In some other threads we have seen battery estimates being affected by always doing partial charges. It seems that the battery has to hit the lower SOC to 'reset' these estimates.

The extreme difference between 240v vs 120v estimate is strange though

Personally, I don't worry about these details as I do immediate charges @240v. Usually from a fully discharged battery.

 

I do partial charges all the time and the estimated charge time is usually overstated a bit. Variations of charger voltage can throw off the estimate by 15-30 minutes when I do a full charge

 

Interesting. Thanks. I actually let the battery run down to 0% today. Sadly it made no difference. I think this is just a software glitch and was hoping someone else noticed it and could provide a workaround. Tomorrow I'll drive it around the block and plug it back in just to see if a "brief" charge, perhaps, is the answer. After that I'll interrupt the charge after it reaches 50% SOC, wait 10 minutes and then plug it back in. Finally I'll try various reset options from the "Settings" menu.

Then I'll just give up and focus on something more important in life (Naturally I've reported this through my dealer to GM but I'm not guessing they will come through with the answer)

 

Funny, I never even look at my estimated charge completion times. I just plug it in and unplug when I need to go somewhere. Of course black electrical tape on the dash works...

 

Any recent updates from the dealer? I've had somewhat similar problems in my Gen 1, but usually only when certain things were reset on the car and it has to relearn. Definitely make sure that the actual time it is taking remains as expected, however.

 

If you're charging at 120v the charge times can vary based on temperature. It can vary at 240v as well but since the overhead is fixed the temperature impacts the time more when charging at 120v. However, the times you're seeing are outside any reasonable estimate. Does it matter if you charge at 8 or 12 amps?

 

Don, the estimate is about 5 hours longer at 8 amps vs. 12 amps. The estimate drops throughout the charge cycle interestingly. Eventually the system "learns" that it will actually make the targeted departure time (at about 75% SOC from a dead battery). It then goes into delayed charging and "wakes up" to top of the battery in time for it to be full at departure time. Really odd.

 

Amber... Thanks so much for the offer. I've tried everything myself that I could think of and will be bringing the car to the dealership this coming Thursday. I'll update the list if I get any news (good or bad). I'm now beginning to wonder if there isn't an issue with the EVSE that came with the car. To be fair, this is more of a nuisance than a major fault but I'd love to get to the bottom of it.

/Andy

 

Ok. Back from the dealer. They would now like to keep the car for the day and work directly with GM with the car hooked up to the diagnostic computer. It sounded like there were a number of different things that could be examined and adjusted but they always did that work in direct consultation with GM engineers. Report back when I know more.

 

Ok. So dealer had car for a full day and applied "Service Campaigns" 43940, 38240 and 27660. Unfortunately this didn't address the charge issue. For example, today my car at 23% SOC claimed a required 18.5 hours to a full charge at 12A / 120V. In fact it will take about 7-8 hours so off by more than a factor of 2. While I don't regard this issue as a show stopper, I am a bit worried that I still have an undiagnosed issue that will eventually become a more serious problem (no proof, obviously). The dealer was very professional but the issue remains. Realistically I am a few days away from having my 240V EVSE up and running and the problem seems to only appear with 120V charging.

I will try two things in the near future and report back. 1) Put the car in "transport mode", wait 15 minutes and then take it out of "transport mode". 2) Perform a full reset of the system from the menu.

If neither of these address the issue, I *may* choose to disconnect the 12V battery, wait and then reconnect it.

I'll report back if any of these produce a remedy.

 

I'm bumping this thread (apologies if this is tedious) just to see if there is anyone who has experienced the anomaly I have. No remedy thus far from myself of GM has addressed the issue. Perhaps this is just not very important to others but I'd be delighted if someone could at least raise their hand and indicate (assuming it's true) that they too have seen this issue.

Example: Tonight my Volt arrived home with 31% SOC. By experience it will take 8-9 hours to get a full charge. I have the morning depart time set to 8:00am. The Volt believes that at 12A 120V, the car will take 19 hours to charge. As such, it starts immediately rather than waiting until around midnight. Meanwhile the 240V estimate appears much more accurate. I am I the only person in the world who has seen this issue? (2016 Volt LT)

 

I've noticed this behavior on my 2017 Volt LT also. It seems to greatly overestimate the 120V charging time.

 

Thank you! This is the first indication that I'm not losing my mind!

 

Made a point to check the estimates last night and this morning. I have my Volt set to charge at 12A from the 120V EVSE.

Last night with only 5km range left the estimate was for 23.5 hours charging time. When I left for work 9.5 hours after plugging in, the car was between 80 and 90% as expected. The charge estimate at that time, to top up the last 10-20% was 11 hours.

I've been ignoring the 120V estimates because they are basically useless.

 

Ok. Thanks for the information. Sounds like I'm not the only one with this issue. I think I'm going to just leave this one alone for now and live with it as a glitch... Just glad I'm not going crazy (yet)!