Battery and component insulation to reduce losses in cold weather

[FMinMI]

After reading an interesting article on InsideEVs about battery capacity loss in cold weather, I went to the Recurrent website ( Winter & Cold Weather EV Range Loss in 7,000 Cars ) to get more information. I was surprised to see that my Model S 75D had TERRIBLE cold-weather performance, achieving only 35% of the rated EPA range at 25F, which is a normal high for folks in Michigan during January and February.

This got me to thinking about when I removed the frunk 'container' and saw all the rubber hoses that snaked around under it. It also reminded me of a post where someone in Canada bought and installed a 'sheet' of insulation for the bottom of their battery pack each winter (but now I cannot find it).

Given the fact that I do have battery degradation (now only seeing 227 miles @100%), and that I live in cold climate state, I would like to see if I can do anything to reduce the loss. Has anyone successfully done any insulation on older models?

 

[Big Earl]

35% of rated range doesn’t sound right. Maybe with multiple very short trips where the car cold soaks in between, but certainly not on a long trip.

The biggest range killers are cabin heat, highway speed and preconditioning for supercharging. If you have a glass roof, putting an insulated cover on it will help a lot.

People tend to drive really fast on Michigan highways - often well above the speed limit. Keeping your speed to near the speed limit will help range a lot.

For short around town trips, don’t precondition. Preconditioning heats the battery, which is a waste if you’re just making an in-town run.

 

[ucmndd]

I’ve spent plenty of time driving in the mid-20s in my S75. It’s never been anywhere near as bad as 35% of rated range.

Maybe 65%.

 

[vcor]

The tests are not EPA tests, nor any kind of monitored tests, but just data from some number of cars, where the only variable saved was temperature. So yes, I can see you get 35% of EPA in below-freezing weather where you are heating the car and going on lots of short trips like most owners do.

One of the tricks with a Tesla is you can turn on the heater 10 minutes before you get into the car so you have a nice toasty car. If not plugged in, that will cost you range (going zero miles using energy at 6 kWh or so). I suspect many Tesla owners use this feature (I do when cold), but it makes the numbers look bad. The top chart shows only a 17% range reduction from 70F to 32F which seems a bit more normal.

For long trips in freezing weather, at the speed limit, I'd expect 20% or so less range than normal. You can test it out in your own car, which is the best way to understand your car and range. Not sure I'd waste any effort trying to add insulation, as I doubt it will have much effect.

 

[Lasttoy]

Several facts missing parked inside at night?? Plugged in every night?? PRE conditioned before u leave home?? Heater turned on before u leave office?? Battery pack must be at 65-68 degrees , or it will not perform. All of these affect pack performance.

 

[geraltofrivia]

Several facts missing parked inside at night?? Plugged in every night?? PRE conditioned before u leave home?? Heater turned on before u leave office?? Battery pack must be at 65-68 degrees , or it will not perform. All of these affect pack performance.

How to get the battery to 65-68 degrees? Would leaving car overnight on charger in Cold weather helps? Also if the car is plugged in should preconditioning or heating the car while plugged in before leaving make any difference in range?

 

[FMinMI]

How to get the battery to 65-68 degrees? Would leaving car overnight on charger in Cold weather helps? Also if the car is plugged in should preconditioning or heating the car while plugged in before leaving make any difference in range?

The car will do what is needed to keep the battery pack at a safe temperature whether it is plugged in or not, but keeping it plugged in and setting a Scheduled Departure time will ensure the pack is warm (which I think is around 70F) and not reduce the SOC so you can get the desired range and regen.

 

[Big Earl]

How to get the battery to 65-68 degrees? Would leaving car overnight on charger in Cold weather helps? Also if the car is plugged in should preconditioning or heating the car while plugged in before leaving make any difference in range?

His assertions are not entirely correct. Peak performance and efficiency will be obtained with a warm battery, but the amount of energy required to warm it up negates those improvements. If you're about to embark on a long trip on which you will be Supercharging, you can precondition the battery pack by activating climate control from your Tesla app with the vehicle plugged in. This will improve range on the first leg of the trip by giving the battery a head start in getting warmed up for Supercharging. If you're just driving around town or making a bunch of short trips, there is no real benefit to doing this.

