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Discussion Starter · #41 ·
Put another way:

As my car sits right now charging at 27% (according to MyChevrolet/DIC) it shows 37 miles of range, which works out to be 137 miles at 100% SOC (37 / 0.27 = 137). This despite my last full charge showing 3.1 miles/kWh (which assuming 60 kWh usable would seem to indicate 186 miles of range).

The highest I have seem my GOM since the HPCM2 is 156 miles at 100% SOC
 

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Discussion Starter · #42 ·
Update: Just talked to the shop foreman since it was Monday (4 days ago) that I got them the additional information that was requested by engineering. They said they would like the car in to do a data dump in order to diagnose the problem. I said absolutely I'd like to get it to you ASAP (tomorrow, Saturday) and I will need a loaner car. He said of course and we have a couple Bolts on the lot, we will have one ready to go for you. Seems like I'm getting a bit of the royal treatment now (last time I was put in a miserable Trax - what a punishment - and I'm shocked its MSRP is right at the purchase price I had for the Bolt).

4/27 - Original service light came on
5/7 through 5/12 - In the shop getting HPCM2 replaced (6 days)
5/25 - Back in shop to diagnose capacity problem (1 day)
6/12 - Will be dropped off for data dump (will likely be completed during the week of 6/14)

I'll let you all know how it goes.
 

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Discussion Starter · #43 ·
Update: Got a call this morning from my dealer that my car is ready and can be picked up. They have a bunch of data to share from the data dump, that I will look at with an open mind. The corporate folks said if we were doing short drives and charging it every night (we were doing neither) then the system would not have a chance to properly calibrate. He also stated that it would take at least 4 charge cycles starting below 25% in order to learn the battery extents (I can guarantee we did that at least 4-5 times in the past three weeks). There were no issues identified or addressed based on the data they collected. He also stated that the range hit (-32 miles) was contributed by a combination of tires (Michelin CrossClimate2) and AC usage. I didn't argue over the phone that 259 - 32 = 227 miles (NOT the 156 mile GOM range at 100% I've seen since the HPCM2 - and this is the highest number I saw).

The one hope I have is that the last charge-discharge-charge cycle I did before dropping it off did the trick. Evidence - on the way to the service department on Saturday the differential between Raw HD and DIC was the smallest I have seen since I started measuring it (91.37 vs. 90.64) and when I first started up in the morning it had the little bit of upper buffer (100 vs. 96.57).

Time will tell and I'll keep this thread updated.
 

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One more addition is that the charge from 12.02 % (Raw HD) to 97.51 % (Raw HD) took 66.34 kWh at the wall. Assuming an efficiency of 90% for the charging it put 59.71 kWh into the batteries to raise the SOC by 85.49%.
L1 charging has quite a bit more than 10% losses. I think 17% is typical but there is a pretty big range, making that inferential test suspect. You are better off going to a public L2 charger like Chargepoint or SEMA and deducting 12% from the kWh delivered from their meter.

I don't have a lot of confidence in your method because I am not sure the SoC reporting is accurate. So while I suspect a defective pack, the 'proof' is not solid. I suggest instead that you use the above mentioned public charging to go from 2.8 to 4.12 volts average cell voltage. It will take time, but it will be a better test. The pack voltage is 96 * average cell voltage

Perhaps related, If you have a weak cell, it would be exposed by a histogram of cell voltages at a low SoC.

Good luck !
 

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Discussion Starter · #45 ·
The lowest SOC I have seen was 7.78% (Raw HD) and all the cells were between 3.38-3.40 V with no outliers. I'll soon be hooking up my Clippercreek Share2 32 amp L2 chargers and can repeat the process.

3.38 V: 3
3.39 V: 90
3.40 V: 3
 

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The lowest SOC I have seen was 7.78% (Raw HD) and all the cells were between 3.38-3.40 V with no outliers. I'll soon be hooking up my Clippercreek Share2 32 amp L2 chargers and can repeat the process.

3.38 V: 3
3.39 V: 90
3.40 V: 3
The problem for most people with home L2 chargers is measuring kWh. If yours is hooked up to a meter or you have a CT you are good to go.

That is a good distribution, and not consistent with a defective cell. Was it before or after the repair ?
I'm not sure if 3.38 - 3.40 volts is typical for a SoC of 8%. You can google the discharge curve of Li-x cells since they are all pretty close. Or perhaps someone will post data from their car.

Addendum:
This chart agrees with your SoC and voltage reading, so you can do the test from ~ 3V with reasonable accuracy
 

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Discussion Starter · #47 ·
The problem for most people with home L2 chargers is measuring kWh. If yours is hooked up to a meter or you have a CT you are good to go.

