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Discussion Starter #1 (Edited)
Late yesterday afternoon I plugged my Bolt in (L2), and a few hours later I received the notification the charge was complete. Too lazy to go out and unplug it, I left it plugged in overnight (outdoors). Looking at the charging data this morning, I saw the car pulled about .5 kWh over 9 minutes around 8:30 AM, corresponding to a dip below freezing in the outdoor temperature. Is this the battery heater kicking in?
 

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Yes. It's better for efficiency if the battery is around 65F. Leaving the car plugged in will accomplish this, using power from the charger as opposed to battery power. The heater will come on at some (really cold?) point even if the car is not plugged in, but it will use battery power for that.
If it's cold outside, it's best to leave the car plugged in but set the max charge level to around 80-90% (avoid 100% unless you really need the charge).
 

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Discussion Starter #3
Thanks. I knew it did this, but I wasn't sure if that is what it looked like. I set the max charge at 90% the day I brought it home, but I may go down to 80% now that it's only used locally.
 

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The battery heater only takes 2kW. It must be doing more than just warming the battery. Can't imagine what else the car was doing though. Perhaps the soc dropped because of the temperature dip, so the battery got charged some.

-TL

Sent from my SM-N960U using Tapatalk
 

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The battery heater only takes 2kW. It must be doing more than just warming the battery. Can't imagine what else the car was doing though. Perhaps the soc dropped because of the temperature dip, so the battery got charged some.

-TL

Sent from my SM-N960U using Tapatalk
He said .5 KW (0.5 KW), not 5 KW...

Keith
 

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The battery heater only takes 2kW. It must be doing more than just warming the battery. Can't imagine what else the car was doing though. Perhaps the soc dropped because of the temperature dip, so the battery got charged some.
I am not sure why you concluded this. The battery heater does operate at 2000 watts. Being on for ~ 15 minutes would use ~ 0.5 kWh. I am sure that rounding means that ~ 9 minutes would "spend" that amount. Were you considering that 0.2 kWh went to battery charging? You may be right, but I think the number of "significant figures" in 9 and 0.5 allows for rounding to be the explanation.
 

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My bad. The dot in .5 kw didn't show up on the same line as the 5, so I thought it was 5kw.

-TL

Sent from my SM-N960U using Tapatalk
 

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Despite this being a valid point (battery heater kicked in), I question it WHY it did, if it did.

First thing coming to mind is - what was the battery level before you started charging and what was the ambient temperature.
Sure, I charge down from 10-20% up to 90% whenever needed. I do not plug it in each time. However, after the few hour charge session the battery is hot (OK, warm) and I do not anticipate it too cool off this quickly to require extra power to warm it up.
Unless thermal management when plugged in is to kick in the warmers if battery temp drops to 5 degrees.


One good point, what actually happened to me once, was that the battery SOC changed overtime (temperature or saturation or what nots) and the extra 500 W was added,
 

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Discussion Starter #10
Despite this being a valid point (battery heater kicked in), I question it WHY it did, if it did.

First thing coming to mind is - what was the battery level before you started charging and what was the ambient temperature.
Sure, I charge down from 10-20% up to 90% whenever needed. I do not plug it in each time. However, after the few hour charge session the battery is hot (OK, warm) and I do not anticipate it too cool off this quickly to require extra power to warm it up.
Unless thermal management when plugged in is to kick in the warmers if battery temp drops to 5 degrees.


One good point, what actually happened to me once, was that the battery SOC changed overtime (temperature or saturation or what nots) and the extra 500 W was added,
It just happens that A) my JuiceBox creates nice log files and B) I have a personal weather station which also records its data. So... The car was plugged in at 3:37PM at 47 degrees F. The charge was completed at 8:10PM at 40 degrees F (34.26kWH with max charge set at 90%). The following morning, at 8:17AM at 33 degrees, the car pulled .46kWH over 9 minutes. Again at 11:51AM at 40 degrees, the car pulled .4kWh over 4 minutes. I had not previously noticed that final charge. Maybe not the heater?
 

