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

3K views 30 replies 12 participants last post by  Wrover 
#1 · (Edited)
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.
 
#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.
 
#6 ·
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.)
 
#8 ·
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.
 
#9 ·
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.
 
#18 ·
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.
 
#19 ·
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)
 
#25 · (Edited)
Yes, once you have recovered sufficient energy through regen the battery indicator bars will light up. Each bar represents 10% of the available 14.1kwh battery capacity ~ 1.41kwh or 5.3 miles of range. If you are driving in Mountain mode or Hold mode your Volt will be operating in Charge Sustaining (CS) mode as you descend. If you are in Normal mode and the battery is depleted your Volt will switch to CS mode. As you start to recover energy into the battery the gas motor will stop running for as long as there is sufficient charge in the battery to maintain the desired speed.
 
#30 ·
I actually kinda miss this fine tuning. FYI, in the Bolt, once you set cruise regen defaults to L behavior regardless if you're in D. So when going downhill with cruise set and while in D, you no longer gain speed and instead gain more regen. If I switch to L down hill with cruise set on my Bolt, no difference in speed or regen. Volt IMO is superior in options for the hypermiler.
 
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