise control OFF though, so you cant use CC while in B mode. (which seems like it should work, they just locked it out for some reason).