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Does anyone know what factors influence battery charge time (especially at 12 amp)? The only variable I can think of that would make sense is temperature, but that's not as simple as it sounds - there's outside temperature and temperature of the battery, which could vary based on recent use.

The Volt's charge time estimates are usually close, but sometimes off by as much as 1.5 hours. Does the Volt estimate charge time based on past charges, or on current temperature and/or other conditions, or something else? Recently I had to wait in the car for someone, and I had the infotainment screen on the charging info page. In the 10 minutes or so I was waiting, it dropped a whole hour and a half off the 8 amp charge time estimate. Why? Why wouldn't this be the same just after stopping the car vs 10 minutes later?
 

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Does anyone know what factors influence battery charge time (especially at 12 amp)? The only variable I can think of that would make sense is temperature, but that's not as simple as it sounds - there's outside temperature and temperature of the battery, which could vary based on recent use.

The Volt's charge time estimates are usually close, but sometimes off by as much as 1.5 hours. Does the Volt estimate charge time based on past charges, or on current temperature and/or other conditions, or something else? Recently I had to wait in the car for someone, and I had the infotainment screen on the charging info page. In the 10 minutes or so I was waiting, it dropped a whole hour and a half off the 8 amp charge time estimate. Why? Why wouldn't this be the same just after stopping the car vs 10 minutes later?
There are a number of things that can affect it. If the engine has run a lot recently, the coolant will be super hot and the A/C compressor will have to run to cool down the coolant before the battery can charge at its fastest rate. Likewise, if it's super cold outside, the car will have to warm up the coolant a bit using the wall power to keep the battery from becoming too cold during charging. The battery likes to be within 3-4 *F of 70 *F (I think I'm remembering that correctly) or it won't accept or provide power as effectively.

If the voltage is fluctuating (could be anywhere from 105-110 to 130-140 on a "120V" outlet), then the amount of power transferred at 12A will vary (the amperage will always be a constant value).

If there are cells in the battery that are more unbalanced than usual, it has to balance them after charging before actually reporting "fully charged" to keep the battery healthy.
 

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Does anyone know what factors influence battery charge time (especially at 12 amp)? The only variable I can think of that would make sense is temperature, but that's not as simple as it sounds - there's outside temperature and temperature of the battery, which could vary based on recent use.

The Volt's charge time estimates are usually close, but sometimes off by as much as 1.5 hours. Does the Volt estimate charge time based on past charges, or on current temperature and/or other conditions, or something else? Recently I had to wait in the car for someone, and I had the infotainment screen on the charging info page. In the 10 minutes or so I was waiting, it dropped a whole hour and a half off the 8 amp charge time estimate. Why? Why wouldn't this be the same just after stopping the car vs 10 minutes later?
You said you were in the Volt with the infotainment system displaying the Energy screen. Anytime the Volt is powered on, other than just the infotainment system/radio, the Volt will use 500 watts. So basically if your Volt was powered on you extended the time need to complete recharging the battery the same as if you were charging at 8 amps instead of 12 amps.
 

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You said you were in the Volt with the infotainment system displaying the Energy screen. Anytime the Volt is powered on, other than just the infotainment system/radio, the Volt will use 500 watts. So basically if your Volt was powered on you extended the time need to complete recharging the battery the same as if you were charging at 8 amps instead of 12 amps.
It's not always using 500 watts. The display is designed to never display 0.0 kW. If the A/C is off and the only things running are 12V accessories, it's going to be much lower than that.
 

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Discussion Starter #5
There are a number of things that can affect it. If the engine has run a lot recently, the coolant will be super hot and the A/C compressor will have to run to cool down the coolant before the battery can charge at its fastest rate. Likewise, if it's super cold outside, the car will have to warm up the coolant a bit using the wall power to keep the battery from becoming too cold during charging. The battery likes to be within 3-4 *F of 70 *F (I think I'm remembering that correctly) or it won't accept or provide power as effectively.

If the voltage is fluctuating (could be anywhere from 105-110 to 130-140 on a "120V" outlet), then the amount of power transferred at 12A will vary (the amperage will always be a constant value).

