[obermd]

On Saturday I had to go up to Evergreen, CO for a wedding. Left home with a full charge and returned with 9 miles left on the battery. It was a 54 mile out and back (same roads in both directions) round trip and included a 2,000 ft. climb from my home. My normal commute is 50 miles (peak elevation is 500 ft. higher than home) and I usually end up with 10-13 miles EV range left.

The key to range in the mountains is L combined with cruise control. L provides some serious power regeneration to keep the car at the cruise control set speed while descending. I saw regen numbers close to 50KW on the way down on the steeper slopes.

I was in Normal mode the entire way.

 

[flyingsherpa]

..... I saw regen numbers in close to 50Wh on the way down on the steeper slopes.

Sounds like your regen is broken...

(sorry, pet peeve)

 

[obermd]

Edited the "in" out of the regen figures. Obviously regen shows as a negative number in the car because the car considers using battery a positive. I wrote it as a positive because it was in regen.

 

[lagagnon]

Yep, regen is amazing. Coming down 1100m from Mount Washington alpine resort in L to near sea level over a distance of about 15 km added 44 km to our range estimate.

 

[JoeReal]

I saw regen numbers close to 50Wh on the way down on the steeper slopes.

the largest regen that I have seen is -52kW going downhill. So theoretically, the battery can be recharged at 50 kW without a problem.

 

[hellsop]

the largest regen that I have seen is -52kW going downhill. So theoretically, the battery can be recharged at 50 kW without a problem.

I wouldn't do it for routine charging. Lithium Ion batteries don't really like charge rates faster than 1C (where C is pack size / time, which is really convenient because you just drop the "h" part). And 50kW is about 2.5C for a Volt. That's a little rough on the lifespan, even with good thermal management. (Mountain Mode charging, for comparison, is about 0.75C.)

 

[JoeReal]

I wouldn't do it for routine charging. Lithium Ion batteries don't really like charge rates faster than 1C (where C is pack size / time, which is really convenient because you just drop the "h" part). And 50kW is about 2.5C for a Volt. That's a little rough on the lifespan, even with good thermal management. (Mountain Mode charging, for comparison, is about 0.75C.)

So 18.4 kW charging is okay with the Volt? I would try to keep my regen at 18.4 kW...

 

[JRRF]

The key to range in the mountains is L combined with cruise control. L provides some serious power regeneration to keep the car at the cruise control set speed while descending. I saw regen numbers close to 50KW on the way down on the steeper slopes.

What is the value of having it in L if you are using cruise control? The ACC will control your speed using regen braking with or without L.

 

[obermd]

What is the value of having it in L if you are using cruise control? The ACC will control your speed using regen braking with or without L.

First, I don't have ACC. Second, ACC won't provide any more regen than normal cruise control.

What L does in this situation is it instructs the car to switch over to the low speed motor (I have a gen 2) as quickly as possible when starting down a hill. Two items occur when this happens. First, engine braking will maintain the set speed and the car won't accelerate down the hill. The second is that the low speed/high torque electric motor is used for power regeneration. I have experimented and on downhill stretches where my car shows -4 to -5 KW regeneration in D it will show two to three times this in L. This difference in regen holds true even on downhill stretches where D also maintains the set speed.

 

[JoeReal]

First, I don't have ACC. Second, ACC won't provide any more regen than normal cruise control.

It does for my case especially when I encounter traffic. I can't seem to match the way the ACC brakes for me efficiently and how it accelerates gently seldom going into yellow indicator. If I take over the speed to simulate cruise control, as soon as I hit traffic, I always get yellow no matter how seemingly gentle I accelerate or deccelerate.

 

[obermd]

It does for my case especially when I encounter traffic. I can't seem to match the way the ACC brakes for me efficiently and how it accelerates gently seldom going into yellow indicator. If I take over the speed to simulate cruise control, as soon as I hit traffic, I always get yellow no matter how seemingly gentle I accelerate or deccelerate.

Accelerating to avoid yellow is definitely an art form.

 

[JRRF]

I have experimented and on downhill stretches where my car shows -4 to -5 KW regeneration in D it will show two to three times this in L. This difference in regen holds true even on downhill stretches where D also maintains the set speed.

