[icydog]

With ACC enabled, the van will auto-brake to slow down with the car ahead of it. But even when the braking is relatively heavy, my hybrid monitor app doesn't go any lower than about -10 kW even when I estimate it should be around -30 to -50 kW based on how hard it's braking and the highway speeds. Anyone else notice this? It seems it's mostly using the friction brakes instead.

 

[Dpacifica]

I had not noticed that, but use ACC all the time so I will try to pay more attention. I hardly ever use the friction brakes. I was counting on basically never having to get a brake job like our Prius, but if the ACC is using the friction brakes more, that would be a bummer


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[BlueTect]

Is there any indication on the instrument cluster when friction brakes are being used?

 

[icydog]

Is there any indication on the instrument cluster when friction brakes are being used?

I haven't seen anything like that. The closest thing to it that I've found is that the regen shown will be less than expected for the amount of braking being applied.

 

[Dpacifica]

I tried ACC this morning in city driving (45mph) and got -34kw regen at one point. I have seen higher with braking while going down a hill or having to stop quickly, but it definitely was not limited to -10 on ACC as you describe. Were you driving while it was raining? The manual indicates that the friction brakes will be used more in wet conditions; although I have no idea why.


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[icydog]

I tried ACC this morning in city driving (45mph) and got -34kw regen at one point. I have seen higher with braking while going down a hill or having to stop quickly, but it definitely was not limited to -10 on ACC as you describe. Were you driving while it was raining? The manual indicates that the friction brakes will be used more in wet conditions; although I have no idea why.

Hmm, I don't think I've ever seen ACC deceleration get up to -34kW. Maybe it's just me? Regarding wet conditions, that's because regen braking is limited to the drive wheels (of which there are only two) but friction brakes are on all four, so it's more stable.

 

[Dpacifica]

Ok, makes since you need the friction brakes when wet I guess if it can't regen from all four wheels.


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[livininspirit]

ACC works the same as normal brake pedal. it simply commands the car to slow down. The hybrid controller then determines when to use regen braking and when to use friction braking.
Most of the time, the car will use regen brake to decelerate. Friction brakes are only used in the last few mph or hard braking requests to really hold the car.

With my Prius, I had over 125K miles on the original brakes. They still had 50% life left after that. It rarely used the friction brake to slow the car down since it doesn't need to. that's why this car gets good MPG. it's recovering otherwise wasted energy. Love it.

A quick fun fact, this weekend, i was driving down from skyline blvd (in the bay area) going on Page Mill back to Los Altos. I was able to recover 12% battery, assuming 14khw usable battery capacity, i recovered 1.67kwh. To put into perspective how much energy that is, an iPhone 7 holds about 7wh of energy. I recovered enough energy to charge the iPhone 7 over 238 times!

 

[icydog]

ACC works the same as normal brake pedal. it simply commands the car to slow down. The hybrid controller then determines when to use regen braking and when to use friction braking.

Is this from your empirical experience, or how it *should* work? I understand ideally this is what happens, but it doesn't seem to match what I've been observing.

 

[livininspirit]

ACC works the same as normal brake pedal. it simply commands the car to slow down. The hybrid controller then determines when to use regen braking and when to use friction braking.

Is this from your empirical experience, or how it *should* work? I understand ideally this is what happens, but it doesn't seem to match what I've been observing.

Yup I use ACC all the time. It definitely uses regen to slow down the car. It behaves exactly the same as if I was pressing the brake pedal. Now under certain circumstances regen won't work: batttery is full, battery temperature too high or low, etc. but once again that's the job of the hybrid controller with batter management system

 

[cerrmj]

I just returned from a 1200 mile trip. Used the ACC almost all of the time while on the highway. I was very impressed with the smoothness of it, especially when accelerating back up to speed after slowing down for traffic. My '06 Sienna had ACC and it would mash the accelerator and sometimes kick down a gear to get back up to the ACC set speed as quickly as possible - and most of the time overshoot. The Pacifica accelerated back to speed gently and didn't overshoot.

I can tell you that regen does work while using ACC - I was fascinated while watching the power indicators during driving. Go down a hill - the ICE turns off and you get some regen going to keep the speed where it is set (instead of just accelerating down the hill like the Sienna with ACC did). Going up the next hill - the E-motor kicked on to get you started up the hill before the ICE started up again to help. It if was a long hill - I sometimes saw the battery charge go up 1 or 2 percent. I was surprised and impressed by how much the e-motor was used while driving in Hybrid mode which I'm sure was why I got about 30MPG on the trip with 5 adults, luggage and stuff for the beach loading us down.

 

[icydog]

I just tried this again, and with ACC on, braking from 80mph to about 35mph, the highest I saw it go was about -35kW. With that kind of braking, regen should easily reach -85 or -90kW. I definitely feel like it's limited in ACC mode. What's the highest regen someone has seen with ACC on?

 

[ScorpyMjolnir]

I've been watching it the last few days. It definitely uses the friction brakes much more than I would on ACC. ACC tends to brake much later and harder than I would. It's great on stop and go arterials heading home, but I'm not sure I want to use the extra bralkes and lose the regen. hrmmm.

 

[hillgiant]

Does it make a difference if you are in D or L?