[DonC]

I thought I noticed the Volt losing a couple of miles of range after having a software upgrade but wasn't sure. It wasn't much and I thought perhaps the estimator might have been revised. Making things a little more confusing, I put on new tires and that definitely reduced the estimated range.

I also noticed that a couple of other members mentioned that their range decreased slightly after the upgrade.

I think I may have figured out what is happening. Yesterday I was showing someone the OnStar app. They thought it was very cool but I noticed the Volt was only charged to 96%. This was odd since it was just sitting in the garage having been charged overnight. I thought my wife might have unplugged it before it was finished charging but after running through the times ruled this out. I then plugged the Volt in and had it charge immediately, and it charged to 100%, which added a mile to the range. I considered it might be the temps but while it's cool things are hardly cold. Plus the ELR is sitting in the same garage right next to it and it charges to 100%.

I looked again this morning and, sure enough, the Volt is only charged to 96%. That's close enough to 100% that you don't notice it on the DIC, but just enough to change your range estimate by a mile or two. Not sure if this is a feature or a bug but pretty sure it's a bug introduced by a software update. For those thinking your Volt might have lost a bit of range (a smidge not a chunk) you might want to check this out. Also, does anyone know if there is a TSB or something on this? I don't remember off hand what the upgrade was but I'm fairly certain at least part of it was related to forcing the car to shut down if left unattended for some period of time (I put this off since I liked it the way it originally worked).

 

[hellsop]

I thought I noticed the Volt losing a couple of miles of range after having a software upgrade but wasn't sure. It wasn't much and I thought perhaps the estimator might have been revised. Making things a little more confusing, I put on new tires and that definitely reduced the estimated range.

I also noticed that a couple of other members mentioned that their range decreased slightly after the upgrade.

I think I may have figured out what is happening. Yesterday I was showing someone the OnStar app. They thought it was very cool but I noticed the Volt was only charged to 96%. This was odd since it was just sitting in the garage having been charged overnight. I thought my wife might have unplugged it before it was finished charging but after running through the times ruled this out. I then plugged the Volt in and had it charge immediately, and it charged to 100%, which added a mile to the range. I considered it might be the temps but while it's cool things are hardly cold. Plus the ELR is sitting in the same garage right next to it and it charges to 100%.

I looked again this morning and, sure enough, the Volt is only charged to 96%. That's close enough to 100% that you don't notice it on the DIC, but just enough to change your range estimate by a mile or two. Not sure if this is a feature or a bug but pretty sure it's a bug introduced by a software update. For those thinking your Volt might have lost a bit of range (a smidge not a chunk) you might want to check this out. Also, does anyone know if there is a TSB or something on this? I don't remember off hand what the upgrade was but I'm fairly certain at least part of it was related to forcing the car to shut down if left unattended for some period of time (I put this off since I liked it the way it originally worked).

Any peak restrictions on your charging?

 

[Neromanceres]

I remember there was some issues with some Volt's giving fairly in-accurate range numbers. If I recall it had something to do with an SOC calibration with cars that only travelled short distances between charges. The remedy was to run the battery down to when the gas engine would come on and fully charge and do that a few times to reset everything.

I wonder if this is something similar?

 

[DonC]

The reason I'm looking at the software upgrade is: (1) I noticed the drop in range right after the upgrade for the automatic shutoff was applied; and (2) other members have reported the same thing. Here is an example of from just a few days ago by Prohidium: "I have a 2013 volt which is getting lower miles than it used to. It seems to have changed about the time the last recall was done which is for the vehicle left on - auto shutoff safety issue. I am seeing lots of 9.3 to 9.6 total kwh used when I used to always get 10.2 to 10.6."

Any peak restrictions on your charging?

You mean from the electrical utility? Not that I'm aware of. I have two charging stations in the garage on separate circuits. No issues with the ELR. I'm switching the cars around to see if the issue involves the EVSE but I doubt this is part of the problem.

I remember there was some issues with some Volt's giving fairly in-accurate range numbers. If I recall it had something to do with an SOC calibration with cars that only travelled short distances between charges. The remedy was to run the battery down to when the gas engine would come on and fully charge and do that a few times to reset everything.

I wonder if this is something similar?

Good memory. No, that was when the range degraded but the car charged to 100%. It was reported on in some detail by flmark. Plus the range change was significant. Here it's subtle and definitely something different. As mentioned above, I think it's related to the software update because a couple of members have reported a slight range degradation after having the "upgrade" applied.

 

[WopOnTour]

Hmm. Not heard anything about this. What module was updated? HPCM2? Well that will reset numerous "soft stops" and statistical baselines stored within the module. it may take some time and a few complete discharges- and recharge cycles to reestablish them.
Can't say that I've ever noticed this gage issue though.
WOT

 

[mpmoore1979]

What year is your Volt and can you tell me what the date was when you had the car reprogrammed? There is a bulletin for 2013 Volts that were programmed within dates of Feb 1 2015 through Oct 12, 2015.

 

[canehdian]

I would say 96% is too close to full to be the same issue people were having before.
They were a good 10-15% down from normal.

