[schaeferamy]

Hey all, Newbie here. Searched hours for this topic. Sorry in advance if I missed it. I edited to make clarifications, as suggested.

Nov 2016 took 2012 Volt to dealer for intermittent issues w/ braking in L. I live on a big ridge; it was coasting down hill, picking up speed in L & starting back up next hill in L w/ feet OFF pedals (I tested to see if the car could coast up that small hill when L engaged properly, & it slowed to a crawl). Mainly occurs just after leaving house w/ full range. The curious thing is I've driven car this route 47mos w/o this issue in L, knowing when to toggle b/t L & D to p/u max miles (it was a game when car was brand new to stretch the range 50 to 53). When serviced, problem didn't occur, so they did nothing.

Since, L failed to decelerate the car several times, once approaching a rotary; quite unsettling b/c I expected to slow & wasn't sure if it was or not by the feel of it, then awkwardly braked w/ pedal.

Last week I had GPS repaired & asked to check braking in L again. Tech notes referred to green ball in the middle when accelerating & braking, which indicated the tech doesn't know what to look for. Nothing was done, so I called back. They put tech on speaker to trouble shoot. They called GM & spoke w/ engineer who wants me to record charge & temp if it occurs 3 more times. L failed to decelerate today starting at full charge & 60 Fahrenheit & continued to fail decelerating the car while in L for 12 miles. On the return trip, the feature returned to normal.

Have any of you had this issue repaired? What to do if it won't fail to decelerate when they test drive it for a few minutes? I'm 1600 miles away from 75k miles & my warranty expiring. If it's actually a glitch, I want it fixed before that happens. Thanks!

 

[llninja]

You really need to clarify what you mean by L failing several times. Are you saying that while in L, the expected deceleration lets loose and you start to coast as if you are in D or N? or are you actually pressing the brake pedal while in L? You need to be more clear or else we're just all guessing.

I have had several times where I'm decelerating in L, hit a bump in the road, because of the slight wheel spin, it disengages L regen cycle and flashes a dashboard light showing that you've lost traction. If you were regenning hard and felt this, then it is normal behavior. It happens more with worn tires than brand new tires.

I would also contend that driving in L doesn't necessarily give you better range. You want to minimize regen rather than maximize it. I've reverted from experimenting in L to driving in D and using the brakes. Most of the time the brakes gives you a smoother stop, variable regen, and only engages the friction brakes at the end of your stop. It is also less jerky jerky for your passengers.

 

[wordptom]

Nov 2016 took 2012 Volt to dealer for intermittent issues w/ braking in L. I live on a big ridge; it was coasting down hill in L & starting back up next hill in L (impossible if working properly). Mainly occurs just after leaving house w/ full range. I've driven car this route 47mos w/o issue in L, knowing when to toggle b/t L & D to p/u max miles. When serviced, problem didn't occur, so they did nothing.

If you start down a long hill with a full charge, you may reach a point where regen has filled that small buffer above the full-charge state of charge level. If you continue downhill, there will be no regen (and because you’re no longer recharging via regen, i.e., Electric Mode driving, you’ll probably start adding Gas Miles). Friction brakes will work. Others may advise you on how the Volt operates when the max upper SOC level has been reached while driving downhill, but it may, indeed, feel like you’re coasting downhill and up the next hill while the shifter is in L.

 

[bentbiker]

You want to minimize regen rather than maximize it. Most of the time the brakes gives you a smoother stop, variable regen, and only engages the friction brakes at the end of your stop. It is also less jerky jerky for your passengers.

If you start down a long hill with a full charge, you may reach a point where regen has filled that small buffer above the full-charge state of charge level. If you continue downhill, there will be no regen . . ., but it may, indeed, feel like you’re coasting downhill and up the next hill while the shifter is in L.

+1. Try stopping the charge at 95% or do a temperature conditioning before you start and I'll bet you don't have the problem.

 

[saghost]

As the others have said, there are two conditions that occur during normal operation which result in little or no regeneration, and it kinda sounds like you might be hitting them.