 

[geraltofrivia]

His assertions are not entirely correct. Peak performance and efficiency will be obtained with a warm battery, but the amount of energy required to warm it up negates those improvements. If you're about to embark on a long trip on which you will be Supercharging, you can precondition the battery pack by activating climate control from your Tesla app with the vehicle plugged in. This will improve range on the first leg of the trip by giving the battery a head start in getting warmed up for Supercharging. If you're just driving around town or making a bunch of short trips, there is no real benefit to doing this.

Now this really makes sense and help. Thank you for your explanation

 

[FMinMI]

His assertions are not entirely correct. Peak performance and efficiency will be obtained with a warm battery, but the amount of energy required to warm it up negates those improvements. If you're about to embark on a long trip on which you will be Supercharging, you can precondition the battery pack by activating climate control from your Tesla app with the vehicle plugged in. This will improve range on the first leg of the trip by giving the battery a head start in getting warmed up for Supercharging. If you're just driving around town or making a bunch of short trips, there is no real benefit to doing this.

I think your assertions are also not entirely correct. Leaving the vehicle plugged in and warming the pack before ANY trip, long or short, has benefits in cold climate. Your statement that by warming the battery prior to a long trip it will maximum range to the next supercharger is true. But around town, the benefit is also present - a cold battery will significantly limit any regen, so that energy (and brake pad wear) will be lost each time the vehicle stops, and in a large city, with many stop and go intersections, can be appreciable. Here in Michigan, where we see winter temps from 0F- 25F, I get zero regen if the pack is cold when I would first start out.

Does one recoup all the shore energy 'put into the pack' if you use SCHEDULE for short drives (vs going out cold)? Probably not, but there is the comfort factor of a warm, toasty cabin, consistent braking/deceleration (if you chose to use strong regen) and a battery pack at the desired departure SOC level (with expected range, at least initially). Of course, this again assumes it is done while plugged in, which is what I suugested he should do...

Cheers.

 

[geraltofrivia]

I think your assertions are also not entirely correct. Leaving the vehicle plugged in and warming the pack before ANY trip, long or short, has benefits in cold climate. Your statement that by warming the battery prior to a long trip it will maximum range to the next supercharger is true. But around town, the benefit is also present - a cold battery will significantly limit any regen, so that energy (and brake pad wear) will be lost each time the vehicle stops, and in a large city, with many stop and go intersections, can be appreciable. Here in Michigan, where we see winter temps from 0F- 25F, I get zero regen if the pack is cold when I would first start out.

Does one recoup all the shore energy 'put into the pack' if you use SCHEDULE for short drives (vs going out cold)? Probably not, but there is the comfort factor of a warm, toasty cabin, consistent braking/deceleration (if you chose to use strong regen) and a battery pack at the desired departure SOC level (with expected range, at least initially). Of course, this again assumes it is done while plugged in, which is what I suugested he should do...

Cheers.

I was thinking on the same line, as the regen braking is not available or limited if the battery pack is not warm. I do think there is benefit to warm it up before any trip, not necessarily in warm weather but where temps go down to 0 to less.

 

[Big Earl]

I think your assertions are also not entirely correct. Leaving the vehicle plugged in and warming the pack before ANY trip, long or short, has benefits in cold climate. Your statement that by warming the battery prior to a long trip it will maximum range to the next supercharger is true. But around town, the benefit is also present - a cold battery will significantly limit any regen, so that energy (and brake pad wear) will be lost each time the vehicle stops, and in a large city, with many stop and go intersections, can be appreciable. Here in Michigan, where we see winter temps from 0F- 25F, I get zero regen if the pack is cold when I would first start out.

Does one recoup all the shore energy 'put into the pack' if you use SCHEDULE for short drives (vs going out cold)? Probably not, but there is the comfort factor of a warm, toasty cabin, consistent braking/deceleration (if you chose to use strong regen) and a battery pack at the desired departure SOC level (with expected range, at least initially). Of course, this again assumes it is done while plugged in, which is what I suugested he should do...

Cheers.

Yes, but my point is that it will take more energy to warm up the pack than you'll regain through the efficiency improvements. If you absolutely need the extra range, preheating the pack from shore power for around-town driving will certainly help. If you don't need that range, preheating the pack is a waste of electricity. If you want more regen right away, that's a choice, and preheating will get you some; but again, the additional regen won't make up for the energy put into heating up the pack, so it's a net negative.

I certainly appreciate a warm cabin, and I will precondition long enough to get it up to temperature - about ten minutes. The pack takes much longer to come up to temp. For me, this is a good balance of comfort and efficiency. Everyone has their own priorities, so do whatever works best for you.