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Mountain (actually Colorado Foothill) driving isn't that hard on EV range

2154 Views 30 Replies 12 Participants Last post by  Wrover
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.
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Discussion Starter · #3 ·
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.
 

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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.)
 

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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...
 

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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.
 

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Discussion Starter · #9 ·
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.
 

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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.
 

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Discussion Starter · #11 ·
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.
 

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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?
 

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Discussion Starter · #13 ·
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.
 

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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.
 

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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?
 

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Discussion Starter · #17 ·
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.
 

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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.
 

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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)
 

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Discussion Starter · #20 ·
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.
 
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