GM included a small buffer above the point that charging stops to give you normal regeneration with a full battery, but it's only a couple hundred watt hours so if you start at the top of a hill you may easily overcome it.

As llninja pointed out, if the car detects any wheelspin, it immediately cuts all regen for a couple seconds and flashes "Low Traction" on the DIC. I used to get that on a lot of rough corners even in dry weather if I hit them just wrong.

Maybe there's something wrong with your car, but so far I'm thinking you just managed to hit a few of the corner cases.

 

[llninja]

In other words, everything's under control, situation normal

 

[Norton]

It's hard to follow some of your post.
You don't gain anything performance wise driving in L vs. D.

For example: I came down Pikes Peak riding the brake pedal in D just like a dumb tourist. Stopped at the Park Ranger Safety Station.
My brakes were 75* on a 65* day. The SUV's brakes in front of me stunk to high heaven.
I got the biggest, fastest regen charge to ~75% possible in America!

Maybe you were talking about 'Hill-Top' charging. Don't do that.

 

[Loboc]

Kind of hard to follow this OPs discription of the "failure". Since OP is indicating a difference in the car's operation in "L" whilst having a full charge and going downhill, it sounds like the normal limiting of regen in this particular situation. Kind of strange that it would occur after 4 years of driving.

 

[ClarksonCote]

As others point out, L will only "hold you back" until the battery gets completely full, then it will coast like D. The other time "L" will stop slowing you down is if you hit a bump in the road, then a "Low Traction" message will appear and the regenerative braking will temporarily disengage.

The other point to make is that your post seems to infer that the vehicle can't accelerate up a hill when in L, though I could be misinterpreting you. In the Volt, "L" is no different than "D" for accelerating. You can go 100mph in L, or stay in that gear all the time. The only difference is that it will actively try to reduce your speed when you're not pressing down a lot on the accelerator, assuming the battery has room to recapture that energy. The only time the battery won't have room to recapture energy is if you have a full charge and start down a longer hill. In every other scenario the battery will have plenty of buffer to capture this energy.

By the way, Cruise control + L is a really great experience in hilly areas, because it will keep the speed you set when going up hills AND down them, i.e. holding the car back with the regenerative braking that L employs automatically. This will work in virtually every scenario, except steeper hills at slower speeds. At highway speeds though, it's a really great experience.

 

[Norton]

.....
By the way, Cruise control + L is a really great experience in hilly areas, because it will keep the speed you set when going up hills AND down them, i.e. holding the car back with the regenerative braking that L employs automatically.

Correct.
This is one of the best reasons to use L !!

 

[jbakerjonathan]

It's hard to follow some of your post.
You don't gain anything performance wise driving in L vs. D.

For example: I came down Pikes Peak riding the brake pedal in D just like a dumb tourist. Stopped at the Park Ranger Safety Station.
My brakes were 75* on a 65* day. The SUV's brakes in front of me stunk to high heaven.
I got the biggest, fastest regen charge to ~75% possible in America!

Maybe you were talking about 'Hill-Top' charging. Don't do that.

I hope to make a visit to Pikes Peak this year. I will drive up in CS mode. My plan is to engage CC and L and descend. Is it mandatory to make a stop at Glen Cove during the descent? Any words of wisdom?

 

[Norton]

I hope to make a visit to Pikes Peak this year. I will drive up in CS mode. My plan is to engage CC and L and descend. Is it mandatory to make a stop at Glen Cove during the descent? Any words of wisdom?

Arrive at the summit with no EV range.
Don't 'Hill-Top Charge'
Spend some time at the summit. Watch for the cogged railway to arrive. Have a picnic ! Dress warmly.
Everyone stops at the Ranger Safety Stop. Smile and ask him to read your back disc temps too.

CC and L.
Riding the Brake pedal in D.
The results are the same.

 

[ClarksonCote]

I hope to make a visit to Pikes Peak this year. I will drive up in CS mode. My plan is to engage CC and L and descend. Is it mandatory to make a stop at Glen Cove during the descent? Any words of wisdom?

