Chevy Bolt EV Forum banner

81 - 100 of 139 Posts

·
Registered
Joined
·
8,205 Posts
Generally speaking self discharge of lithium ion is very, very low. Somewhere around 1% loss a month.

I turned off my seven Leaf module e-assist cargo bike on 03-12-20. The bike had been charged to 58.2 resting volts, and ridden 40.8 miles down to 57.7 resting volts. Thirteen months and one week later, four weeks after getting vaccinated, I turned it back on. The Cycle Analyst read 55.1 volts. I rode the bike down to the 44.8 volt cutoff. The resting voltage, after a half hour, sat at 45.5 volts.

I had put 40 Ah into the pack, per my Satiator smart charger. My last ride had used 14.9 Ah. The ride this week used 19.7 Ah. So it appears the pack lost ~5.4 Ah, or 13.5%
 

·
Registered
Joined
·
1,166 Posts
Neither of these are the case.

Lithium ion doesn't catch fire because the cell is weak or overused. They catch fire due to damage or dendrites. While continuously forcing a near dead cell to perform can drastically increase dendrites, the BMS was already way more than sensitive enough to brick your car if a cell was underperforming.
A weak cell won't burst into flames because it is weak, but if you continuously try to overcharge a weak cell, overcharging can cause a fire (without dendrites). Your statement about the BMS being sensitive enough to brick the car if a cell is underperforming has been proven incorrect here multiple times. We've seen packs where a cell (or multiple cells) varied by more than 0.5V compared to the rest of the pack and the car still worked (and charged). Typically cars in this condition (with many times the quoted .03V "allowed" variance) will have a range under 100 miles and a calculated capacity under 30 kWh. But the car still works/charges and some people have even taken them to the dealer and have been told it is "normal" only to have to prove it is NOT normal with Torque Pro.

I presume (hope) the new "advanced diagnostics" will no longer allow you to operate the car with such a huge variance in cell voltages.

Mike
 

·
Registered
Bolt EV, 2019, Premier
Joined
·
204 Posts
Disagree about the full charge delta - not at all meaningless. A bad cell will show up with the delta across the entire range, including at full, getting worse after you go below about half.
Granted, it can be way more complex my simple statement. But also, a really good cell can show just the opposite. it can exhibit lower voltage at full charge and higher voltage at low battery.

I agree with everything you have said. I think the main element missing from the broad discussion is the influence of any cause and effect data that GM or LG may have. If the data shows a decent correlation between fires and weak cells than this diagnostic is perfectly valid. Certainly a wide range of other effects COULD also be valid.

It's really all in the data and the level of risk. The potential causes and effects are so diverse that there can be almost any outcome imaginable. But, if .01% of Bolts had a battery fire and 3 out of 5 had a very weak cell. Maybe there is some correlation. We also don't know the outcome of any analysis done on cells that have been replaced.

If only .01% of cells have been replaced due to all other failures, then maybe the fire risk is even less.

I can only imagine that it all would be highly detailed and very interesting and someone would try to turn it into a giant lawsuit if it was published. So sad.
 

·
Registered
Joined
·
595 Posts
The fact that they are putting this software into all the new models makes me think (and I said this at the beginning of the recall) that a lightbulb went off in some dim witted GM engineer's brain that a true BMS, especially in a $35K+ car,
should do a lot more than just balance cells. Any BMS worth its salt will protect the batteries and the device from self immolating. GM was slumming it, period. LG may have made some defective pouches but GM should have been aware that a good BMS should "brick the car". Hence we have now what should have been from the start.

Will it be sensitive enough to detect a bad trend, time will tell. But be aware that any Li car new or old, can have a defective section as there is no such thing as perfection in manufacturing. GM has finally woken up to this.

I am happy with the fix but still won't charge to 100% inside for a least a year.
 

·
Registered
Joined
·
11 Posts
Everyone keeps conflating weak batteries with fires.

They have very little to do with each other.

If your battery has advanced degradation, it's not likely going to catch fire. This is the warranty area.

I can agree, however, that regardless of warranty status or age of the car, if GM's "advanced" monitoring software detects the situation that they believe can lead to a fire, the owner will be informed and the car will have to go in for service. Whether or not GM charges for this is up for debate.
I understand what you're saying. I just think that if the software detects an issue on an out-of-warranty battery, that GM should be on the hook for it. Having multiple vehicles go through major recalls and lawsuit settlements, I can almost guarantee that GM will agree to extend the warranty on the packs. The only question is if they only cover the major faults, or if they extend coverage for battery degradation too.
 

