Range restored after battery cell replacement - Chevy Bolt EV Forum
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post #1 of 13 (permalink) Old 05-03-2019, 01:07 PM Thread Starter
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Red face Range restored after battery cell replacement

I'm happy to post that the repair to my 2017 Bolt EV battery appears to have worked.

My dealer's service department installed a new battery cell after they discovered which cell lost power over the winter, and after about 3 weeks the full range capacity has finally recovered. Battery range loss started in a cold February and continued and got worse in March (down to only 40 miles range maximum).

Current range is 277 miles average (better than when the car was brand new). I wonder if this range will continue and if they installed a higher capacity battery cell.
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post #2 of 13 (permalink) Old 05-03-2019, 01:21 PM
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Originally Posted by Alan Spector View Post
I'm happy to post that the repair to my 2017 Bolt EV battery appears to have worked.

My dealer's service department installed a new battery cell after they discovered which cell lost power over the winter, and after about 3 weeks the full range capacity has finally recovered. Battery range loss started in a cold February and continued and got worse in March (down to only 40 miles range maximum).

Current range is 277 miles average (better than when the car was brand new). I wonder if this range will continue and if they installed a higher capacity battery cell.
Great news!

Would love more information. First off, there is no way to replace a single cell in a Bolt. The 288 cells are welded in parallel groups of 3. These groups are then welded in modules of 8 or 10 parallel groups, in series. The modules are assembled 2 per section. The 5 sections are not designed to be taken apart.

They presumably replaced a single section. This would be a new policy. Up until recently they were only replacing entire packs. If this can be verified, it would be news worthy. It would either suggest increased confidence in their dealer technicians, or more likely, a problem with supply from LG.

Last edited by GJETSON; 05-03-2019 at 03:54 PM.
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post #3 of 13 (permalink) Old 05-03-2019, 02:06 PM
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I always assumed they replaced the entire battery pack, refurbished it (or remanufactured) and then sent it back out into the service part pool. It would be nice to know if they actually replaced one of the 5 sections as GJETSON asked above.
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post #4 of 13 (permalink) Old 05-03-2019, 02:35 PM
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Originally Posted by ZoomZoom View Post
I always assumed they replaced the entire battery pack, refurbished it (or remanufactured) and then sent it back out into the service part pool. It would be nice to know if they actually replaced one of the 5 sections as GJETSON asked above.
I can't cite a source, and I could be mistaken, I did a quick google and didn't find a definitive answer, it might be State specific, however I don't think they can use remanufactured components for warranty service. IE if a engine spins a bearing you can't R&R the engine with a "factory refurbished" engine, it must be "New"

So you could replace a module or cell group, if the factory has a process and allows, but not replace the entire battery pack with a refurbished pack. Can anyone confirm or show otherwise?
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post #5 of 13 (permalink) Old 05-04-2019, 07:18 AM
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Originally Posted by wonderbolt View Post
however I don't think they can use remanufactured components for warranty service. IE if a engine spins a bearing you can't R&R the engine with a "factory refurbished" engine, it must be "New"

So you could replace a module or cell group, if the factory has a process and allows, but not replace the entire battery pack with a refurbished pack. Can anyone confirm or show otherwise?
Says who?

Unfortunately, https://www.chevrolet.com/owners/warranty only has the the '18 warranty booklet at https://www.chevrolet.com/content/da...nformation.pdf.

Page 4 says
Quote:
"Needed
repairs will be performed using new,
remanufactured, or
refurbished
parts."
Page 14 says:
Quote:
If warranty repair requires
replacement, the high voltage
battery may be replaced with either
a new or factory refurbished high
voltage battery with an energy
capacity (kWh storage) level at or
within approximately 10% of that of
the original battery at the time of
warranty repair.
Page 16 says:
Quote:
Components
used in exchange are service
replacement parts that may be new,
remanufactured, or refurbished.

Remanufactured parts meet GM
approved service part requirements
and are made from previously used
components in a process that
involves disassembly, inspection,
cleaning, update of software and
replacement of parts as appropriate,
testing and reassembly.

Refurbished parts meet GM
approved service part requirements
and are previously used parts that
are inspected, cleaned, tested, and
repackaged.
Tesla replaces battery packs on S w/refurbished ones all the time.

When we finally got a capacity on Leaf: http://www.mynissanleaf.com/viewtopic.php?f=4&t=13192, they reserved the right to use a "remanufactured" battery.
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post #6 of 13 (permalink) Old 05-04-2019, 08:16 AM
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There you go, right in the manual, thanks for finding that and correcting me.
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post #7 of 13 (permalink) Old 05-04-2019, 11:50 AM Thread Starter
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Battery Part replaced

Thanks for the comments. According to the service department description the REPLACED #4 SECTION IN THERM-MAT

Attached is the info from the service report, including part numbers replaced.

Do you think the new parts increased the range capability of the entire battery? or will it go back down to 238 mi. range eventually?
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post #8 of 13 (permalink) Old 05-04-2019, 11:58 AM
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Originally Posted by Alan Spector View Post
Do you think the new parts increased the range capability of the entire battery? or will it go back down to 238 mi. range eventually?
No. It's very unlikely they used new cells with higher capacity. 288 miles is well within original capacity at less than 50mph in weather like we have now requiring little climate control use.
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post #9 of 13 (permalink) Old 05-04-2019, 06:11 PM
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Alan, thanks for the info!

BTW, your picture has some personal info in there. If I were in your shoes, I'd black or blur those out and post a replacement image w/PII removed.
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post #10 of 13 (permalink) Old 05-04-2019, 06:44 PM
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Originally Posted by Alan Spector View Post
Thanks for the comments. According to the service department description the REPLACED #4 SECTION IN THERM-MAT

Attached is the info from the service report, including part numbers replaced.

Do you think the new parts increased the range capability of the entire battery? or will it go back down to 238 mi. range eventually?
OK. They did replace an entire section, as I thought. Section 4 is the bottom one of two sections stacked under the rear seat. Section 5 sits on top of it, and usually runs warmer, per Torque Pro. Section 4 contains module 4, made up of "cells" 31-40, and module 7, made up of "cells" 59-66.

Making a 3 pouch "cell", a module, or a section of higher capacity would be a complete waste. They are all in series. The entire pack can only deliver the capacity of the weakest cell or cells in series. There is no cost effective way to bypass low cells, or transfer energy from higher to lower cells in a pack. The only solution is very consistent cells. From the data scans I have seen online, the thousands of cells in a Tesla pack are more closely matched than the much larger cells in other manufacturers packs. Seems counter-intuitive, but I suspect the much more automated small cylindrical cell manufacturing systems are easier to control for consistent results.
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