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First post! I've been lurking for a couple months now and I'm really thankful to everyone here sharing their experiences.

Dark Grey, 33k miles on it.
Luckily the previous owner hadn't reset the trip counter in about 32k miles so i'm able to posit that the lifetime mi/kWh is 3.4! (Which seems fairly average?)

At first I was wary of buying a used EV, as most people probably are before doing much research, but after looking through thread after thread of people praising the Bolt's bullet-proof drive system and better than expected battery performance, I put those worries aside.

After driving it around town for a few days we decided to try out a longer trip. It was an out & back trip, 180 miles total. We were worried because after charging the car to full (turned off hilltop reserve for this trip), the GOM told us we would get 170 miles of range.
Reading a few threads on here had me thinking that the GOM was probably low-balling and the estimate would adjust as we went, and besides, there was a DC Fast charger on our route that we could stop at in case of catastrophe.
At mile ~130 we stopped at the Fast Charger with 37 miles left on the GOM. So it actually turned out to be really accurate for this trip.

It was about 45F I believe, was a bit windy, the route was flat, 95% interstate driving at 65-70mph, and we kept the climate controls low. So I was thinking that the less than ideal weather mixed with interstate speed was the cause of the lackluster range performance.

Fast forward about a week later, i've been taking short trips around town with it, and the weather has even been nicer (50-70F). After a week of 'recovering' from the long trip I figured the GOM would recalibrate the estimated range but it actually seems to be getting worse.

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It's fully charged (with hilltop reserve re-enabled) and the range estimate is 139 (max 164). This got me concerned so I got myself an OBD2 adapter and sure enough, my "Estimated Battery Capacity" reading is 44kWh.

And so now i'm here with the question: Did I buy a lemon? :(
 

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It does sound like you might have a bad cell or cells. Since you have the OBD2 adapter, I would suggest taking a look at the voltage of the individual (96) cells to see if you can spot one or more cells that are lower than the rest. I suspect you will and if so, that should trigger a battery/module replacement. Until you have more info, you might want to charge/park it outside.

Mike
 

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I hope You got a good deal on it , The 2017's sure seem to have taken a severe "Nestea plunge " in depreciation the last year or so. Do You feel comfortable sharing with the forum how much You paid?
 

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Don't panic yet. It looks like the miles/kWh has never been reset? Go ahead and reset and drive for 100 miles or so. Then show us a pic of the miles/kWh and also the screen like you did in your original post.
Also, what kind of OBD2 adapter did you use to read "Estimated Battery Capacity"?
 

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I hope You got a good deal on it , The 2017's sure seem to have taken a severe "Nestea plunge " in depreciation the last year or so. Do You feel comfortable sharing with the forum how much You paid?
$19,000 usd
 

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Don't panic yet. It looks like the miles/kWh has never been reset? Go ahead and reset and drive for 100 miles or so. Then show us a pic of the miles/kWh and also the screen like you did in your original post.
Also, what kind of OBD2 adapter did you use to read "Estimated Battery Capacity"?
Used the LELink^2 adapter with EngineLink app (iOS because the adapter wouldn't connect to any of my Android devices) using the PIDs linked all over the place on this forum.

Just reset the trip a couple days ago and will keep an eye on it.
 

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How much pressure are in those tires. I run mine at 40lbs. I think the spec is 37lbs.

Also, how is your driving style? I keep to the speed limit around town and actually use the cruise to keep the speed steady and from rising. I coast to stop lights using 'D' and avoid using regen as much as possible. (Moderate hypermiling). We're getting around 240-ish on the GOM with full charge. (Yesterday I set hilltop mode on due to the recall though, so that will drop.) I did some errands yesterday with the windows slightly open and no climate control and got about 5 mi/kwh for a while. The speed limits were running between 35 to 45 mph.

Are you on the freeway a lot? Hills? Do you have hilltop mode turned on? On the freeway I run at or slightly below the speed limit depending on whether or not I am in a hurry.

At 3.4mi/kwh times the 60kwh pack your range calculates out to about 204 from full charge to zero. That's a bit low, but depends on so many factors. If you drive it sporty like some people do with ice then your mileage will drop.

Finding out if you have a bad cell is a good thing if your OBD2 will do that for you.

With all of these tools you should be able to figure out if your reduced range is due to equipment or pilot. Good luck.
 

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Discussion Starter #12
How much pressure are in those tires. I run mine at 40lbs. I think the spec is 37lbs.

Also, how is your driving style? I keep to the speed limit around town and actually use the cruise to keep the speed steady and from rising. I coast to stop lights using 'D' and avoid using regen as much as possible. (Moderate hypermiling). We're getting around 240-ish on the GOM with full charge. (Yesterday I set hilltop mode on due to the recall though, so that will drop.) I did some errands yesterday with the windows slightly open and no climate control and got about 5 mi/kwh for a while. The speed limits were running between 35 to 45 mph.

