Would you use battery heating if it were available?

[Andyw2100]

A year ago with probably 5.8 firmware temperatures here got down to the teens and my Model S 85 displayed "heating battery" on the speedometer.

My question when I don't readily see an answer for is, "Why do I care?" Yes, regeneration, but I'm not going to regenerate as much as warming the battery consumes. When really cold acceleration was limited as well but not so much that it affected my commute.

Well, one reason to care is wear on the friction brakes. Another might be if you'd like the car to drive approximately the same way every time you drive it. If losing a few miles of range is not an issue at all, and the things I just listed are, why not warm the battery, even when on battery power? If you don't care about these things then don't warm the battery.

 

[jerry33]

There are a couple of issues here. The first is even if you like your cabin toasty and heat soaked, doesn't it get that way a lot quicker than the battery warms up? In other words, if you weren't also charging the battery, and were limited to warming it via preheating, wouldn't you wind up having to overheat the cabin in order to adequately heat the battery?

The way I do it, heat soaking the cabin means I don't run the heater (and the noisy fans) at all during my commute, which is just over 25 miles one way. It really only needs to get the limiter bar to about 30 kW to behave normally, so one or two cycles does it.

Another issue is that while for many of us it may be relatively easy to time the battery charging to complete when we want to start our trip, so that it is warm, for some people that may not be the case. And even for the technically inclined and knowledgeable, there are still times that this method alone won't work.

As an example, let's say you haven't run the battery down much at all, and don't need to charge it much or any, but still would like to preheat the battery. This is a typical situation for me, say, on a weekend. Another situation might be if you want to go out a time that is not in sync with when you'd like to charge, because of night time charging rates.

There's no way that is perfect for everyone. Generally I have the charging finished by about 04:30, and then heat the cabin for two or three cycles (depending upon the weather) and leave around 05:15. On a weekend, if I don't leave till lunchtime, I just heat the cabin. The cabin is usually warmed up enough that the regen limiter is around 30 kW. That's actually plenty for urban driving and if you are in range mode, the battery won't use too much power just warming it the rest of the way. And if you live where it's really cold (Winnipeg or Saskatoon) your garage is likely heated--at least a bit (10 to 18 C or so) which is better than 0 to 5 C parked outside in my area.

If your schedule is irregular, there's not really a lot you can do because in that case you likely won't know far enough in advance to make heating (cabin or battery) last long enough to make a significant difference.

Scheduled end time charging, with Tesla in control, can account for that easily. More importantly, it would make things simple and easy for people who don't want to be bothered thinking about this stuff.

Everyone would like a scheduled end-time charging. I suspect it's harder to do (and get it right every time) in a 60 kWh+ car than in a 25 kWh- car. And yes, when warming the cabin and battery plus charging, the rate of charging goes way down. I generally charge at 33 amps, but that's because of the wonky power in my area.

 

[mknox]

Well, one reason to care is wear on the friction brakes. Another might be if you'd like the car to drive approximately the same way every time you drive it. If losing a few miles of range is not an issue at all, and the things I just listed are, why not warm the battery, even when on battery power? If you don't care about these things then don't warm the battery.

Makes sense. My last (gasoline) car went 4 years and about 75,000 miles on the original brakes, so I am inclined not to worry about relatively infrequent loss or reduction of re-gen and of using my Model S brakes. I figure if my old car can get that kind of life based on my driving habits, then my Model S should do far, far better.

I do, however, like getting in to a warmed up cabin, especially when it's been as cold as it has been. For me, 10 or 15 minutes of pre-heating works great. I will usually have about 30 to 50% of my re-gen to start, but the limits quickly disappear as I drive.

 

[RiverBrick]

A year ago with probably 5.8 firmware temperatures here got down to the teens and my Model S 85 displayed "heating battery" on the speedometer.

My question when I don't readily see an answer for is, "Why do I care?" Yes, regeneration, but I'm not going to regenerate as much as warming the battery consumes. When really cold acceleration was limited as well but not so much that it affected my commute.

Here, it's pretty easy to have motor power limited to as little as 80kW, so it does affect you.

For battery health and longevity, it's better to be driving with a 45°F battery than a 22°F one. Lately, whenever I've visited a mountain for Winter sports, the car has been unplugged and soaked in temperatures around 0°F. For the return home, it would be more gentle on the battery if I could warm it up before use. TM imposes power and regen limits for protection, but it's likely there's some trade-off for practicality. For instance, when power is restricted to 80 kW max, maybe it should be no more than 40 kW, but they allow a bit of extra stress on the battery, because otherwise it would be too crippling.

Yes, preheating the battery when unplugged is going to hurt range, so nobody's suggesting that it be mandatory. However, it should be an option. My electricity is extremely inexpensive and clean and most round-trips where the car is cold-soaked are less than 125 miles, so I would love to be able "waste" energy in order to have a non-frigid pack.


@Andyw2100: I've had the preheat time-out as well. I'm not sure of the criteria for when the heating stops. It's very possible the heat shuts off quicker when the car is unplugged.

