Test-drove a Bolt twice today (LT and Premiere)

[michael]

For many people, it was necessary to keep 80 mile class cars at or at least near full charge most of the time. One of the advantages of the Bolt is that for most people it will be possible to operate over a narrow range of charge and rarely if ever fully charge. This should provide greatly increased battery life.

Unfortunately, Chevy, unlike Tesla, has not provided a charge limit slider control to make this easy to do. People who wish to limit charge levels will need to rely on workarounds.

 

[user 387]

Well, the easy work around is to simply turn on Hilltop mode and limit charges to 90%.

There are other way more complicated ways to limit the charge to other levels below that, but 90% ought to do the trick.

 

[michael]

Well, that's easy but not too good because it is 90%. Much lower is better for battery life.

 

[SeanNelson]

Well, that's easy but not too good because it is 90%. Much lower is better for battery life.

The curve is doubtless steepest nearest the 100% charge state. Therefore there would be far less additional benefit at 80% compared to 90% than there would be at 90% compared to 100%.

 

[SeanNelson]

What is "L", or what is it supposed to stand for?

The question of the day!
It isn't "Low". Anyone have an appropriate "L"-word?

My Prius C uses "B" for "Brake" mode. I think that's probably appropriate for the Bolt EV as well.

 

[EldRick]

Unfortunately, the car comes with "L".

Our task is to determine what it stands for; what word beginning with "L" could it mean.....?

 

[phil0909]

Unfortunately, the car comes with "L".

Our task is to determine what it stands for; what word beginning with "L" could it mean.....?

I'm not clear on why you have taken up this task. The Bolt EV Owner's Manual published by General Motors explicitly says that the L does stand for Low. This is stated on page 30 and elsewhere.

Are you rejecting the word "Low", but accepting the initial "L" and looking for a more satisfying L-word? Or were you just unaware that GM has already officially defined L as Low?

:?:

 

[LeftieBiker]

The problem with using the word "Low" for increased Regeneration mode is that it incorrectly implies a change of gearing or reduction of power, when neither of those actually happens. It's understandable why they don't use "R" for "Regen" (it isn't a "Reverse") but not using "B" is just GM being stubborn.

 

[user 124]

There are other way more complicated ways to limit the charge to other levels below that, but 90% ought to do the trick.

Do you know of a link for how to do that? It would be nice to set the max SOC at a different level.

 

[CGameProgrammer]

I was mistaken about charging and battery lifetime. I had done more research a little while ago and while you definitely don't want to keep a lithium-ion battery at 100% charge unless you use it immediately (but ideally never have it at 100%), it sounds like frequent partial charges are perfectly fine. In retrospect this makes sense because obviously regeneration is an extremely frequent very partial charge.

So I guess it's fine to charge the car every day, but definitely don't fully charge it unless you really need maximum range such as for a long trip.

 

[gpsman]

There are other way more complicated ways to limit the charge to other levels below that, but 90% ought to do the trick.

Do you know of a link for how to do that? It would be nice to set the max SOC at a different level.

If you drive a pretty fixed route / routine you could simply use time of day charging. You will learn that xx minutes of charging gets to to about yy% SOC.

Then just tell the car to start charging xx minutes before you leave.

Frankly, I feel pretty good about the hilltop reserve thing. As long as it is 90%. Do we know that for sure or is this just rumor / guess? It could be higher.
10% or 6 kWh of regen is a pretty long steep hill. Doubt you could get 6 kWh of continuous regen.

Hilltop reserve may be 95% or more in reality.

Call 6 kWh 23 miles.
Where on earth can you lay into the brake for 23 continuous miles? Driving from a ski resort (10,000 feet) to Denver (5000 feet) is about a 23 mile trip downhill.
But you are COASTING most of that way, not applying the brake and getting regen.

 

[Zoomit]

Hilltop reserve may be 95% or more in reality.

Others have reported Hilltop mode stops the charge between 87% and 90%.

 

[Schnort]

Driving from a ski resort (10,000 feet) to Denver (5000 feet) is about a 23 mile trip downhill.
But you are COASTING most of that way, not applying the brake and getting regen.

Actually, it's a lot of up and down, though sometimes the grade is long stretches of 6% or higher. Clearly, though, the down outweighs the up

 

[michael]

I inquired about hilltop, and received a reply from Chevrolet stating, in part...

