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2022 LT, Post Battery Recall. High Desert Climate
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Discussion Starter · #1 · (Edited)
Update: @raitchison posted an update of his thermal control observations for Bolts with post recall batteries and updated software in post #10, below. Well worth reading

I'm hoping that thermal control will lead to a long-lived battery pack. Details are hard to come by in the user manual so this thread is meant to consolidate information on the topic. An earlier thread made it pretty clear that it is a good idea to plug in the car at home and not set a charging schedule* so that the most aggressive thermal control program is used by the car. I've been doing that for about a week now, while also monitoring module temperatures via Torque Pro. My summer climate is high desert -- 90F - 100F peaks most days, nadirs of about 70F. Very sunny.

I've seen peak module temperatures of 90F after long daytime commutes with high AC usage. I think the car decides to actively cool the pack down when module temps are something over 90F. The two times when I have checked temps a couple hours after leaving the car parked and plugged in the highest temp module has been ~ 85F, and on multiple readings in the AM the pack is at 75F.

Please add more anecdotal information. Hopefully over time or with input we can describe the summer control rules. My car is a 2022 LT after battery swap -- I don't know if other years/trims have different control strategies.

* This is obviously sub-optimal for people who want to schedule charging. In order to not clutter the thread, please discuss that aspect of charging elsewhere.
 

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For clarification, I believe your question is for Bolts with new batteries and updated software...? The battery conditioninng behavior for Bolts with the recalled battery and no software update was fairly well documented by @raitchison here:

Edit: better post that summarizes his findings
 

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I live in the CA central valley, and this time of year we are constantly ~100F, with lows of ~65-75 depending on the amount of ocean air pulled in at night. I don’t take battery temperature, and the temperature in the garage is ~5 degrees less than outside at the peak high, and will stay warm until the big door is opened to let the heat out.

I have only witnessed the pack run cooling while it is being charged. I have left the car plugged in for a couple days without driving it, but I have yet to see any cooling other than towards the end of a 50%+ increase charging session.

I think my area has the potential to get so hot that BMS cooling could take place without also charging, but I guess that the temperature inside the garage would need to be over 95F for some time. The battery is going to take some time for the ambient temperature to get the battery temp up high enough for the BMS to kick in.

My guess is highs over 110F with 85+ lows. Like AZ. Then leave it plugged.
 

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2022 LT, Post Battery Recall. High Desert Climate
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Discussion Starter · #4 · (Edited)
For clarification, I believe your question is for Bolts with new batteries and updated software
Down the rabbit hole I go ...
I'd like any Bolt owner to be able to use this thread to find thermal control behavior but if I am understanding you, the thermal control rules vary. I have a Bolt that has had the original battery swapped out for one that is thought to not have a fire risk.

How many sub-groups are there, and how do you suggest they be defined ? Is new pack not subject to recall, and/or swapped pack one group, and all other Bolts another group ? Or does thermal control vary by software version ?

Thanks for the link to raitchison's informative post. I take it his information may not apply to my car.
 

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Thanks for the link to raitchison's informative post. I take it his information may not apply to my car.
To be honest, I'm not sure. We know that some post-charging behavior has changed with the software updates (original "final remedy," interim 80% limitation, new battery, or new Bolt), specifically several hours of monitoring with occasional charging of the 12V.

I don't know if it has changed any of the trigger temperatures for battery conditioning from what @raitchison documented. Hopefully, people will see your thread, add their observations, and we can find out for sure.
 

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For what it's worth, here's a log of my battery conditioning for the past two days. No battery charging took place. The car was parked in the hot garage.
Font Screenshot Rectangle Number Parallel
 

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Discussion Starter · #8 ·
Friday:
Charge up to 80% (the downside of showing my wife how to change the charge limit)
Weekend ...
Less driving, but each day 10 - 15 miles.
My wife went to EA for a dry run -- I presume the session was very short

Daily weather: 90F peaks, about 68F nadirs

Sunday 4pm, 5 hours after the Bolt returned home:
All modules 80F, coolant 85F

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Anybody know where the coolant sensor is located ? It seems to track ambient pretty quickly when passive. The one time I was able to monitor the car cooling down the pack, the coolant temp reached 62F. Pretty cool ;)

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No information to report yet that discloses thermal control rules but the pack temperature is averaging below 80F in our high summer. Not shabby. And since our usage lets us set the charge limit to 60% SoC in the summer without inconvenience, I'm feeling pretty good about the prospects for our pack. I've said it before though, and it remains true: I wish I could cool down the pack in the early AM on demand. Starting each summer day with a pack in 60 - ish F range using the chiller at a COP that I guess would be close to 5 would be awesome.
 

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Anybody know where the coolant sensor is located ? It seems to track ambient pretty quickly when passive. The one time I was able to monitor the car cooling down the pack, the coolant temp reached 62F. Pretty cool ;)
I too would love to know where the sensor is located.

What I've noticed is that unless a battery cooling cycle is in progress that this temp is at or slightly above ambient.

I have observed the coolant temp go as low as 11C (~52F) shortly before the end of a cooling cycle. As soon as the cycle ends it indeed begins to rise quickly.

When a battery cooling cycle starts the temp will frequently rise for a short time before dropping, and you can hear the AC condenser fan ramp up in speed as that temp drops below the battery temp. It seems that the car starts the cooling pump at low speed and then increases the flow once the coolant actually starts cooling down.
 

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To be honest, I'm not sure. We know that some post-charging behavior has changed with the software updates (original "final remedy," interim 80% limitation, new battery, or new Bolt), specifically several hours of monitoring with occasional charging of the 12V.

I don't know if it has changed any of the trigger temperatures for battery conditioning from what @raitchison documented. Hopefully, people will see your thread, add their observations, and we can find out for sure.
So my battery was replaced in February so at this point I've had the better part of a summer with the new battery and software.

There do seem to be some changes in behavior with the new battery/software but they are not dramatic.

I am not as sure that (what I call) weak mode cooling is triggered by a battery temp pf ~33C but it's pretty close to that. It does still seem to be cooling the battery to ~31C.

As far as aggressive mode cooling, it definitely still cools to a battery temp of 27C based on the "Batt Temp" PID. Of the 7 additional battery temperature PIDs some of them will be well below 27C and some will be slightly above 27C but when "Batt Temp" hits 27C, even briefly it stops the battery cooling cycle, you can tell this because the "Batt Coolant Temp" measurement will begin to increase immediately and you can hear the condenser fan spin down to a much lower RPM.

One observation I've made is that the new battery & software takes longer to cool the battery from ~31C to 27C than it used to. In the past it was almost unheard of for a battery cooling cycle to take more than 35 minutes to bring the battery down to 27C now it usually takes 35-40 minutes and sometimes as long as 45 minutes. I really don't know if the difference is based on how the new pack is built or how the cooling system operates.

I'm also relatively certain there are no significant improvements to the insulation of the battery pack, it seems to get just as hot as it ever did on a hot day.
 
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