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Just purchased a 2017 Premier! Thrilled but also a little concerned.

4K views 26 replies 8 participants last post by  MikeyBolt 
#1 ·
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.

31725


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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#2 ·
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
 
#8 ·
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"?
 
#18 ·
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
 
#11 ·
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.
 
#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.
 
#13 ·
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
 
#22 ·
OK. I have done this calculation for two other Bolts people are looking at today. Here goes again.

The Bolt with 33K miles should have 55 kWh usable. With 18 green bars it is between 90% and 85.1% SOC.

.90 x 55 = 49.5 kWh left in charge
139 mi ÷ 49.5 kWh = 2.8 mi/kWh

.851 x 55 = 46.8 kWh left
139 ÷ 46.8 = 2.97, so 3.0 mi/kWh

Neither is impossible efficiency, if somebody was driving like a hoon, and running the heat on high all the time. But I would suspect a bad cell myself.
 
#23 · (Edited)
@MikeyBolt Got Torque Pro working with my OBD2 reader and went on a short drive ~5 minute drive around the neighborhood. I logged a few of the cells that represented the high and lows I was seeing yesterday. Pulled the data into a google sheet, did a MAX(<cell voltages>) - MIN(<cell voltages>) column and then put those numbers into a chart. Not looking too good.
31766
 
#24 ·
@MikeyBolt Got Torque Pro working with my OBD2 reader and went on a short drive ~5 minute drive around the neighborhood. I logged a few of the cells that represented the high and lows I was seeing yesterday. Pulled the data into a google sheet, did a MAX(<cell voltages>) - MIN(<cell voltages>) column and then put those numbers into a chart. Not looking too good.
That's interesting, particularly the one spike. I'm not sure how to compare it to the others posted though as I don't think anyone else has looked at the data this way. Could you post an at-rest reading of all 96 cells so we can get an idea of the voltage spread when not driving? I think that'd be most comparable to what everyone else has been posting.

Mike
 
#27 ·
Yeah, that spread looks pretty similar to my 2019 with only 4700 miles on it. My spread is .021 to .022 depending on when I measure it. Nothing I see screams bad cell(s). At least at this point.

My 2019 isn't currently in the recall batch so you might be tempted to think it's better. But I see no evidence of that as it looks pretty much like what everyone else is posting.

Mike
 
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