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Discussion Starter · #21 ·
I have not disconnected the 12 V battery. There is no risk in doing this, I assume (first time EV owner). And regarding the 30-50% SOC cell voltages, I should be able to get those tonight after work. Any thoughts on what I've put together so far @Telek? Would you also recommend a 12 V battery disconnect to restart the system? I don't want to do anything that would jeopardize my outstanding service escalation just in case there isn't a simple DIY solution to what I am experiencing.
 

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Discussion Starter · #22 ·
Plotting the three data points I have for DIC vs Raw HD and adding a linear regression gives the following graph, which shows a theoretical 30.2% SOC when the display is reading 0%.

35459
 

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I have not disconnected the 12 V battery. There is no risk in doing this, I assume (first time EV owner). And regarding the 30-50% SOC cell voltages, I should be able to get those tonight after work. Any thoughts on what I've put together so far @Telek? Would you also recommend a 12 V battery disconnect to restart the system? I don't want to do anything that would jeopardize my outstanding service escalation just in case there isn't a simple DIY solution to what I am experiencing.
You may lose some of your settings / preferences in the infotainment system, but otherwise, it should be like restarting a computer (which it actually does).
 

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Discussion Starter · #24 ·
You may lose some of your settings / preferences in the infotainment system, but otherwise, it should be like restarting a computer (which it actually does).
Thanks. Is there any specific SOC I should do this at or does it not matter?
 

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Discussion Starter · #26 ·
Update:

I got home and did a quick scan of the car to determine the differential before I tried a reset by disconnecting the 12V battery. Here is what I saw -

DIC vs Raw HD
58.04 - 62.84 (which matches pretty closely to the correlation I posted earlier)

DIC vs Raw HD (after power cycle)
62.35 - 63.11

I will remeasure the variance in the morning after charging overnight, but it does seem to be improved based on this initial observation.
 

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Discussion Starter · #27 ·
After the overnight charging the differential grew again so I ended the charging session and disconnected the 12V battery again to restart the system. Each time the correlation between DIC % and Raw % resets to the current SOC (the intercept between actual and ideal on the graph), but the slope is remaining almost the same each time. Maybe I need to run the battery to a low SOC and do the reset again. Has anyone else had this kind of problem?

35472
 

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After the overnight charging the differential grew again so I ended the charging session and disconnected the 12V battery again to restart the system. Each time the correlation between DIC % and Raw % resets to the current SOC (the intercept between actual and ideal on the graph), but the slope is remaining almost the same each time. Maybe I need to run the battery to a low SOC and do the reset again. Has anyone else had this kind of problem?

View attachment 35472
At this point, the problem seems beyond armchair Internet expertise. You might have to take your data to a dealer and try to get them to call GM's engineering support.
 

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Discussion Starter · #29 ·
My thoughts as well. Now if I can just get through to them over the phone (multiple calls and messages). Thanks for the help and suggestions I think I have plenty of evidence at this point.
 

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Discussion Starter · #30 · (Edited)
Update from the weekend. On Friday night I ran the battery down as far as I felt comfortable watching the DIC and Raw HD % through my VeePeak OBDII reader and Car Scanner app. When I got home I did a 12V disconnect to reset the computers and left it charging all weekend (Level 1). On Sunday morning the dashboard (and MyChevrolet app both showed a full battery) - shown as Arrow 1 on the graph below. After that the Raw HD continued to climb and the DIC remained pegged at 100% - shown as Arrow 2. While this was occurring the Hybrid/EV Vehicle Charging State PID read "Charge Increasing Mode (PSA)". By 9:45 pm last night the charge had completed showing - 100% (DIC) and 97.51% (Raw HD) at which point I disconnected the charging cable and when to bed (EDIT: cell voltages were 4.16-4.17V - with only one cell showing 4.15V; and pack voltage of 398.83V). I drove the car to work this morning hoping this "recalibration cycle" would have corrected the discrepancies we have been seeing. During the drive I captured some snapshots to show there is still a major difference between the two that would indicate only about 71% of the battery would be usable if I went solely by the gauge cluster and MyChevrolet information - shown as Arrow 3 below.

35524


The good news is that I will be talking to the service director and the primary EV technician on staff within the hour to discuss the information that GM engineering has asked for. More to come (unfortunately). I will continue to keep this thread updated, as it may help in the future for other owners experiencing similar problems.
 

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Discussion Starter · #31 ·
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%.

59.71 * 0.8549 = 69.84 kWh total capacity.

Just before lunch I went to move my car to the back lot at work and the DIC % corrected back to closely match the Raw HD % (from 67.06 to 74.51). Maybe it will just take more charge-discharge cycles to get back to full, usable, indicated capacity.