If there are cells in the battery that are more unbalanced than usual, it has to balance them after charging before actually reporting "fully charged" to keep the battery healthy.
Thanks for this info. I have no idea how constant the voltage from my outlet is, so that could certainly have something to do with it.

You said you were in the Volt with the infotainment system displaying the Energy screen. Anytime the Volt is powered on, other than just the infotainment system/radio, the Volt will use 500 watts. So basically if your Volt was powered on you extended the time need to complete recharging the battery the same as if you were charging at 8 amps instead of 12 amps.
Except the estimated charge time *descreased* as I was sitting there!

Maybe the Volt was absorbing my positive energy. :)
 

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Thanks for this info. I have no idea how constant the voltage from my outlet is, so that could certainly have something to do with it.



Except the estimated charge time *descreased* as I was sitting there!

Maybe the Volt was absorbing my positive energy. :)
Maybe the initial estimated charge completion time was calculated when the Volt was still powered on and plugged in and then the Volt recalculated the charge completion time after being powered off but with Infotainment - Energy Status screen still being displayed.
 

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Maybe the initial estimated charge completion time was calculated when the Volt was still powered on and plugged in and then the Volt recalculated the charge completion time after being powered off but with Infotainment - Energy Status screen still being displayed.
The estimate will always start high and go down the longer it's plugged in. It's very conservative with the initial estimate so that it's easier to plan around without being surprised by not having a full charge when you expect to.
 

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The estimate will always start high and go down the longer it's plugged in. It's very conservative with the initial estimate so that it's easier to plan around without being surprised by not having a full charge when you expect to.
I have not seen that with my Volt. I charge using Level 2 at home and charging is always completed by the time initially estimated for station charging (+/- maybe 10 minutes) when I check the Energy Information Charging display prior to powering off the Volt.
 

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I have not seen that with my Volt. I charge using Level 2 at home and charging is always completed by the time initially estimated for station charging (+/- maybe 10 minutes) when I check the Energy Information Charging display prior to powering off the Volt.
It's not as much of an issue with Level 2, but it was definitely consistently the case when I used to charge solely on Level 1.
 

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Discussion Starter #10
Maybe the initial estimated charge completion time was calculated when the Volt was still powered on and plugged in and then the Volt recalculated the charge completion time after being powered off but with Infotainment - Energy Status screen still being displayed.
The Volt was unplugged the whole time. I pulled to a stop after a long drive and waited in the car for someone I was traveling with to run an errand. During those 10 minutes or so, the estimated time to finish charging (at 8 amps) dropped by about 1.5 hours.

It's not as much of an issue with Level 2, but it was definitely consistently the case when I used to charge solely on Level 1.
I use L1 charging (12 amps at home) and find the estimates to be fairly consistent, with the few odd exceptions I noted above. I don't think the Volt systematically overestimates charge time.

If you're finding consistent overestimates, you may be running into a problem that I and a few other people have reported: for a while, my Volt insisted that the L1 charge time would be something ridiculously high, as high as 25 hours for a full charge - but often just an hour or two more than you'd expect based on 13 hours for a full charge. (If you search this forum for "inaccurate charge time" you'll find 2 or 3 threads on this.) What finally solved the problem was disconnecting the 12 V battery and reconnecting it. After that, the estimates have been much better. I *think* this is a bug in the software for rate-based charging, as it happened when I was fooling around with getting the Volt to avoid charging during peak times.
 

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With L1 charging, I find the car consistently overestimates charging time by 0.5 - 1.0 hours.

The only time I've seen things like 25 hours needed was when delayed charging was programmed into the car. For instance, if the "no charge" zone was 12 hours, the car might charge for an hour, then not charge for 12 hours, and then complete the charge the next 12 hours.
 

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The estimate will always start high and go down the longer it's plugged in. It's very conservative with the initial estimate so that it's easier to plan around without being surprised by not having a full charge when you expect to.
Unless it is like a Microsoft update and the last minute is there for 20 minutes.
 
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