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Discussion Starter · #1 ·
I've had my 2019 for about 21 months now and I have noticed a weird problem that is difficult to explain.

Ever since I bought to car I have noticed that about every fourth or fifth day that I drive it the mi/kWh goes bonkers after about 5 miles of driving. I most do slower, in town driving, so it settles in at about 5.5, then over the next few miles skyrockets to 15 or 20. I have seen it go as high as 35! It stays there after several miles of driving, then slowly falls back to the normal range after 25 miles or so.

I am absolutely positive that this is not something that I am doing, as the area I live in is generally pretty flat and my slow, pokey driving style does not deviate much.

After a few months of this I took it to the dealership and they tested the battery and assured me everything was fine. I do have the paperwork they gave me that documents that I reported this, and since the fire situation is not resolved I have been taking a picture every time it happens, in possible hopes of a buyback.

Does anyone have any insight as to what this could be? Apparently the dealership doesn't and with this fire situation I'm afraid I'm in a rolling tinderbox.

TIA

Rick Malek
 

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When you say the dealership tested the battery, did they test the high power traction battery, or the regular car 12V battery? Other owners have reported weird electronic or software issues when the 12V battery is losing its capacity.

You can "reset" the Bolt's computer by temporarily disconnecting the 12V battery. You may lose some of your settings and need to re-input them.
 

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Mine did that once after a DC charge. I pulled away from the charger and the miles per kwh went laughably high, i think well into the 20s. I reset the trip a few times then after about 15min of driving it went back down to normal.
 

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Ever since I bought to car I have noticed that about every fourth or fifth day that I drive it the mi/kWh goes bonkers after about 5 miles of driving. I most do slower, in town driving, so it settles in at about 5.5, then over the next few miles skyrockets to 15 or 20. I have seen it go as high as 35!
In your examples, you're just not driving far enough for the car to get an accurate read. Any down slope (and your one screen shot is in full regen) will cause it to jump up. Stop resetting and let it keep a running total and it will be more accurate.
 

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Tell what are the temperatures of the battery and ambient when it happens.
I had this happen on my daily commute where there are no hills that could explain it.

Normally, I get 4.5-5.2 on this 10 miles trip, but sometimes, after charging, I get as much as average of 16 miles/kWh and the 5-mile bar graph is shooting up to 24.
The explanation for mine is ambient temp and the battery temp.
I had disconnected the charging before the battery finished conditioning, so it was still warmer, while ambient was cooler. It cooled off when driving and somehow the energy "was added".
It is just some computer behaviour.

As for yours, if that is not it, then it must be the terrain.
 

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Are you holding the OK button to reset the stats? When you do that, mi/kWh resets to 3.9 but depending on how you drive and the amount of regen being used, it can go squirrely for a few miles before it gets enough data.

Mike
 

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I've had my 2019 for about 21 months now and I have noticed a weird problem that is difficult to explain.
The date label is covering up some vital information in that first picture. Without seeing the odometer mileage, we cannot know how far you have gone between the two pictures. I assume you have reset the trip odo in between, but can't be sure.

In any event, I have never seen mi/kWh numbers like that in four years of driving our Bolt.
 

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When do you reset it? If you aren't doing it until after you're already moving you've let the system ignore the amount of energy it took to get up to speed. That can be a lot depending on what your drive is like.

I've never reset mine so I can't say if it carries this same behavior.
 

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For reference, I also have a 2019. I've had mine do this a handful of times. After completing a charge overnight for the first 10 to 20 miles it'll show 10 to 15 mi/kWh. Even driving on the interstate (70 mph) for that first 10 to 20 miles it wouldn't make the mi/kWh drop below 10 when it did it. Might be some kind of software glitch. The ambient temperature didn't make a difference for me. It happened twice in the winter (below 20 degrees) and all other times were 80 degree plus days.
 

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Discussion Starter · #13 ·
In your examples, you're just not driving far enough for the car to get an accurate read. Any down slope (and your one screen shot is in full regen) will cause it to jump up. Stop resetting and let it keep a running total and it will be more accurate.
Respectfully, I just don't agree with that. I reset the trip meter every morning before leaving the driveway. I track my mileage for tax purposes, so this is something I always do.