·
Registered
Joined
·
11 Posts
If you think many are going to let the monkeys replace just grouping of cells.... GM may be in for some more surprises. Many of the EV techs suck. You will read it time and time again here. Near me they can't get them to stay, they all leave because they don't make any money on commission with all these bolts being just warranty work
No way would I let the do that. Just replace the full battery pack and stop drinking around GM.
I was in charge of an electric fork truck fleet years ago. It's hard to find a good tech that is good at troubleshooting electrical faults, battery issues, contactors, etc.
 

·
Registered
'19 Bolt Premier; '13 Leaf SV w/premium
Joined
·
1,070 Posts
As I posted in other threads:
One new doc has appeared at Vehicle Detail Search | NHTSA. It's now at 20 associated docs. Was stuck at 19 for a long time. I think it's https://static.nhtsa.gov/odi/rcl/2020/RCLRPT-20V701-7407.PDF submitted April 29, 2021.

It is pretty vague and mentions the software (we already know about that) and:
"GM and LG Chem’s investigation concluded that the known field incidents were likely caused by one or more rare, latent cell-level manufacturing defects in design level N2.1 batteries produced at LG Chem’s Ochang, Korea facility."

"Owner notifications of the final remedy are estimated to occur in two phases; the first on May 13, 2021 to address 2019 model year vehicles and the second on May 31, 2021 to address remaining vehicles. The final remedy will be executed under bulletin N202311731. Until the final remedy is available, an interim remedy is executed under bulletin N202311730."

From the top, the estimated percentage with defect is still 1%, just like in the Feb 2021 submission.
 

·
Registered
Bolt EV, 2019, Premier
Joined
·
204 Posts
I got my 2019 updated yesterday (4/30/2021). It did take awhile. The update time is listed at 1.1 hours. With this plus the Multipoint Inspection that they always do I was at the dealership about 2 hours. Adjust your expectations accordingly. BTW, I do think that all of this effort is of value and I would be dubious of relying on an over the air update.

I have not noticed any issues so far. I can set the charge target to 100% so that looks good. Given my normal usage pattern, I will continue to charge to less than 90% unless I will need more. Normally I only charge to 60% using departure charging. FWIW
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #89 ·
I got my 2019 updated yesterday (4/30/2021). It did take awhile. The update time is listed at 1.1 hours. With this plus the Multipoint Inspection that they always do I was at the dealership about 2 hours. Adjust your expectations accordingly. BTW, I do think that all of this effort is of value and I would be dubious of relying on an over the air update.

I have not noticed any issues so far. I can set the charge target to 100% so that looks good. Given my normal usage pattern, I will continue to charge to less than 90% unless I will need more. Normally I only charge to 60% using departure charging. FWIW
Nice! Were you able to get the radio update listed in #20-NA-119 as well? (34.9.2 is the new infotainment version number for the 2019 models.. supposed to have a bunch of stability fixes). I couldn't download it on TIS2Web, but GM is moving to a new system called "techconnect" that costs like ~$3,800 a year (I'll pay $40 for 2 years of updates, but **** if i'm going to pay $3,800 as a DIYer)

My appointment is on the 11th, but our local EV certified dealership is always backed up.
 

·
Registered
Bolt EV, 2019, Premier
Joined
·
204 Posts
Nice! Were you able to get the radio update listed in #20-NA-119 as well? (34.9.2 is the new infotainment version number for the 2019 models.. supposed to have a bunch of stability fixes). I couldn't download it on TIS2Web, but GM is moving to a new system called "techconnect" that costs like ~$3,800 a year (I'll pay $40 for 2 years of updates, but **** if i'm going to pay $3,800 as a DIYer)

My appointment is on the 11th, but our local EV certified dealership is always backed up.
Thanks! I'll have to check that out. I still have 34.7.1. I was happy that I got in so quick and it went so smoothly. It's a good size city with multiple dealers but not very many Bolts, yet

I think the infotainment downloads can be done via OTA or maybe WiFi. I don't recall exactly what I heard.

I have had a few flaky issues but I don't stress it a lot. lol I did have an issue where the cruise control quit working until I cycled the car off/on. I don't suppose that's infotainment though.
 

·
Registered
Joined
·
85 Posts
I got my 2019 updated yesterday (4/30/2021). It did take awhile. The update time is listed at 1.1 hours. With this plus the Multipoint Inspection that they always do I was at the dealership about 2 hours. Adjust your expectations accordingly. BTW, I do think that all of this effort is of value and I would be dubious of relying on an over the air update.

I have not noticed any issues so far. I can set the charge target to 100% so that looks good. Given my normal usage pattern, I will continue to charge to less than 90% unless I will need more. Normally I only charge to 60% using departure charging. FWIW
Is hilltop back in settings or do the 2019's have the set charge level in settings?
 

