Garage Battery Warmer.. Crazy but works!

[jeffdom1978]

Has anyone tried something like this before? I have been messing around with different ways to "preheat" my battery before driving in the cold. My commute is only 10 miles and once the temps dip into the 20's I almost never get full regen anymore, even after 10 miles. I've noticed that when I have full regen (no orange bars) battery consumption is much much better.

Charging before I leave works to some extent, but I dont charge every night. So I was messing around with this idea..

I used a twin sized electric blanket and I put a mylar space blanket underneath and wrapped the entire thing in waterproof plastic. I used cardboard box underneath to "raise" the blanket off the cement floor, I measured pretty close to the size of the battery under the car. Let me tell you, this works awesome! I still wake up to 4 bars of limited regen but after only a few minutes I have full battery regen again and my average wh/m is back in the low 300's instead of like 500+

I cant imagine this consumes much electricity and probably pays for itself. With that said, why dont they make something designed to heat the battery this way? Like an industrial heating mat or something..

Its not pretty but it works! Haha

 

[SSedan]

Get a HCWC and charge at as high a rate as possible before leaving. That way the heater in the car wmars the battery, I assure you this will be more efficient, the charging itself will build heat too.

 

[ewoodrick]

Here's the best solution for you. Don't worry about it. You are in a garage, temps shouldn't be dropping below maybe 50. You don't need the full range, you mentioned that you don't even need to charge daily.

Just use the brakes when you don't have the regen. It's actually pretty dangerous to get completely reliant on regen, what happens when you have to drive another car?

You have to keep it warmer? Add better insulation to the garage and just add heaters to the garage.

I suspect that the amount of heat that an electric blanket will generate is going to be negligible. You probably won't feel it more than an inch away and it's not enough to keep the huge battery container anywhere near warm.

 

[brkaus]

I’m guessing it uses more energy than you think.

Helpful if you need the range.

Helpful to maintain full regen.

Probably doesn’t save energy.

 

[Ande]

You are keeping a bigger surface warm, not to mention the concrete, so yes, you are wasting more energy than if the battery was heated in the usual way.

 

[Rocky_H]

I cant imagine this consumes much electricity and probably pays for itself.

Now that's funny. You can't cheat physics. It takes WW amount of electricity to make XX amount of heat to warm a YY pound block of metal up by ZZ degrees. The differences are in where you generate that heat and how efficiently you can get it applied to the whole battery pack with the least losses along the way. I assure you that doing it from a heater inside the battery system, where it can circulate that heat directly among the battery cells, is FAR more efficient and will take a lot less energy than trying to create a warm spot in one place outside the battery in your cold garage air, and then trying to get that passively rising through an air gap (low efficiency convection) through the metal shield on the bottom to warm up through the whole battery.

 

[jeffdom1978]

Yea, I probably am wasting more electricity, I have no idea yet, I'll see on my next bill.

From what I've read the battery heater doesnt really kick on until its really cold, like single digits.

 

[Rocky_H]

Yea, I probably am wasting more electricity, I have no idea yet, I'll see on my next bill.

From what I've read the battery heater doesnt really kick on until its really cold, like single digits.

Yeah, that is something else, which is a different purpose. The car really doesn't proactively warm the battery like you are doing, so if you let the car handle itself, it's going to be cold and have high initial energy use and very limited regen when you first start driving. That's winter in an electric car--oh well. But some people are really bothered by that. So if you want to do this for your own "feel good" aspect about how your drive is, have at it. I just didn't want you to have any misconceptions that this is going to save energy--it definitely won't.

 

[Brass Guy]

From my experience, the car's battery heater kicks in when the regen limit is below about 30kW. Preheating the car will also preheat the battery to that extent (30kW of regen). This was implemented some time ago, firmware version 6 or 7.
If it's really cold in the garage, it may take a good half hour or more to get the battery that warm.

The battery heater might only kick in if range mode is off, but this may have changed with newer versions of firmware.

 

[verdee]

Wasn’t there some mention of preconditioning the battery in a future update?

 

[jruiz510]

Wasn’t there some mention of preconditioning the battery in a future update?

I just got my model S in August is this some type of good will for your battery if you preheat it? I've honestly been hopping in my car that out in the driveway overnight without any preheating.

 

[Rocky_H]

I just got my model S in August is this some type of good will for your battery if you preheat it? I've honestly been hopping in my car that out in the driveway overnight without any preheating.