 

[David_Cary]

This thread reminds me that we really need a crowd sourced input to Tesla on desired features. Presumably they monitor this forum and can see these things. I know there is a website somewhere but it doesn't get much traffic.

I live in the South but of course I want to preheat my battery sometimes. The crazy thing is that I would want to do this on long trips - ie range mode. The whole concept of range mode not heating the battery when on shore power is just backwards.

And the end timer is not hard. I can't believe a bigger battery makes end timing that hard to calculate. The Leaf gets very confused and sometimes finishes 5 minutes before the end timer and sometimes 1 hour - but it is still better than finishes 5 hours before. The thing that confuses the Leaf the most is slow charging - ie 120V.

An end timer is free battery pre-heating. Come on Tesla!!!

 

[mknox]

TM imposes power and regen limits for protection, but it's likely there's some trade-off for practicality. For instance, when power is restricted to 80 kW max, maybe it should be no more than 40 kW, but they allow a bit of extra stress on the battery, because otherwise it would be too crippling.

I'm not saying that isn't true, but I haven't seen anything to substantiate it. I had heard that batteries operating in the cold were much better than batteries operating hot. It also used to be "common wisdom" that fast DC charging was harmful to batteries, but we seem to have gotten past that with Tesla's Superchargers. Having said that, I too will "go easy" on the car when I see power limits in the cold.

 

[Andyw2100]

This thread reminds me that we really need a crowd sourced input to Tesla on desired features. Presumably they monitor this forum and can see these things. I know there is a website somewhere but it doesn't get much traffic.

Umm...that's pretty much what I'm hoping to accomplish here. If you like the idea, help support it--get people you know to vote, etc. I picked this topic to attempt this with because I thought it should be an easier one, since the battery heating is already happening (just not independently), and because I felt that it was something many people would use, or at least see the need for, and because the recent torque sleep enhancements make it more important to be able to keep the car in range mode, and this would help. If we as a group are successful in getting Tesla's attention with this effort, we can take the same approach for other features in the future. So let's make sure we get as many people as we can behind this one!

Oh, and as for Tesla's monitoring of this forum--while I'm sure they do, I have been in touch with Jerome Guillen on the topic of my letter. I'm planning to let him know about the poll results and this thread once we have a good number of people who have voted.

And the end timer is not hard. I can't believe a bigger battery makes end timing that hard to calculate. The Leaf gets very confused and sometimes finishes 5 minutes before the end timer and sometimes 1 hour - but it is still better than finishes 5 hours before. The thing that confuses the Leaf the most is slow charging - ie 120V.

An end timer is free battery pre-heating. Come on Tesla!!!

I really think with my suggestion to allow users to allow Tesla to vary the amps used during charging in order to more accurately hit the end time estimate, reaching an estimate within a reasonable amount of error should not be difficult. Perhaps Tesla engineers had not considered that option before, or perhaps they thought users would not be open to the idea of setting parameters in that way. Or perhaps they did, and just didn't think it was important enough be worked on yet, choosing to focus on higher priority items. We'll probably never know. But again, with enough people behind this, we might be able to get Tesla to work on these things. They do want to give us, their customers, what we want.

 

[Andyw2100]

@Andyw2100: I've had the preheat time-out as well. I'm not sure of the criteria for when the heating stops. It's very possible the heat shuts off quicker when the car is unplugged.

I'm pretty sure it shuts off after about 15 minutes when preheating from battery power.

 

[jerry33]

I'm pretty sure it shuts off after about 15 minutes when preheating from battery power.

Since 6.1 it shuts off in 15 minutes regardless.

 

[scottm]

Battery preheating while unplugged? Never. Preserve power reserves when there is no access to power.
Preheating while plugged in, sure.

The control for that is already on the app. Here's how:
Plug the car in every night.
Charge to 88% target, now, not timed to start.
Wake up and as you are eating breakfast, use the app to bump up charge to 90% and turn on cabin heat.
With a HPWC in my case, the car is ready in 15 minutes, meaning: finished charge to 90, cabin warm, regen available.
If the battery needed heating it got heated.
I always have regen available doing this, maybe not the fullest regen, but ... good enough.


I dont want to see a button anywhere for warming just the battery.
Life is complicated enough as it is...

 

[Andyw2100]

Battery preheating while unplugged? Never. Preserve power reserves when there is no access to power.
Preheating while plugged in, sure.

This makes no sense.

It's not as if we don't know when we're going to have access to power, so we have to preserve it "just in case."

If we know we have plenty of range to get where we need to get, and want to have regen available at the beginning of the trip, there isn't a reason in the world why we shouldn't be able to warm the battery pack on battery power. If you don't want to, don't. But that doesn't mean Tesla shouldn't give those of us that would like the option to do so that ability. We have the ability now. We just have to remember to toggle range mode on and off, and we also have to heat the cabin along with the battery. So my point is, Tesla already disagrees with you, and has given us the ability to do what you're saying we should never do. Since they've done that, but have implemented it in an inefficient way, wouldn't it be better if they improve upon the implementation?

