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Discussion Starter · #1 ·
I'm using delayed charging with a departure time set to 8am (stock EVSE, setting at 8A). Yesterday I got home at 5:15pm having consumed only 4.5kWh from that morning's full charge. After plugging in, it started charging immediately and said that charging would complete at 7:45pm the following night!!! (a full 26.5 hours later)

I checked the OnStar App after a few hours and now it said that charging would complete at 11:30pm that same night, which seemed much more reasonable. But why was the original estimate off by so much (it has been awfully cold here)? It makes delayed charging kind of pointless, since it starts charging right away and then finishes hours early.
 

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Which type of delayed charging are you using? The modes that consider off-peak rates can cause strange outcomes like that depending on how you have it set up.
 

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Discussion Starter · #3 ·
Which type of delayed charging are you using? The modes that consider off-peak rates can cause strange outcomes like that depending on how you have it set up.
Oops, forgot to mention that... It's the basic version based on departure time only.
 

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Just my two cents here, but if only charging at 8 amps on a 120v line, it means you're using around 900 watts to send to the car (I know the math says higher, but let's assume line losses and normal variances for things like resistance, lengths of cords, etc). So. 900 watts.

How cold is it where you are? How cold has it been overnight? It may say that it would be a LOOOOONG time to charge, but it's just a guess, and it's basing that guess on the temperature and conditions it's been driven in.

Some of that power has to go to maintaining the batteries while being charged and/or stored overnight, running heaters and pumps. That leaves very little else for the actual charging portion that reaches the battery.

I have a Level II charger in my garage which is not connected to the house (think: oversized shed, no insulation). On a nice Spring day, I'm charged up in 4.5 hours or less from dead. When it's way below freezing, that can go up to 6 hours, even though I have 3600 watts at my disposal.

So the limiting factor here is the 8 amp charging and the cold, but that's just my guess.
 

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Discussion Starter · #5 ·
Thanks for the response. It was actually pretty warm at 30F yesterday, but over the weekend the lows were in the single digits with highs in the teens. The garage is semi-detached, so does not reach temperatures much higher than outdoors.

The strange part is that the actual charge only took about 6 or 7 hours. It was just the initial estimate that was really high. As the car began charging, that estimate dropped quickly. However, the decision of when to begin delayed charging is based on this initial estimate, so it would be nice if it was more accurate.

I'm not sure if the colder weekend temperatures (and slower charging) were somehow averaged into the estimated charge time.
 

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I've just noticed my Volt overestimating the charge completion time by several hours in the last couple of weeks, without any change in temperature. Did your estimate go back to normal or are you still seeing it way off?
 

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Discussion Starter · #7 ·
I've just noticed my Volt overestimating the charge completion time by several hours in the last couple of weeks, without any change in temperature. Did your estimate go back to normal or are you still seeing it way off?
Still way off... The initial charge estimates are now about 6 hours per kWh at 8A and 4 hours at 12A. I'll probably head to the dealer and have all outstanding recalls/campaigns performed.
 

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Mine is doing the same. I'm at 12amp mode and it does finish charging by the time I expect it to (7am) but the estimate is many many hours later. Quite irritating....
 

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I'll be taking mine in for this issue on Wednesday. If they fix it or pass any information I'll relay it here.

Edit: They sent my charging history to GM and will let me know what they come back with. They asked to see my charger, but I had left it at home.
 

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Mine is doing the same. I'm at 12amp mode and it does finish charging by the time I expect it to (7am) but the estimate is many many hours later. Quite irritating....
Last night I came home with barely two miles on guess o meter, so basically on Empty. The time to charge completion was 27 or 28 hours, which is about DOUBLE what the normal 12amp full charge should take. That seems to jive with other seat of the pants calculations I did when the battery was only partially depleted. Regardless, the battery was fully charged by my morning, in half the time being estimated. Strange...
 

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Discussion Starter · #11 ·
I went to the dealer on Friday and had the recalls/campaigns done (16055 and 17058). Charging estimates have been back to normal all weekend. Not sure if the service updates actually fixed the issue or if some module just needed a reset which was part of the procedure. Clearly some state was reset as I had to change my charge settings back from the defaults.
 

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I went to the dealer on Friday and had the recalls/campaigns done (16055 and 17058). Charging estimates have been back to normal all weekend. Not sure if the service updates actually fixed the issue or if some module just needed a reset which was part of the procedure. Clearly some state was reset as I had to change my charge settings back from the defaults.
My 2017 has been doing this for most of the time I've owned it. The charge complete time is useless, as is rate-based charging, since the car always thinks it has to charge right now, regardless of rates. (I have to fudge the rate/time settings, to get a full charge while minimizing peak rate charging.)

I've also had a couple software updates in this time. After the updates, charge complete time works perfectly for a week or more, then slowly starts increasing the estimated charge complete time. Honestly, I have no idea how many hours it thinks it will take, since it only states a completion time, not a completion date...

For the record: 12A charger, roughly 12 hour charge time (full charge daily). I occasionally (not often) get home late night and don't have time for a full charge, so I get a partial charge. I've wondered if that's hosing the charge complete calculation, since the partial charge doesn't reset the kWh used.
 

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I went to the dealer on Friday and had the recalls/campaigns done (16055 and 17058). Charging estimates have been back to normal all weekend. Not sure if the service updates actually fixed the issue or if some module just needed a reset which was part of the procedure. Clearly some state was reset as I had to change my charge settings back from the defaults.
I just had the same 16055 & 17058 updates done and now my charging estimates look correct again. I hope it sticks....
 

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That's didn't last..... the estimated time of charging completion is way off again, like roughly twice the time it actually takes. Frustrating. I guess it's back to the dealers again.
 

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I'm curious. If you don't get any benefit from lower rates at night, why not plug it in when you get home and leave it there? My understanding is that the car will stop charging when necessary, and the battery is happier in the morning if it's still plugged in just in case it needs to keep warm, or cool off. Is that not correct?
 

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JRRF, I agree - in that case (and in general), you should plug in whenever you're at home. The issue in my case is that I DO get lower rates at night. However, when I get home, the car thinks it won't be done charging by the time I leave in the morning, so it starts charging immediately, without waiting for the night rate hours I've programmed into it.
 

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Have you queried the odb bus to see what your power consumption is? Or use an evse that let's you monitor power consumption. You may have bad wires and are getting throttled due to inconsistent power in.


Sent from my iPhone using Tapatalk
 

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I've used a kill-a-watt on the line in, which shows 12A at 124V. Further, the car charges consistently in about 12+ hours. So actual charge rate is not affected - just the car's estimate as to how long it will take.
 

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The problem with these types of issues is that you need a software engineer to figure it out. If the dealer only has mechanics who've taken a class on the car, they may never be able to resolve it.
 

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I'm curious. If you don't get any benefit from lower rates at night, why not plug it in when you get home and leave it there? My understanding is that the car will stop charging when necessary, and the battery is happier in the morning if it's still plugged in just in case it needs to keep warm, or cool off. Is that not correct?
Yea just like jtechau described, it starts charging during the peak rates time because it thinks it won't be done if it waits. But if it did wait, it would be done by morning using only off peak rates
 
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