This is fascinating, and confusing. If the car speed is maintained equally in D and L, how is the energy being dissipated in D if it is not going into regenerating the battery?

 

[obermd]

This is fascinating, and confusing. If the car speed is maintained equally in D and L, how is the energy being dissipated in D if it is not going into regenerating the battery?

When in D the high speed electric motor is also being used, which doesn't recharge the battery. In L only the low speed electric motor is being used during regen. Only the low speed electric motor recharges the battery.

 

[JRRF]

When in D the high speed electric motor is also being used, which doesn't recharge the battery. In L only the low speed electric motor is being used during regen. Only the low speed electric motor recharges the battery.

So the high speed electric motor just dumps the energy it creates keeping the car at speed?

 

[quirkySquirt]

First, I don't have ACC. Second, ACC won't provide any more regen than normal cruise control.

What L does in this situation is it instructs the car to switch over to the low speed motor (I have a gen 2) as quickly as possible when starting down a hill. Two items occur when this happens. First, engine braking will maintain the set speed and the car won't accelerate down the hill. The second is that the low speed/high torque electric motor is used for power regeneration. I have experimented and on downhill stretches where my car shows -4 to -5 KW regeneration in D it will show two to three times this in L. This difference in regen holds true even on downhill stretches where D also maintains the set speed.

I'll have to test this tomorrow. Are you sure it's not that L is working harder to maintain your cruise control speed? If I go down a steep enough decline in D, I will regen but also gain speed. If I switch to L I get more regen but stay rock solid at my set cruising speed.

 

[hellsop]

When in D the high speed electric motor is also being used, which doesn't recharge the battery. In L only the low speed electric motor is being used during regen. Only the low speed electric motor recharges the battery.

I am confused about this "high speed motor" and "low speed motor". Which one is MGA and which one is MGB?

 

[obermd]

I'll have to test this tomorrow. Are you sure it's not that L is working harder to maintain your cruise control speed? If I go down a steep enough decline in D, I will regen but also gain speed. If I switch to L I get more regen but stay rock solid at my set cruising speed.

And you don't get a speeding ticket from the nice Morrison, CO police officer sitting at random spots on the descent either. I'm convinced Morrison, CO gets the bulk of their revenue from C-470 and US-285.

 

[quirkySquirt]

So, I've tested on my hilly commute to and fro and can't seem to get more regen when using L over D when on flat ground. On a downhill where L can maintain my speed, I definitely get more regen in L. On same hill when I switch to D, I get less regen but I'm also increasing in speed despite having cruise control set. Soon as I shift to L again, I get a brief surge of regen as the extra speed above where my cruise is set and while holding at the set cruising speed, I do get 2-5 times more regen depending on how steep the hill I'm on and what speed I'm going.

On flat ground, I see no regen at all in D or L. At best, I see a 0.5 kW instantaneous power consumption.

 

[limbery]

So, I've tested on my hilly commute to and fro and can't seem to get more regen when using L over D when on flat ground. On a downhill where L can maintain my speed, I definitely get more regen in L. On same hill when I switch to D, I get less regen but I'm also increasing in speed despite having cruise control set. Soon as I shift to L again, I get a brief surge of regen as the extra speed above where my cruise is set and while holding at the set cruising speed, I do get 2-5 times more regen depending on how steep the hill I'm on and what speed I'm going.


My L and D work like the above without ACC on but when I've got ACC on it holds like a rock to whatever speed it's set too regardless of going up or down hill...it just gets a lot of regen when going down hill. ('17 Volt)

 

[obermd]

So, I've tested on my hilly commute to and fro and can't seem to get more regen when using L over D when on flat ground. On a downhill where L can maintain my speed, I definitely get more regen in L. On same hill when I switch to D, I get less regen but I'm also increasing in speed despite having cruise control set. Soon as I shift to L again, I get a brief surge of regen as the extra speed above where my cruise is set and while holding at the set cruising speed, I do get 2-5 times more regen depending on how steep the hill I'm on and what speed I'm going.


My L and D work like the above without ACC on but when I've got ACC on it holds like a rock to whatever speed it's set too regardless of going up or down hill...it just gets a lot of regen when going down hill. ('17 Volt)

I suspect the ACC is switching internally to L as needed to maintain speed. Remember, I don't have ACC.