My guess is it was hot when you returned to charge and cooled off significantly through the night?
What it thought was 100% when hot then became 96% when it recalculated while cold?
I noticed this a lot during the summer, though not typically to as large a drop - maybe 1-2% raw SOC down from full.
This could be exaggerated based on WOTs comments - the computer doesn't have much of a baseline to go on, so SOC estimates aren't as accurate.

 

[DonC]

Hmm. Not heard anything about this. What module was updated? HPCM2? Well that will reset numerous "soft stops" and statistical baselines stored within the module. it may take some time and a few complete discharges- and recharge cycles to reestablish them.

I don't know exactly what module it was. I believe it was the upgrade which contained the auto shut off. The upgrade was done in April. I initially thought it was just the initial baselines but it's been a while and these haven't changed.

I can think of two things which might be involved. One is the EVSE which I've mentioned. The other is I'm using delayed charging. That could potentially be involved. When I replugged the car in to test whether it simply wouldn't charge to 100%, it charged fully without any issue. So a different result when using immediate charging than when using delayed charging. I'm going to use immediate charging with the other EVSE tonight and see what happens.

The change in the SOC charge would be very easy to miss. Since it's almost charged to 100% you don't see anything that suggests an issue on the DIC, and the range drop is not so significant that you start looking energetically. Had I not been showing the OnStar app I doubt I would have ever noticed. Pretty interesting.

What year is your Volt and can you tell me what the date was when you had the car reprogrammed? There is a bulletin for 2013 Volts that were programmed within dates of Feb 1 2015 through Oct 12, 2015.

It's a 2011 MY and the upgrade was applied in April of this year.

 

[DonC]

I would say 96% is too close to full to be the same issue people were having before.
They were a good 10-15% down from normal.

My guess is it was hot when you returned to charge and cooled off significantly through the night?
What it thought was 100% when hot then became 96% when it recalculated while cold?

Agree it's not the calibration issue that you can get from not fully discharging. But I also don't think it's temperature related. Three reasons. One is that the temperature differential isn't all the great (ambient drop outside the garage is maybe 10F at most and inside it's less than that, especially with charging heating things up slightly). Two is that the ELR is sitting right next to the Volt and isn't exhibiting the issue. Three is that it didn't happen before the software update.

 

[mpmoore1979]

Nothing found for a incomplete charge type issue but did find this information.

#PI0614: Battery State of Charge (SOC) Drop After Charge Complete - (Nov 15, 2011)
Subject: Battery State of Charge (SOC) Drop After Charge Complete

Models: 2011-2012 Chevrolet Volt

Some customers may comment on the OnStar® Mylink mobile app or MyVolt.com battery indicator showing fully charged but reporting less than 100% after a complete charge.

The Volt system monitoring and battery conditioning can discharge the battery slightly in order to optimize battery performance and life. As with most batteries, the Volt battery will also self discharge over prolonged periods of time. Battery temperature will also affect the amount of available energy. These factors can produce up a 5% depletion of available energy.

 

[Steverino]

As with most batteries, the Volt battery will also self discharge over prolonged periods of time. Battery temperature will also affect the amount of available energy. These factors can produce up a 5% depletion of available energy.

While plugged in?! That would seem odd, as a small battery level drop caused by preconditioning is made up by the car if it is plugged in.

 

[canehdian]

Self discharge would not be 4% over a couple hours. Maybe 4% over several months.

Agree it's not the calibration issue that you can get from not fully discharging. But I also don't think it's temperature related. Three reasons. One is that the temperature differential isn't all the great (ambient drop outside the garage is maybe 10F at most and inside it's less than that, especially with charging heating things up slightly). Two is that the ELR is sitting right next to the Volt and isn't exhibiting the issue. Three is that it didn't happen before the software update.

I wouldn't rule it out on ambient temp alone - it's battery temp that matters.
If you were using it hard and ambient is reasonably warm, battery will likely be hotter than ambient while parking (made hotter by charging, too, assuming warm but not warm enough to trigger AC cooling).
After it settles to ambient, it could be a bit lower by SOC testing.
2 - if you didn't drive the ELR the same way, it wouldn't arrive in the same temp condition
and 3 - mentioned above - SOC estimation may not be as accurate while it is relearning baselines. (what I describe is typically 2% or so drop, not 4%)
You also said you had never noticed it before - maybe ELR has done it and you just didn't check the exact % from onstar?

I don't think it explains everything - but it is a possibility.

 

[DonC]

It appears that the issue is related to delayed charging. If the car is set to delayed charging it only charges to 96% and the range comes up a mile or two short of a full charge. If I plug it in and charge immediately, whether with the battery 96% charged after delayed charging is finished, or with the battery starting at a much lower SOC, the battery appears to charge to 100%. Doesn't matter which EVSE I use.

I wouldn't rule it out on ambient temp alone - it's battery temp that matters.
If you were using it hard and ambient is reasonably warm, battery will likely be hotter than ambient while parking (made hotter by charging, too, assuming warm but not warm enough to trigger AC cooling).

