Winter, hilltop reserve, and battery conditioning

[DNAinaGoodWay]

Good points. I’ll try tracking it like that. It reported 2% this morning, at 35F, but I didn’t record how much total energy was used since yesterday’s full charge. And as soon as I started driving it dropped to 1%.

 

[DNAinaGoodWay]

So, since last full charge, used 2% of 25 kWh on conditioning, or .25 kWh, or about a mile worth of range. Seems reasonable.

 

[gpsman]

Keep in mind DRIVING it is the best way to warm up the battery. And that is FREE heat (normally waste heat).

If you do not need full power in the first mile or two of your commute, I see no reason to waste grid power on heating the battery beyond the bare minimum to get you rolling in the morning.

In the Ford gas/electric hybrid I own (NiMH) they did away with the grid powered battery heater after the first iteration of the vehicle. It just wasn’t needed since you had gas as alternate power. They programmed the car to do a few (usually three or four) 25% discharge and recharge cycles (1.6 kWh battery) in the first 10 minutes when cold. This warmed the battery nicely.

I suspect the maximum power tapers down as temperature falls. But starting with 160 kw, if output were cut in half, you wouldn’t even notice 99% of the time.

Battery conditioning comes on much more frequently in summer. Especially while charging at high currents on a hot day.

 

[TimBolt]

Keep in mind DRIVING it is the best way to warm up the battery. And that is FREE heat (normally waste heat).

If you do not need full power in the first mile or two of your commute, I see no reason to waste grid power on heating the battery beyond the bare minimum to get you rolling in the morning.

In the Ford gas/electric hybrid I own (NiMH) they did away with the grid powered battery heater after the first iteration of the vehicle. It just wasn’t needed since you had gas as alternate power. They programmed the car to do a few (usually three or four) 25% discharge and recharge cycles (1.6 kWh battery) in the first 10 minutes when cold. This warmed the battery nicely.

I suspect the maximum power tapers down as temperature falls. But starting with 160 kw, if output were cut in half, you wouldn’t even notice 99% of the time.

Battery conditioning comes on much more frequently in summer. Especially while charging at high currents on a hot day.

There’s no way to control battery warming in cold weather, it’s done automatically as determined by the car’s battery management system. Not sure if GM designed this to provide just the “bare minimum to get you rolling”, but whatever the engineers determined is required cannot be overridden. I wouldn’t consider energy used to condition the battery wasted, and using grid power preserves the Bolt’s battery range, and is recommended by GM as a best practice.

 

[MikeDabrowski2017]

Have been watching the battery temperature conditioning via the juicebox data logging.
Some observations:

The energy used for each warm up cycle is ambient temperature dependant
When it was 30f it took about .8kwh per heater cycle
When in the 20f range I saw as much as 1.37 kwh

The frequency of conditioning cycles is also variable based on temperature but have not had enough just sitting time for the car to get a good 20f frequency of cycles yet

To see the conditioning energy on the circle graph it needs to be over 1% of the energy used ( minimum display resolution)
Have been leaving the car plugged in with hilltop mode on so each morning the circle graph is reset to 0 on all of the three variables.
After charging and getting several conditioning cycles with the car plugged in, I let the car sit for a day and a half unplugged.
I had seen the approx 6 hour heat conditioning on the plugged in graph from the jukebox so
I knew that 4 -5 .8kw cycles should have happened during the unplugged time.
On powering up I saw no conditioning time on the graph or the % until I started driving.
( can't divide by zero ? )
After driving a short distance and running the heat for a short trip the conditioning % of the total kWh used was close to the 6 kWh that I would have used for conditioning when plugged in.
I also looked under the hood with my thermal camera right at the end of one of the cycles.
The heater hose SHOWED around 70f while ambient was at 20f.
Going to be in the teens next few days and I Will repeat the experiment
Photos
http://99mpg.com/blog/finally-i-have-an-electric-car-chevy-bolt/

May take out the back seat so I can get the actual battery case temperature

 

[MikeDabrowski2017]

Lots of cold weather data since last post has confirmed that the conditioning period is a variable that gets more frequent when it gets colder and the energy used per cycle increases in proportion to how cold it was.
After the cold weather for the last couple of weeks my hilltop reserve range had dropped to 125 miles.
A long trip after the 2 days in the high 40s last week brought the predicted range back to 180 miles.
Have been leaving the car plugged into my level 2 evse between trips.
Driving on snow covered roads with stock tires was fine as I've been driving in new England for over 50 years,and have not had any issues.
Last week I stopped at an intersection, and a Subaru Forrester driven by a 24 year old girl slid into my driver side rear and did $1760 damage to the rear body.

Am quite happy with how the car behaves in the snow, but the other less experienced drivers are a major risk that cannot be avoided.

 

[GetOffYourGas]

Last week I stopped at an intersection, and a Subaru Forrester driven by a 24 year old girl slid into my driver side rear and did $1760 damage to the rear body.

It's always the AWD vehicles. People just assume they are invincible and drive like the roads are clear. Around here, you only ever see the AWD vehicles upside down in the ditch.

 

[WetEV]

Last week I stopped at an intersection, and a Subaru Forrester driven by a 24 year old girl slid into my driver side rear and did $1760 damage to the rear body.

It's always the AWD vehicles. People just assume they are invincible and drive like the roads are clear. Around here, you only ever see the AWD vehicles upside down in the ditch.

They forget that they might have four wheel drive, but everyone has two wheel steering and four wheel brakes.