Are you on the freeway a lot? Hills? Do you have hilltop mode turned on? On the freeway I run at or slightly below the speed limit depending on whether or not I am in a hurry.

At 3.4mi/kwh times the 60kwh pack your range calculates out to about 204 from full charge to zero. That's a bit low, but depends on so many factors. If you drive it sporty like some people do with ice then your mileage will drop.

Finding out if you have a bad cell is a good thing if your OBD2 will do that for you.

With all of these tools you should be able to figure out if your reduced range is due to equipment or pilot. Good luck.
Thank you for the post!
I've been babying it since I got it, driving like a granny haha. I turned on hilltop mode due to the recall but it was already guessing low beforehand.

I'm going to check the cell voltages today.
 

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Looking at cell voltages is best. Range can be an early indicator of a problem: like if you charge to 80-100% and end up with 50 miles of range. But generally, range should be ignored if you are trying to see if the battery is OK. The only thing that matters is kWh used: charge it up and drive it down as low as you are comfortable with. Then look at the starting SOC, ending SOC, and the kWh used. That will give you an idea of how the battery is doing and it won't matter how you drive or even if you have knobby mud tires on it.

Mike
 

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I'm going to check the cell voltages today.
Definitely check all 96 cell voltages. Find your highest reading, and lowest reading cells, and set up a screen with those on either side of the average cell voltage . If there is a 0.030 volt spread between those two, at 5% SOC or higher, you are looking at a bad cell.

I agree with The Other Tom. The historical mi/kWh is only of general interest, and is just what my monthly emails from GM show for my lifetime use. It is much more useful, and informative to reset you trip odo before each drive. This will tell you much more about your driving style, and battery health, than a dusty three years worth of average data.

11-15-20 leaving 2.jpg
 

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Discussion Starter #15
Definitely check all 96 cell voltages. Find your highest reading, and lowest reading cells, and set up a screen with those on either side of the average cell voltage . If there is a 0.030 volt spread between those two, at 5% SOC or higher, you are looking at a bad cell.

I agree with The Other Tom. The historical mi/kWh is only of general interest, and is just what my monthly emails from GM show for my lifetime use. It is much more useful, and informative to reset you trip odo before each drive. This will tell you much more about your driving style, and battery health, than a dusty three years worth of average data.

View attachment 31744
Thanks for chiming in, I really appreciate the constructive input.
Just finished checking the cell voltages. I am using EngineLink (iOS) so excuse my different layout.
My methodology was as follows. While sitting in the bolt, system On, I went through all the cells and pulled out two of the lowest compared to the average. Then I did the same for the high end. This gave me this readout (again, while sitting still with the car on)
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So the readings were indeed 0.03V apart from each other.

Then I started a screen recording and took a drive around my (moderately hilly) neighborhood. Watching the video back the voltage lows dropped as low as 3.79V but the highs dropped as well and the voltages remained no further than 0.03V of each other.

Unfortunately my battery wasn't fully charged when I went to drive it this morning so I wasn't able to do the "Energy Used vs % SoC Lost" calculations. I will follow up with a drive and get those calculations after I get the car back to full. (Don't have a L2 charger yet so it takes quite a while)
 

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View attachment 31749

So the readings were indeed 0.03V apart from each other.

Your high and low cells are in the same parts of the 1-96 series as most everybody else's. Sadly, you are in the "knew battery section needed" group. You are joining an alarmingly growing group on this forum.

As I have speculated before, I suspect these are not newly failing cells, for the most part, but cars with new owners who drive farther, or are more tuned into their cars, to realize something is amiss.

When you do get to do a capacity test drive, I will not be surprised if your usable capacity is right in line with the Battery Capacity PID.
 

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On the 2017 there is a PID that tracks it, here is a link to a thread and some data others have captured
after the 2017 GM made the PID encrypted, so no longer visible except to the service tech.
I'm surprised the range is reduced as much as it is with only a .03V variance. All of the others we have seen have had variations that were way out of spec before the range dropped that low (like .2V or more). Also, with only 2 decimal places of resolution, the variance may not be .03V. It could be as low as .021V and still give the same readings shown.

Mike
 

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Discussion Starter #19
I'm surprised the range is reduced as much as it is with only a .03V variance. All of the others we have seen have had variations that were way out of spec before the range dropped that low (like .2V or more). Also, with only 2 decimal places of resolution, the variance may not be .03V. It could be as low as .021V and still give the same readings shown.

Mike
I'll try to find an android device that'll connect to my OBD2 adapter so that I can use Torque Pro because I don't think EngineLink will show any more than 2 decimal places.
 
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