That is a good distribution, and not consistent with a defective cell. Was it before or after the repair ?
I'm not sure if 3.38 - 3.40 volts is typical for a SoC of 8%. You can google the discharge curve of Li-x cells since they are all pretty close. Or perhaps someone will post data from their car.

Addendum:
This chart agrees with your SoC and voltage reading, so you can do the test from ~ 3V with reasonable accuracy
It was after HPCM2 replacement and before taking the car back in for follow up with the escalation.
 

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Discussion Starter · #48 · (Edited)
The documentation was a bunch of stuff I already knew (pack/cell voltages, etc). The GOM was reading 125 miles (156 max, 105 min) at 100% SOC when I picked it up and the line to the left of the GOM was pegged at the top in green the whole drive home. The 16 miles home used only 6% charge with heavy AC usage (extrapolates to 266 miles range). They recommended to drive until the SOC is below 25% before charging again (should not be a problem), so hopefully the GOM returns to sanity after the next cycle.

EDIT: By the way they did nothing but read codes and determine that everything is normal and well within spec.
 

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Discussion Starter · #49 ·
The first drive to work used a reasonable percentage of charge (both DIC and Raw HD). The GOM started by saying 125 miles and after 51 miles of driving showed 118 miles of range. Seems like the next charge cycle might make everything match up nicely. Also, the drive had an efficiency of 3.6 mi/kWh which is better than I have been experiencing lately (since changing to the CrossClimate2 tires).
 

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Discussion Starter · #51 ·
DIC is the percentage you see on the dash or the MyChevrolet app

Raw HD is the behind-the-scenes actual battery percentage
 

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DIC is the percentage you see on the dash or the MyChevrolet app

Raw HD is the behind-the-scenes actual battery percentage
Both are based on a decision by the engineers who built the car. The cells in the Bolt could be charged to 4.400 volts without bursting into flames. Is that the average cell voltage Raw 100% is based on? Who cares? 4.165 volts average is the voltage 100% DIC is based on. Raw may figure into some of the range, and SoC calculations, but it is a fiction, as we will never actual get to use it.
 

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Both are based on a decision by the engineers who built the car. The cells in the Bolt could be charged to 4.400 volts without bursting into flames. Is that the average cell voltage Raw 100% is based on? Who cares? 4.165 volts average is the voltage 100% DIC is based on. Raw may figure into some of the range, and SoC calculations, but it is a fiction, as we will never actual get to use it.
I may be mistaken but I think these values differ not just in theoretical max and min or nominal, but also in partial discharge states.
 

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I may be mistaken but I think these values differ not just in theoretical max and min or nominal, but also in partial discharge states.
My point is that there is only the actual cell voltage. It is a percentage of some imagined maximum, and minimum. What we do know is the highest and lowest cell voltage that GM allows us to use. As long as your Bolt can reach those voltages, who cares what percent of Raw it is, if your GOM readings, and Ah capacity numbers, are back to normal?
 

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Discussion Starter · #57 ·
@GJETSON @bolt-ish I agree with both of you, but if I continued to trust my indicated state of charge on the dash and in the app and charged it to 90% as needed (when the charge got below 20%) would my car have ever learned the true extents of the battery or would I have had a perpetual perceived limitation of 52 kWh of usable capacity? And why has it taken nearly 1400 miles of driving to get back to its original behavior?
 

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Discussion Starter · #58 ·
Another update, still experiencing the same stair step behavior of state of charge as in Post 34. The GOM is still saying 156 miles at 100% SOC after at least 14 round trips to work (101-106 miles per). I have ran the battery down to single digits at least four times and followed with uninterrupted recharges. The car simply is not relearning its limits and range. I still experience an SOC bump after being parked for two hours (yesterday after my drive to work while in the parking lot it went from 9% to 27%). Really not sure how this is going to resolve itself, on the plus side at least it's been escalated in GM and I have a service record to refer to so maybe I can start talking directly to engineering instead of my local service folks.
 

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Another update, still experiencing the same stair step behavior of state of charge as in Post 34. The GOM is still saying 156 miles at 100% SOC after at least 14 round trips to work (101-106 miles per). I have ran the battery down to single digits at least four times and followed with uninterrupted recharges. The car simply is not relearning its limits and range. I still experience an SOC bump after being parked for two hours (yesterday after my drive to work while in the parking lot it went from 9% to 27%). Really not sure how this is going to resolve itself, on the plus side at least it's been escalated in GM and I have a service record to refer to so maybe I can start talking directly to engineering instead of my local service folks.
Keep us posted. When they last took it in, did they actually do anything besides diagnostics? (Reinstall the software update, replace the computer, etc.?)
 
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