The control for that is already on the app. Here's how:
Plug the car in every night.
Charge to 88% target, now, not timed to start.
Wake up and as you are eating breakfast, use the app to bump up charge to 90% and turn on cabin heat.
With a HPWC in my case, the car is ready in 15 minutes, meaning: finished charge to 90, cabin warm, regen available.
If the battery needed heating it got heated.
I always have regen available doing this, maybe not the fullest regen, but ... good enough.


I dont want to see a button anywhere for warming just the battery.
Life is complicated enough as it is...

You've completely missed the point about range mode on and off. You have to turn range mode off when you exit the car in order to warm the battery with preheating, and 15 minutes of charging the battery isn't going to warm it much at all in cold weather. In your scenario you're also not allowing for being able to take advantage of lower rates for night charging. Again, if this scenario works for you, great! I have no problem whatsoever with you going this route. But you honestly can't see why the features I've suggested would be helpful to others, even though at this point more than 88% of people here say they would use them?

 

[RiverBrick]

Since 6.1 it [preheating] shuts off in 15 minutes regardless.

I tested it when on shore power and it was still running after 20 minutes when I shut it off manually. Next time, the test will be when unplugged. I have 6.1 build 2.2.115

 

[Matias]

I surely hope heating is on more than 15 minutes. Why an earth would they make such limit?

 

[jerry33]

I tested it when on shore power and it was still running after 20 minutes when I shut it off manually. Next time, the test will be when unplugged. I have 6.1 build 2.2.115

I've timed mine several times and it's 15 minutes exactly. It used to be longer. I'm on .115 too. Perhaps it varies by car. I timed it because I saw a post where Ownership had replied that it stayed on for 15 minutes, and I didn't think it was correct.

- - - Updated - - -

I surely hope heating is on more than 15 minutes. Why an earth would they make such limit?

No idea. I should say that I've never timed it except when it was plugged in.

 

[mknox]

I've timed mine several times and it's 15 minutes exactly.

For some reason, I can't get VisibleTesla to launch in order to check, but I believe I'm on .116. Yesterday at work (and plugged in), my HVAC stayed on for at least 20 minutes... probably more. I know that because I turned it on just after 4:00 pm and it was still running when I went out to the car just after 4:30 pm.

 

[Bratwurst]

Great suggestions and well written. Those of us trying to drive longer range in cold climates really need this.

 

[saladman]

I don't plan on driving my car in severe cold, but having had the LEAF for three years, and being a pilot, I firmly believe In giving the Driver-In-Command the ability to manage all resources to the best of his ability to ensure a positive outcome.

i would gladly pre-heat my batteries at the times and temperatures needed for maximum performance and life of equipment.

 

[Andyw2100]

For some reason, I can't get VisibleTesla to launch in order to check, but I believe I'm on .116.

You should read the VisibleTesla thread for details, but it's possible that the reason you can't get VisibleTesla to launch is that you've been moved to the new servers. Many people, including me, can't use VisibleTesla at all right now because of changes Tesla is making. There are details in the VisibleTesla thread. The following post would be a good place to start if you're not up on what's been going on: VisibleTesla - Page 154

 

[gpetti]

Battery preheating while unplugged? Never. Preserve power reserves when there is no access to power.
Preheating while plugged in, sure.

The control for that is already on the app. Here's how:
Plug the car in every night.
Charge to 88% target, now, not timed to start.
Wake up and as you are eating breakfast, use the app to bump up charge to 90% and turn on cabin heat.
With a HPWC in my case, the car is ready in 15 minutes, meaning: finished charge to 90, cabin warm, regen available.
If the battery needed heating it got heated.
I always have regen available doing this, maybe not the fullest regen, but ... good enough.


I dont want to see a button anywhere for warming just the battery.
Life is complicated enough as it is...

I think you're implying that a battery warming feature might be too complicated but I can't help noting that for many people, your routine might be considered too complicated. I tend to do the "wife litmus test" on these things. To be clear, I'm not trying to suggest anything about my wife's intellect, just that she (like many other people) does not get enjoyment with fiddling around with the car and charge levels and clever timings etc. She would definitely not be interested in messing around with the charge level etc. first thing in the morning.

I think that there are several ways to implement the kind of control that Andy is suggesting without there literally being a button that says pre-warm battery (although that would probably still be more acceptable to my wife). I think the key is that battery warming is explicitly part of any functionality to prepare the car rather than a seemingly accidental side effect of pre-heating the cockpit, that for unknown reasons doesn't work if the range control is on (even when on shore power). The current situation doesn't really make sense and now that more of us will use range mode (to improve P85D range management) we are more likely to end up driving with a cold battery which presumably reduces range anyway and of course reduces regen, making driving characteristics abnormal.

 

[RiverBrick]

I'm not saying that isn't true, but I haven't seen anything to substantiate it. I had heard that batteries operating in the cold were much better than batteries operating hot. It also used to be "common wisdom" that fast DC charging was harmful to batteries, but we seem to have gotten past that with Tesla's Superchargers. Having said that, I too will "go easy" on the car when I see power limits in the cold.

Granted, not all Li-ion chemistries are the same and most likely, this graph isn't based on the Panasonic/Tesla one. However, it does make me want to have the option of warming the battery to at least 10C-15C before driving.