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The following morning, at 8:17AM at 33 degrees, the car pulled .46kWH over 9 minutes. Again at 11:51AM at 40 degrees, the car pulled .4kWh over 4 minutes. I had not previously noticed that final charge. Maybe not the heater?
I do not have weather station, just thermo/hydrometer units (outside, garage, several rooms in the house) with a nice history graph.
I park in the garage, so it is warmer by a few degrees then outside.
I see what you are saying and it happened to me only once so far.
Also, important to note, I schedule charging to be done shortly before my departure time. Only a few times I started charging immediately.
I use ChargePoint with WiFi, so I get history of charges with graph for each sessions. Cool stuff. lol
Anyway, a few times I noticed that after the charge was done at almost 8 kW, for about a few more minutes current was still flowing, but at much lower rate. Rather like 2.5 kW or so.
In almost all the cases it was lasting for a few minutes, maybe 5-10. Hard to say from this tiny graph. It also has poor resolution and refresh rate.

Once, or twice, back in February, it would stop charging only to a few minutes (less than 5) later start again and this time roughly 2 kWh.

Since it was inside, although near floor temp could be 40 F, and the charging session added more than 30 kWh, I doubt the battery got cold enough shortly after the session...
Also, charging up to 90% (does not affect regen) should not be slowing down due to battery getting full. Then, battery would be warm enough after say 5 hours of charging so why keep pumping heat into it?
A tad weird to me.
 

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At the end of a charging session, the BMS will heat or cool the battery as needed to get to the optimum temperature.

Keith
 

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Discussion Starter #14
I do not have weather station, just thermo/hydrometer units (outside, garage, several rooms in the house) with a nice history graph.
I park in the garage, so it is warmer by a few degrees then outside.
I see what you are saying and it happened to me only once so far.
Also, important to note, I schedule charging to be done shortly before my departure time. Only a few times I started charging immediately.
I use ChargePoint with WiFi, so I get history of charges with graph for each sessions. Cool stuff. lol
Anyway, a few times I noticed that after the charge was done at almost 8 kW, for about a few more minutes current was still flowing, but at much lower rate. Rather like 2.5 kW or so.
In almost all the cases it was lasting for a few minutes, maybe 5-10. Hard to say from this tiny graph. It also has poor resolution and refresh rate.

Once, or twice, back in February, it would stop charging only to a few minutes (less than 5) later start again and this time roughly 2 kWh.

Since it was inside, although near floor temp could be 40 F, and the charging session added more than 30 kWh, I doubt the battery got cold enough shortly after the session...
Also, charging up to 90% (does not affect regen) should not be slowing down due to battery getting full. Then, battery would be warm enough after say 5 hours of charging so why keep pumping heat into it?
A tad weird to me.
I have seen no end taper when charging to 90%, but I do when charging to 100%. My graphs do however, show a very tiny taper from start to finish in both cases. I lose full regen until I get down to somewhere around 87%. FWIW, my station is a JuiceBox NexGen 32.
 

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I have seen no end taper when charging to 90%, but I do when charging to 100%. My graphs do however, show a very tiny taper from start to finish in both cases. I lose full regen until I get down to somewhere around 87%. FWIW, my station is a JuiceBox NexGen 32.
What year is your Bolt? In my 2017 I get full regen at 95% and lower (after driving 10 to 15 miles on a full charge depending on how aggressive I am driving). If I only charge to hill top reserve I always have full regen.

Keith
 

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I have seen no end taper when charging to 90%, but I do when charging to 100%. My graphs do however, show a very tiny taper from start to finish in both cases. I lose full regen until I get down to somewhere around 87%. FWIW, my station is a JuiceBox NexGen 32.
Yes, when filling to 100% it is normal to slow down and regen being limited.
I also experience limited regen, but that is only for a few miles (flat terrain). The limitation, though, is minimal, like 15% of the range.
 
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