Granted, the first few miles the meter could certainly be all over the place. I watch it like a hawk. Sure when I first get rolling it might be super low, and maybe after I roll up to the first stoplight it might peg a little high. This does not start until I am generally several miles into my day, at which time one or two minor variations in terrain would not have that massive of an effect. It settles out at around 5.5 mi/kWh then skyrockets.

Again the two pictures I have taken only are the past two times, because I am trying to document these incidents. I have seen it go above 30 mi/kWh!!!! Unless I'm rolling down Mount Kilimanjaro, that should be absolutely impossible.

Also, my work takes me all over the place, but I generally start my day in the same area, which is just about completely flat.
 

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Respectfully, I just don't agree with that. I reset the trip meter every morning before leaving the driveway. I track my mileage for tax purposes, so this is something I always do.

Granted, the first few miles the meter could certainly be all over the place. I watch it like a hawk. Sure when I first get rolling it might be super low, and maybe after I roll up to the first stoplight it might peg a little high. This does not start until I am generally several miles into my day, at which time one or two minor variations in terrain would not have that massive of an effect. It settles out at around 5.5 mi/kWh then skyrockets.

Again the two pictures I have taken only are the past two times, because I am trying to document these incidents. I have seen it go above 30 mi/kWh!!!! Unless I'm rolling down Mount Kilimanjaro, that should be absolutely impossible.

Also, my work takes me all over the place, but I generally start my day in the same area, which is just about completely flat.
I would agree that there is definitely something to it. The only constant variables I could track was that all instances happened after a longer charging period and all were overnight charges in my case. The trip meter was also reset every time prior to driving; when it happened. It definitely stated 3.9 mi/kWH when reset, but quickly jumped up to the 10 mi/kWh plus within a few miles. It jumped up even when already at interstate speeds. In both winter instances the efficiency also increased when the vehicle was setting with the heat running and pulling power.
 

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After driving EVs for over twenty years, I can confidently point out that the vast majority of strange behaviors out of them is due to a weak 12V PbA auxiliary battery.
 

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After driving EVs for over twenty years, I can confidently point out that the vast majority of strange behaviors out of them is due to a weak 12V PbA auxiliary battery.
I could see that. I will point out I've never had any issues with low voltage on my 12 volt battery and it's never been replaced. Couple questions and observations.

1) How low of voltage does it have to be to cause issues and/or strange behavior?

2) Wouldn't it trigger an alert on the vehicle?

3) It has happened in both 20 degree weather and 80 degree weather and follows a pattern of heavy charging periods.


I'm reluctant to suggest an auxiliary battery issue based on the variables and patterns. Although, I am curious about how often the auxiliary battery pulls from the main battery and if it changes based on the charge times. Also, I believe the Bolt auxiliary battery is AGM.
 

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1.) Surprisingly high (still in the low 12V range, in some cases).

2.) Not necessarily, as the 12V system is responsible for the error message system power, and is itself subject to low-voltage error strangeness.

I'm just sharing my experiences that a weak 12V battery is notorious for causing strange behaviors in EVs.

Being a somewhat cheap thing to "fix", it makes sense to go after it first. A relatively inexpensive 12V charger/maintainer would be a good investment anyway, as they can be used on any vehicle's 12V battery to keep it healthy. Just make sure it's designed for an AGM PbA, as their charge profile can be a little different that a run-of-the-mill PbA.
 

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1.) Surprisingly high (still in the low 12V range, in some cases).

2.) Not necessarily, as the 12V system is responsible for the error message system power, and is itself subject to low-voltage error strangeness.

I'm just sharing my experiences that a weak 12V battery is notorious for causing strange behaviors in EVs.

Being a somewhat cheap thing to "fix", it makes sense to go after it first. A relatively inexpensive 12V charger/maintainer would be a good investment anyway, as they can be used on any vehicle's 12V battery to keep it healthy. Just make sure it's designed for an AGM PbA, as their charge profile can be a little different that a run-of-the-mill PbA.

There is another post with a lot of information about the 12 volt system in the Bolt if any one is interested.

Auxiliary battery issue/pattern does seem more likely after reading through details and how the charging system works.
 

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I had to replace the AGM 12V on my 2017 recently. The indication was a bunch of intermittent "unable to charge" messages. The dealer check the codes and it was showing low voltage.
 
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