If you are a customer who lives at the top of a hill and whose commute begins with a long downhill descent, a fully charged Bolt EV won’t take advantage of all the great regen benefit because the energy has nowhere to go. To deal with this and save customers both energy use and money, they can enable Hilltop Reserve to limit state of charge to effectively 90% SOC.

Note that this says 90% SOC, not 90% of the normal full charge level.

By the standards of 80-mile-class cars, this is a pretty high SOC. My Focus electric, for example, fully charged to 90% SOC and stopped running at 8% SOC. That car faded 22% over 54,000 miles.

So I think that to simply rely on hilltop as the every day charger limiter is risky. I intended to use workarounds (adjusting timing of charging, etc) to limit the value to some significantly lower value on normal days when maximum range won't be needed.

Perhaps we could get someone to charge to the hilltop limit, note the estimated range, continue to fully charge, and again note the estimated range. This may help us get some estimate of the full charge SOC.

I'm guessing (just a guess) that this will add maybe 10-12 miles, suggesting that the full SOC is around 95%. But a test will tell the real story....

Anybody mind giving it a try?

 

[user 124]

Perhaps we could get someone to charge to the hilltop limit, note the estimated range, continue to fully charge, and again note the estimated range. This may help us get some estimate of the full charge SOC.

Anybody mind giving it a try?

That's a great idea! Alas I do not yet have a Bolt, but can somebody else do this simple test?

 

[Zoomit]

I inquired about hilltop, and received a reply from Chevrolet stating, in part...

If you are a customer who lives at the top of a hill and whose commute begins with a long downhill descent, a fully charged Bolt EV won’t take advantage of all the great regen benefit because the energy has nowhere to go. To deal with this and save customers both energy use and money, they can enable Hilltop Reserve to limit state of charge to effectively 90% SOC.

Note that this says 90% SOC, not 90% of the normal full charge level.

Though not strictly true from an engineering perspective, I've seen SoC commonly referenced to full usable battery capacity. I would expect the "90% SOC" description from GM to be the same, a reference to 90% of the usable capacity.

The percentage of usable capacity remaining is available from the car via the myChevrolet app where it's referred to as "battery level".

 

[michael]

I'm going by what he specifically said. In any case, the test I've suggested will reveal the answer, no need to guess.

If it adds 23 miles, then yes 90% of normal full charge. If significantly less, then we will know he meant what he said.

Alternatively, if someone could l do this test and report what the app says, then we will know which is the case.

I agree with the poster above who suggested it's irrational to put in 23 miles of hilltop reserve. Unless the real purpose was to provide a limited charge option.

I'd do the test myself except no Bolt yet!


My guess (no factual knowledge) is that when we have an app that displays underlying battery parameters, we will find that Bolt uses a much higher portion of the charge window than most of us have been expecting.

If this were Vegas, I'd bet something like 95% to 5%, maybe wider. Nothing like most 80 mile cars and nothing at all like the Volt.

And for those who say "no way anyone would use that wide an SOC window", studies published on the Tesla Forums have shown that most Tesla designs (not including the software limited versions) make available 95% or more of the battery's full capacity. Which implies that the SOC at full charge must be at least 95%, possibly more.

 

[user 124]

I agree with the poster above who suggested it's irrational to put in 23 miles of hilltop reserve. Unless the real purpose was to provide a limited charge option.

Don't forget that this car strongly limits its charge current at high SOC. You might need some SOC headroom to charge with > 10 kW regenerative power.

 

[gpsman]

GREAT point tgreene!

Can't wait to test mine.
Just got a VIN # for my build yesterday.

Will have one soon!

 

[LeftieBiker]

My guess (no factual knowledge) is that when we have an app that displays underlying battery parameters, we will find that Bolt uses a much higher portion of the charge window than most of us have been expecting.

If this were Vegas, I'd bet something like 95% to 5%, maybe wider. Nothing like most 80 mile cars and nothing at all like the Volt.

And for those who say "no way anyone would use that wide an SOC window", studies published on the Tesla Forums have shown that most Tesla designs (not including the software limited versions) make available 95% or more of the battery's full capacity. Which implies that the SOC at full charge must be at least 95%, possibly more.

You are (mistakenly, I think) assuming that a SOC display would display the actual SOC. With the Leaf it displays "100%" when fully charged, despite being more like 95% charged. So the advantage isn't knowing exactly how much of the full pack capacity is in use and available, but in simply knowing that you have X% of the available charge range.