Energy Used to Keep EV Battery Warm - Data

[E365]

Summary: my Cadillac LYRIQ consumed 10.8kWh (86¢) from my 240v Autel EVSE over exactly 12 hours to keep the battery above 32F with an outside temp down to -17F (-27C). Averaging ~900 watts.

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Cold nights lately so I was curious how much energy the battery heating system in my LYRIQ would consume overnight.

I started at -10F with a heated battery - it had been plugged in and charged to 90% before I started the timer. No significant charging or cabin heating occurred.

Temps got as low as -17F and back up to around -5F at the end of the 12 hours. I couldn’t log the battery temp, but it’s seems the car always tries to heat the battery to just above 32F. It was a bit windy too, with wind chills down to -35F. Not sure how well the battery was protected from that airflow.

Heater cycling on/off.

10.83 kWh consumed. I think the 7:23 elapsed time gets paused when the car stops asking for power. It was exactly 12 hours.

Car Scanner data at the start.

Car Scanner data at the end.

I might try it again with my Blazer EV with the smaller ~85kWh battery vs. this ~102kWh pack.

 

[jghall00]

Summary: my Cadillac LYRIQ consumed 10.8kWh (86¢) from my 240v Autel EVSE over exactly 12 hours to keep the battery above 32F with an outside temp down to -17F (-27C). Averaging ~900 watts.

I might try it again with my Blazer EV with the smaller ~85kWh battery vs. this ~102kWh pack.

Thanks for sharing. That's useful info for owners. I just shared a test I did last winter on my Blazer to see how quickly the pack heats during preconditioning, but I wondered what minimum temp the BMS targets when on L2 since I didn't measure that. Everyone is complaining about range in the cold. I keep having to explain repeatedly that the battery should be heated before departure. GM and other manufacturers have done a terrible job of communicating best practices.

 

[mk378]

If you let it get cold, how much time and energy would it take to warm up to be ready to drive?

 

[jghall00]

If you let it get cold, how much time and energy would it take to warm up to be ready to drive?

It's ready to drive immediately, but it may go into turtle mode, in which acceleration and regen are limited until the battery warms up. Here's a test someone did in below 0 weather. I can't speak to how much energy it takes to warm up sufficiently to eliminate the current (amps) restriction. It would only be an issue for me while traveling overnight and haven't encountered that scenario yet.

 

[RhondaHonda]

Interesting data. My Model Y is garaged and it never gets below freezing in there so I’m assuming no or little energy is used. I think if it is single digits to low teens Fahrenheit and I park at work all day I’ve noticed some battery loss though.

 

[Rand]

Nice data,
I have one question how is using energy to heat the battery saving 3.5kg of CO2?

 

[TnT_M]

Temps got as low as -17F and back up to around -5F at the end of the 12 hours. I couldn’t log the battery temp, but it’s seems the car always tries to heat the battery to just above 32F. It was a bit windy too, with wind chills down to -35F. Not sure how well the battery was protected from that airflow.

Interesting data. Likely exponentially cheaper than running my block heater on my Cummins...

FWIW inanimate objects don't care about windchill. The temperature is what's on the thermometer regardless of wind

 

[JWC86]

Pardon my lack of EV knowledge.

Is this electricity used from being plugged in while outside or is this electricity drawn from the battery in the car?

Can it be one or the other? I assume it can be done using grid power but if it’s done on the car’s battery how much range would this eat up?

 

[John Galt]

Enlightening. Does the software break out the battery energy use and cost for climate like cabin heat and A/C?

 

[jghall00]

Enlightening. Does the software break out the battery energy use and cost for climate like cabin heat and A/C?

Yes, it has an energy flow screen.

 

[Cujet]

That's interesting, and not exactly inexpensive. Over the winter months that could add up to negative savings.

 

[MrkofXcellence]

Interesting data. Likely exponentially cheaper than running my block heater on my Cummins...

FWIW inanimate objects don't care about windchill. The temperature is what's on the thermometer regardless of wind

I was paused by this for a minute also. Would an object shed heat faster (thus requiring more power to maintain warmth) if the wind is blowing?

 

[E365]

I was paused by this for a minute also. Would an object shed heat faster (thus requiring more power to maintain) warmth of the wind is blowing?

That’s what I was getting at with that. It won’t get below the -17F ambient temp, but it should cool faster with wind blowing on it, thus requiring more energy vs no wind. (I’d assume).

 

[E365]

Pardon my lack of EV knowledge.

Is this electricity used from being plugged in while outside or is this electricity drawn from the battery in the car?

Can it be one or the other? I assume it can be done using grid power but if it’s done on the car’s battery how much range would this eat up?

This was from grid power in this case. The battery can also heat itself to prep for DC Fast charging. I’ve found it usually heats to around 70F and can take around 45 minutes when it’s close to 0F outside.

 

[jghall00]

I was paused by this for a minute also. Would an object shed heat faster (thus requiring more power to maintain warmth) if the wind is blowing?

Yes, that's literally how the battery is cooled and heated, except liquid is used.

 

[BobsArmory]

Was the car in a garage or outside?

 

[E365]

Was the car in a garage or outside?

Outside

 

[BobsArmory]

I remember a couple years ago people in Chicago were stranded in the city because they couldn't take a charge/waiting in line to charge because of the very cold weather. Whats different here? What am I missing?

 

[UncleDave]

I remember a couple years ago people in Chicago were stranded in the city because they couldn't take a charge/waiting in line to charge because of the very cold weather. Whats different here? What am I missing?

This cars were for the most part completely cold soaked and unplugged and left in the cold, some for a week at the airport.

When plugging a completely cold soaked car, you need to warm the battery first before it will take fast charge so people would leave the airport and drive right to the nearest cluster of chargers around the airport where they would be forced to wait longer than usual to get the car charged.

IIRC - The two stations closest to the airport were suffering power failures (along with those neighborhoods) so people were forced to drive farther out that they normally would have to full chargers with people waiting.

What wasn't so well published was that tow companies had to jump start numerous ice cars during that same event and so many were out that ice drivers had to wait hours as well to get jumped.

The OP is basically keeping the battery warm at night and the car ready to go as well as quickly warm the cabin.

 

[E365]

I remember a couple years ago people in Chicago were stranded in the city because they couldn't take a charge/waiting in line to charge because of the very cold weather. Whats different here? What am I missing?

UncleDave covered it pretty well. The batteries will drive the car just fine when fully cold-soaked. -10F, -20F, etc. The big issue is DC Fast charging. The batteries need to generally get in the 70F range to charge at max speed.

In this case, GM (and I’m sure most all EV manufacturers) recommend keeping your car connected to your home charger when the ambient temps are below 32F or above 90F, so the battery conditioning system can keep the battery in this range and “maximize high voltage battery life”, per GM. I was just curious how much energy I was using when doing this on a really cold night.

I just looked up Tesla Model Y and they also state (in bold, large font, and in all capital letters). “The most important way to preserve the high voltage Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it.”