·
Registered
Joined
·
8 Posts
The fix will be to modify the Bolt's operating system's software to watch for a particular irregularity, which they have determined might indicate the potential for a fire. I suppose when that irregularity is noticed the car will shut down and notify Chevrolet through the Bolt's OnStar service. One would hope this doesn't occur hundreds of miles from home at some remote charging station. Will Chevrolet come to our rescue and provide us with a car while they change the suspected battery?

I had planned on keeping my Bolt 10 or 20 years as I have every other new car I have ever purchased. Will this "fix" the last that long? Will it cause any other problems? If it does will Chevrolet "fix" my Bolt again? I didn't spend $40,000 to help Chevrolet develop the electric car. If they or their subcontractor made a mistake they need to stand up and fix it. The world is way too connected today to try to slide by with a patch. It's about reputation and future business.
 

·
Registered
Joined
·
5,043 Posts
I just think that if the software detects an issue on an out-of-warranty battery, that GM should be on the hook for it. Having multiple vehicles go through major recalls and lawsuit settlements, I can almost guarantee that GM will agree to extend the warranty on the packs. The only question is if they only cover the major faults, or if they extend coverage for battery degradation too.
It's already warrantied for what, 8 years (doesn't CA get 10 by law)? I would be surprised if they extend the warranty further.
 

·
Registered
Joined
·
5,926 Posts
The fix will be to modify the Bolt's operating system's software to watch for a particular irregularity, which they have determined might indicate the potential for a fire.
I wonder if it's a good idea to charge to 100% a few times after receiving this patch on the basis that the "irregularity" may not show up or be detectable unless the battery is topped off and the BMS balances the cells....?
 

·
Registered
Joined
·
8,205 Posts
I wonder if it's a good idea to charge to 100% a few times after receiving this patch on the basis that the "irregularity" may not show up or be detectable unless the battery is topped off and the BMS balances the cells....?
Oh yeah. They say this is the solution. You will never know, if you only charge to hilltop.
 

·
Registered
username LT
Joined
·
565 Posts
I mostly charge at a free-on-weekends, open-lot, public L2 as my apartment building can't be bothered. Maybe for the first few times I'll go to 100% when I have more confidence in reports here to get the "fix" and leave it outside afterwards. See if it ignites.
 

·
Registered
Bolt EV, 2019, Premier
Joined
·
204 Posts
The fix will be to modify the Bolt's operating system's software to watch for a particular irregularity, which they have determined might indicate the potential for a fire. I suppose when that irregularity is noticed the car will shut down and notify Chevrolet through the Bolt's OnStar service. One would hope this doesn't occur hundreds of miles from home at some remote charging station. Will Chevrolet come to our rescue and provide us with a car while they change the suspected battery?

I had planned on keeping my Bolt 10 or 20 years as I have every other new car I have ever purchased. Will this "fix" the last that long? Will it cause any other problems? If it does will Chevrolet "fix" my Bolt again? I didn't spend $40,000 to help Chevrolet develop the electric car. If they or their subcontractor made a mistake they need to stand up and fix it. The world is way too connected today to try to slide by with a patch. It's about reputation and future business.
I imagine that if the condition arises, it will cause the CEL light to come on and a message to be displayed. I don't imagine that they expect an immediate peril to be present. Then again, there might be various warning levels that escalate up to "run like **** and call 911"

I would think that GM has to be pretty convinced that this condition will not escalate into a fire super fast!
 

·
Registered
Joined
·
713 Posts
The fix will be to modify the Bolt's operating system's software to watch for a particular irregularity, which they have determined might indicate the potential for a fire. I suppose when that irregularity is noticed the car will shut down and notify Chevrolet through the Bolt's OnStar service. One would hope this doesn't occur hundreds of miles from home at some remote charging station. Will Chevrolet come to our rescue and provide us with a car while they change the suspected battery?
Has it been announced that it will shut down in the case of fault detection? Seems like another way to do it would be to limit the charge level to a safe level (and passively bleed off excess charge if it is above that level when the fault is detected) so that the car can be driven to the dealer for repair (of course, a warning message would also have to be displayed telling the owner to take it in for repair). After all, if 95% is safe now, bring back the 95% limit if a fault is detected would still be safe, right?
 

·
Registered
Joined
·
8 Posts
I wonder if it's a good idea to charge to 100% a few times after receiving this patch on the basis that the "irregularity" may not show up or be detectable unless the battery is topped off and the BMS balances the cells....?
I suppose someone who travels a lot will have to be the guinea pig?
 
81 - 100 of 139 Posts
Top