Temps is a reasonable explanation but overall doesn't seem to fit what I'm seeing. I do believe the range loss started right after the upgrade. I didn't connect the loss to the car not charging to 100% because it never occurred to me this might be a problem and nothing on the displays alerted me to the possibility. I just assumed it might be battery degradation. Now it might be something other than the upgrade, but since the car charges fully if charging is immediate rather than delayed, the issue appears software rather than hardware based.

On the temps I can't think of a pattern that fits. First there is very little variation in temps even over the course of the year. The high and low in July might be 72F and 62F, and in December 62F and 52F. And from April to December you more or less would pick up the entire range of temps. Plus why would the temps not affect it for five years and then suddenly affect it? Also, if temps were involved I'd expect to see different outcomes as temps varied, but consistently over this entire period what I saw was the Volt losing one or two miles on the estimator compared to the prior five years. Here is an example from this week. it's not typical exactly but reasonably common. The ELR was driven 80 miles and then, later that day, the Volt was driven 10 miles. Both cars sat for 12 hours before they started charging. The ELR charged to 100% and the Volt to 96%. My guess is that both battery temps were at 68F (the temp of the coolant) so neither was hotter or colder than the other.

 

[wordptom]

It appears that the issue is related to delayed charging. If the car is set to delayed charging it only charges to 96% and the range comes up a mile or two short of a full charge. If I plug it in and charge immediately, whether with the battery 96% charged after delayed charging is finished, or with the battery starting at a much lower SOC, the battery appears to charge to 100%. Doesn't matter which EVSE I use.

Three questions come to mind.

When the charge is only 96%, does the driver’s display read "fully charged"?

When the charge is only 96%, has the usage screen meter reset itself (it’s supposed to do that only following a full recharge)?

If not, it would seem the delayed charging terminates the process early for some reason. If so, i.e., if the system charges to 100%, resets the usage screen, and then drops down to 96%, is that drop recorded on the usage display as kWh Used?

 

[canehdian]

Plus why would the temps not affect it for five years and then suddenly affect it?

You said earlier that you would not have noticed if you hadn't opened Onstar to show someone.
Have you regularly checked the exact charge level using onstar during those 5 years? It could very well have been doing this all along - it's not noticeable from the driver's cabin, only if you use onstar or OBD to get the precise number from the computer.
You'd also have to be checking ~2 hours after charge completes for the computer to re-evaluate SOC level (assuming charge completed in the first place), otherwise it just reads the default "full" value, in my experience. It appears to receive a signal from the charger saying "full" and applies a standard value to SOC% based on that. In my case, 83.53%. Slightly higher for 11-12s.
If you check shortly after charge complete it will read that value ("100%"). But when the computer goes through its normal recalculation process, it might be a different number.

The ELR was driven 80 miles and then, later that day, the Volt was driven 10 miles. Both cars sat for 12 hours before they started charging. The ELR charged to 100% and the Volt to 96%. My guess is that both battery temps were at 68F (the temp of the coolant) so neither was hotter or colder than the other.

Then that points to one of two things - battery estimation is off because of wiping historical data, it will get better as it relearns. See earlier comment.
Or, as you suggested, a potential issue with delayed charge not fully completing.

 

[wordptom]

Is your delayed charging configured for TOU rates? If you manually changed your clock recently when Daylight Savings Time ended, did you also update your delayed timing schedule?

 

[DonC]

Well with a couple more nights of testing. I plugged the Volt into the other EVSE and charged immediately. It charged to 100%. Last night I charged using delayed charging on the same EVSE and ... it charged to 100%. I'll have to test the EVSE a bit more.

You said earlier that you would not have noticed if you hadn't opened Onstar to show someone.
Have you regularly checked the exact charge level using onstar during those 5 years?

Thanks for the suggestion. No I have not checked, much less regularly checked, the charge status. When getting into the car in the morning I'd just look at the DIC. If all the green bars showed full I just assumed that was 100%. So if had only charged to less than 100% and all the bars were green I wouldn't have noticed.

However, starting this spring I noticed a drop of a mile or two in estimated range. Since that loss corresponds to a mile or two, I'm putting the two together and concluding that the less than 100% charging started at the same time. The reports by other members that they noticed a drop in range after a software upgrade, which is what I noticed, give me more confidence that there is some linkage, at least between the less than 100% charge and the range loss (if not the software upgrade part).

Not completing a charge is different. From time to time I do look at the miles on the center stack. Had that shown more than 40 miles between charges, which you'd get if you were constantly doing partial charges, I would have noticed. So I'm assuming the car registered a full charge and started a new cycle. But that's just an assumption.

I'm thinking your suggestion that the less than 100% charge being related to the wipe of the historical data is something worth considering. We frequently run the Volt battery flat when we go hiking, but we usually stop hiking in the spring because it gets too hot and we're weenies, and we haven't started up yet for a variety of reasons. That may play a role as well.

Is your delayed charging configured for TOU rates? If you manually changed your clock recently when Daylight Savings Time ended, did you also update your delayed timing schedule?

Good suggestion but I don't use TOU.

 

[supchrgamx]

just thinking outloud
maybe leave it plugged in for 24 hrs , give the batteries a chance to balance