1623091301269.png
 

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Discussion Starter · #32 ·
After a commute home. And again, after a few hours parked the difference between DIC and Raw HD is corrected.

35536
 

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Discussion Starter · #33 ·
After a first half of today's commute. The differential between DIC and Raw HD when I reached the parking lot was 20.2%.

35550
 

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Discussion Starter · #34 ·
OK, after two days commuting to work I traveled 209.1 miles expending 68.3 kWh and here is the final charge and this is the final SOC graph for the charging prior and the discharge cycle during the commutes.

35572


The low range can probably be attributed to the Michelin CrossClimate2 we have switched to. Based on my experience with the switch from LRR to the Michelin CC tires on my Prius I estimate that the additional consumption is about + 40-50 Wh/mile (- 0.3-0.4 miles/kWh) compared to the baseline.

I will have to see after the charging cycle over the next 24 hours if the differential between DIC and Raw HD closes up. I have a feeling it won't during usage, but realigns after 1-2 hours parked (which is what happened between these four drives).
 

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OK, after two days commuting to work I traveled 209.1 miles expending 68.3 kWh and here is the final charge and this is the final SOC graph for the charging prior and the discharge cycle during the commutes.
It's an interesting exercise, but I'm not sure I see the point of it. The car has an algorithm for converting its internal sensor readings into a displayable "state of charge" and "miles remaining" estimate. It seems like what you're trying to do is akin to lifting the cover to see inside the algorithm - but to what purpose?
 

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Discussion Starter · #36 ·
It's an interesting exercise, but I'm not sure I see the point of it. The car has an algorithm for converting its internal sensor readings into a displayable "state of charge" and "miles remaining" estimate. It seems like what you're trying to do is akin to lifting the cover to see inside the algorithm - but to what purpose?
It all goes back to gathering data to prove to GM that after the HPCM2 replacement that my indicated range and usable capacity plummeted (which it did). Has anyone else on here parked their car (without charging) and come back a couple hours later to see their charge percent went up substantially (up to 20%)? Or charged for 12 hours (L1) after the GOM already showed a full charge (under this "Charge Increasing Mode (PSA)??
 

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It's an interesting exercise, but I'm not sure I see the point of it. The car has an algorithm for converting its internal sensor readings into a displayable "state of charge" and "miles remaining" estimate. It seems like what you're trying to do is akin to lifting the cover to see inside the algorithm - but to what purpose?
I think the issue is the wide divergence between SOC Displayed and SOC Raw, and, as a @KyleBrightman noted, large changes after parking (without charging). Looking at the chart, note the curve when he goes from ~55% SOC Raw to ~32% SOC Raw. In that same drive, the SOC Displayed went from ~54% to ~12%. Then, after being parked (without charging), the SOC Displayed jumps back up to ~31%. Something is broken.
 

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It all goes back to gathering data to prove to GM that after the HPCM2 replacement that my indicated range and usable capacity plummeted (which it did).
I can understand taking it in to the dealer and saying "I filled the battery, drove it to zero, and the car reports that it only got xx kWh out of the battery" - that's something that's pretty straightforward and incontestable. But the dealership isn't going to have the faintest idea of what to do with the PID information and I guess I'm just skeptical that you're going to find a path to get the information to someone in GM who (a) trusts it and (b) would know what to do with it.
 

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I can understand taking it in to the dealer and saying "I filled the battery, drove it to zero, and the car reports that it only got xx kWh out of the battery" - that's something that's pretty straightforward and incontestable. But the dealership isn't going to have the faintest idea of what to do with the PID information and I guess I'm just skeptical that you're going to find a path to get the information to someone in GM who (a) trusts it and (b) would know what to do with it.
No PIDs necessary. Just drive it, take a photo of the SOC bars on the left side before it's parked, then another photo after it's parked, revealing 4 additional bars without having charged the vehicle. Or screenshot the MyChevrolet app before and after parking. No dealer service tech can explain away an extra 20% of battery charge showing up without actually charging the vehicle. Also, he noted in post #30 that GM engineering has asked for additional data.
 

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No PIDs necessary. Just drive it, take a photo of the SOC bars on the left side before it's parked, then another photo after it's parked, revealing 4 additional bars without having charged the vehicle. Or screenshot the MyChevrolet app before and after parking. No dealer service tech can explain away an extra 20% of battery charge showing up without actually charging the vehicle. Also, he noted in post #30 that GM engineering has asked for additional data.
Obviously I haven't been following the saga closely enough, that's my bad!
 
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