No, this babying and coddling your battery isn't necessary. They could never sell a car if it had to be treated to that kind of micromanaging. What you are doing is fine. This is just people catering to their own psychological comfort levels. They like the feel of regen and feel annoyed or uncomfortable if the feel of the driving of the car changes and isn't the same year round.

 

[SSedan]

When the battery is cold depending on the level of cold it reduces or even eliminated regen.
This causes frustration for some folks, so they want to get the battery warmer and keep more regen. In my experience with this the easiest way to do it is charge at as high a rate as possible. It will warm the battery for the rate set and then the charging itself will lead to some further heating.

If by Fremont you mean Cali you aren't going to be affected, if you mean Fremont WI, you should be seeing this already and I am nearby if you need cold weather coaching.

 

[jeffdom1978]

So turning the cabin heat on also heats the battery? Is this just indirectly? I didnt know that!

 

[Seawind300]

When you turn the cabin heat "on" near or bellow 32*f ( 0*c) the front defroster comes on first followed by the rear defroster icon then the battery warming icon.

Mike

 

[Brass Guy]

The battery heater is independent of the cabin heater. Each can draw up to about 6kW. Both may kick in when you turn on the heat with the app.

 

[dark cloud]

If you really want to know exactly how much energy the blanket (or any appliance) uses get one of these:

https://www.amazon.com/P3-P4400-Ele...8&qid=1543546494&sr=8-3&keywords=energy+meter

 

[jeffdom1978]

When you turn the cabin heat "on" near or bellow 32*f ( 0*c) the front defroster comes on first followed by the rear defroster icon then the battery warming icon.

Mike

Ahh- perfect! Exactly what I didnt know! Thanks!

 

[scottm]

When you turn the cabin heat "on" using the App near or bellow 32*f ( 0*c) the front defroster comes on first followed by the rear defroster icon then the battery warming icon.

Mike

I wanted to clarify your comment - inserted bold text is mine.

Sitting in the car and using HVAC buttons from inside the car doesn't invoke battery heating, whether you are parked or driving. It's only when the car is parked, and you're using the App -> Climate to warm the car up invokes the battery heater demon - which then decides if it's cold enough to bother warming battery. When you're driving, the demon has a mind of its own and will heat battery whenever it feels, regardless of HVAC settings.

And I think there's some relationship with %charge remaining on the battery whether pre-heating will start the battery warmer or not if you're not also plugged in. Like if you're unplugged, you must have >20% charge. If you ARE plugged in, then using the App to pre-warm the car will draw from shore power and the charge remaining doesn't matter.

If my car was sitting there with 20% and plugged in, I'd be start a charging cycle before leaving as well.

Whew! That's a lot of conditions.

 

[mswlogo]

Has anyone tried something like this before? I have been messing around with different ways to "preheat" my battery before driving in the cold. My commute is only 10 miles and once the temps dip into the 20's I almost never get full regen anymore, even after 10 miles. I've noticed that when I have full regen (no orange bars) battery consumption is much much better.

Charging before I leave works to some extent, but I dont charge every night. So I was messing around with this idea..

I used a twin sized electric blanket and I put a mylar space blanket underneath and wrapped the entire thing in waterproof plastic. I used cardboard box underneath to "raise" the blanket off the cement floor, I measured pretty close to the size of the battery under the car. Let me tell you, this works awesome! I still wake up to 4 bars of limited regen but after only a few minutes I have full battery regen again and my average wh/m is back in the low 300's instead of like 500+

I cant imagine this consumes much electricity and probably pays for itself. With that said, why dont they make something designed to heat the battery this way? Like an industrial heating mat or something..

Its not pretty but it works! Haha

I think it's great idea !!!
Electric Blankets take VERY little power, probably like 20 watts.
I have a Model 3 which is different, can the Model S directly turn on the battery heater and nothing else (directly from shore power).
If it can't then your idea might make sense, if can why not just use that?

You said it's working. Can you give more details on that? Are you tracking cost of running you auxiliary heater?

I have an attached insulated garage. The house is well insulted too. My garage is usually about 10F warm than outside, it does NOT stay at 50F like someone suggested.

I also have a short commute, which is a little painful with an EV (you don't want to just blindly plug in every night or you spend a lot $$$ on heating the battery back up for a small charge)