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New to the forum, first post. I have a 2017 Volt bought new Jan 2017. The estimated time to charge has always been fairly accurate until about 2 days ago when it began giving estimated charge completion times that were way longer than expected. I charge at 120V either at 8 amps or 12 amps. At 12 amps it takes about 12 hours to fully charge. Today with the battery fully depleted it estimated that it would take 18 hours to fully charge. I’m not sure what is happening but it appears either the clock is off, the car thinks I’m charging at 8 amps, or a software constant has become corrupted (all guesses).

I did a search on this issue and it appears that other Volt owners have experienced this, but I was unable to find anyone who resolved the issue with any satisfaction.

I assume GM knows about this. Has anyone resolved this issue?
 

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2016 Volt Premier, delivered Oct/15
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I have mine set to charge by 6 am and if the battery is only 20-30% discharged it gives me a very accurate time close to the 6 am setting. If the battery is more than 60% depleted, it gives me really stupid time estaimates, up to double what it should be. If I recheck the time estimates the finish time becomes earlier and earlier.

One occasion I remember it saying 2 pm, but car actually ended up finishing at 6 am. I charge at 120V, 12 A
 

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When charging at 120 volts, the car will always default to 8 amp charging unless Location Based Charging is activated and the car thinks it’s at its "home" location and the home location is configured for 12 amp charging. Location based charging expires and needs to be reconfirmed every so often (every 90 days), and sometimes the GPS gets "iffy" on confirming the vehicle is at home (e.g., "home" was set with the car parked in the garage facing forward, and it doesn’t recognize it today because the car is backed into the garage).

Perhaps this might indicate what could be happening with your Volt...
 

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There have been scattered reports of this over the last few years. I started what ended up being a very long thread on the topic, which unfortunately got deleted when the forum was moved to new servers. The bottom line is that I have the problem with my '16, and when I tried to get GM to fix it (via two dealers and the online customer service team), they were completely unhelpful: the dealers simply asserted that there is no problem with the car despite clear-as-day evidence to the contrary, and the online team asked a bunch of questions but eventually said they couldn't help.

EddieD, I assum you have set the car to charge according to a rate schedule, or to finish charging at a certain time? I did not notice the problem when the car is set to charge immediately when plugged in. It only became apparent when I tried to use rate-based charging to maximize charging from midnight to 8 am (which is costs less for me). After months of testing out various ideas, here's what I've concluded:

1. The charge time estimate can be reset to the original value (12.5 hours for a full charge at 12 amps) by disconnecting the 12V battery and reconnecting it.

2. After you do #1, the charge time estimate gradually increases over the next few days to weeks.

3. There are also sudden changes in charge time estimate, always making it longer (sometimes absurdly long). In my experience, these sometimes happen at the same time that the car "forgets" the Home location used for location-based 12 amp charging. (Resetting the Home location is supposed to happen every 90 days, but that isn't what I mean: my car occasionally "forgets" its Home location sooner than 90 days, and without the usual pop-up warning on the infotainment screen. A big increase in charge time estimate sometimes accompanies this event.)

4. I am not certain, but I *think* having the clock set to automatically sync to the cell phone signal increases the occurrence of these sudden large increases in charge time estimate.

5. I am somewhat more certain that using location-based charging increases the occurrence of the sudden large increases.

6. What I've done most recently (in August) is (a) set the clock to not sync automatically, and (b) turn off location-based charging, and (c) disconnect/reconnect the 12V battery. I manually set the car to charge at 12 amps when I arrive at home. I use rate-based charging to maximize charging between midnight and when I leave for work at about 7:30 am. After 12 V battery disconnect/reconnect, the charge time gradually increased to about 14.5 hours per full charge. It seems that it has stabilized there for the last month, without any sudden increases. By setting the off-peak rate period to end at 9:00 am, and departure time at 9:00 am, the car pretty reliably finishes charging between 7:00 and 7:30 am.

My suggestion for anyone having this problem is to do what I did in #6, and report here whether it worked. You might have to substitute different departure times based on your car's own charge time estimate. You can use some simple algebra to figure out what it should be (which I'd be happy to post here if anyone is interested).
 
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