I think (hope) you want to drive up in CD mode (charge depletion) rather than keeping a full charge until you're at the top in CS mode. Or if your battery is already dead at the bottom, then using CS mode to the top is okay.

 

[2VoltFamily]

The OP posted this on our facebook page as well with similar responses. The only thing I would add is that I use to also drive in L all the time. Then I did an experiment and found that if I just drove in D and mastered the art of coasting I achieved better range. L is nice for one pedal driving.

So there are trade offs. In the end we found Drive to be the best for us.

 

[canehdian]

CC and L.
Riding the Brake pedal in D.
The results are the same.

Maybe for the car, but not the human driving it...

 

[Norton]

Maybe for the car, but not the human driving it...

Well, it's not a straight road, obviously.
You will not be alone on this road
And then there are tourists dumber than the one in the Volt.
You will be using the brakes/regen. But I managed to not use the friction brakes. Without even trying.
That's the moral of this story.

This is not an ordinary drive in the country.
I've done it!
ENJOY !!

 

[jbakerjonathan]

I think (hope) you want to drive up in CD mode (charge depletion) rather than keeping a full charge until you're at the top in CS mode. Or if your battery is already dead at the bottom, then using CS mode to the top is okay.

Actually, I will have driven over 1800 miles in CS mode by the time I get to the base of Pikes Peak. I don't plug in when I am on road trips. So, I'll be driving up with the ICE-Gen providing current. When I descend, my plan is to keep at the speed limit by descending while in L and using CC. Hopefully, I won't have to step on the brake pedal until I reach Glen Cove Inn. As Norton says, effectively, there is no difference: both will use regen to impede forward movement. But my preference is to let the car do that work. I will stop at Glen Cove and have the Ranger measure the temps of both front and rear brakes - for bragging rights. Does anyone know how full the battery will get? And, I guess the battery miles I drive afterwards until the ICE-Gen kicks in again will not improve the ICE mpg datum (conservation of energy, and all that).

This has probably been discussed at length over the years, but, I don't recall the results. Is there any action on my part before depleting the battery charge gained in the descent, such as shutting down the car for a given period of time, that will confuse the algorithm into believing the charge came from wall charging? I'm thinking that I might have lunch after the descent and I don't want my stats screwed up.

 

[hellsop]

Actually, I will have driven over 1800 miles in CS mode by the time I get to the base of Pikes Peak. I don't plug in when I am on road trips. So, I'll be driving up with the ICE-Gen providing current. When I descend, my plan is to keep at the speed limit by descending while in L and using CC. Hopefully, I won't have to step on the brake pedal until I reach Glen Cove Inn. As Norton says, effectively, there is no difference: both will use regen to impede forward movement. But my preference is to let the car do that work. I will stop at Glen Cove and have the Ranger measure the temps of both front and rear brakes - for bragging rights. Does anyone know how full the battery will get? And, I guess the battery miles I drive afterwards until the ICE-Gen kicks in again will not improve the ICE mpg datum (conservation of energy, and all that).

This has probably been discussed at length over the years, but, I don't recall the results. Is there any action on my part before depleting the battery charge gained in the descent, such as shutting down the car for a given period of time, that will confuse the algorithm into believing the charge came from wall charging? I'm thinking that I might have lunch after the descent and I don't want my stats screwed up.

Have you seen the road? Or like videos of the climb? If not, I recommend looking at some and tell me if you think the normal cruise control will be appropriate, especially in light of the practical bottom end of 25 MPH.

 

[jbakerjonathan]

Have you seen the road? Or like videos of the climb? If not, I recommend looking at some and tell me if you think the normal cruise control will be appropriate, especially in light of the practical bottom end of 25 MPH.

No and no. Perhaps I will find that 25 mph in CC and L is too fast for the curves. And, as Norton has pointed out, there may be other tourists for whom I'll have to brake. My plan is to not drive off the road!