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Bad battery heater?

Mayhemm

Model S P85+ "Lola"
Nov 9, 2012
1,966
32
Saskatchewan, Canada
I've always been under the impression that when you use the mobile app to precondition the car in cool weather it will also trigger the battery heater if you're plugged in. However, today I warmed the car for a full 30 minutes but still had limited regen for about 30km. The ambient temp was about 8C. Given the amount of time I allowed, why was the battery not warmed sufficiently to allow full regen? It wasn't that cold out.

Has the battery warming behavior been changed in the new software (I'm on 7.0.56) or is it possible my battery heater is malfunctioning?
 

travwill

Active Member
May 1, 2015
1,446
662
Marble Falls, TX
From what I understand, it heats the batter a little when being used, discharging. I believe though that the batter warms more when charging - that is when you see the videos suggesting you try to time your charge ending right before you leave when its cold. The heater on its own just kicks in when very cold to protect battery capacity from dropping too much.
 

Cottonwood

Roadster#433, Model S#S37
Feb 27, 2009
5,088
166
Colorado
I've always been under the impression that when you use the mobile app to precondition the car in cool weather it will also trigger the battery heater if you're plugged in. However, today I warmed the car for a full 30 minutes but still had limited regen for about 30km. The ambient temp was about 8C. Given the amount of time I allowed, why was the battery not warmed sufficiently to allow full regen? It wasn't that cold out.

Has the battery warming behavior been changed in the new software (I'm on 7.0.56) or is it possible my battery heater is malfunctioning?

The battery heater won't kick in along with climate, when you have "Range Mode" on, even if the car is on shore power.
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,868
Toronto, ON
The battery heater won't kick in along with climate, when you have "Range Mode" on, even if the car is on shore power.

Good point. And even if not in Range Mode, you may have to pre-heat for a long time to completely eliminate the re-gen limits. In the depths of winter, I pre-heat for about 20 minutes and the cabin is nice and toasty, but it barely puts a dent in the re-gen limit. What it does do (based on casual observations) is help the re-gen limits disappear more quickly once I'm under way. Another trick is to try and schedule your charging so that it ends right around when you plan on leaving. Then the battery will be warm(er) from charging. Personally, I don't really care if the re-gen is limited under these conditions, but then I tend to get on the freeway and cruise to work, so I'm not doing as much start/stop as others may be on their commutes.
 

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,024
1,013
My experience has been that cabin pre-heating for 30-60 minutes will "soften" the blow of regen limitations, but I've never had full regen after merely preheating the cabin. Only after battery charging have I experienced this.
 

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Mar 8, 2012
19,729
22,808
Texas
My experience has been that cabin pre-heating for 30-60 minutes will "soften" the blow of regen limitations, but I've never had full regen after merely preheating the cabin. Only after battery charging have I experienced this.
This has been my experience as well. At -5 to 0C you'll get the yellow dashes at about 30 if you set the timer to finish at departure, have range mode off, and preheat for two cycles.
 

apacheguy

S Sig #255
Oct 21, 2012
5,083
1,243
So Cal
This is why I don't fully trust the thermal management of the BMS. If the car is drawing any amount of power, especially when pre conditioning, which means I'm going to drive it soon, why doesn't it aggressively maintain the pack temps?

I would love to see a battery condition mode separate from pre-con that operates both in the cold as well as in heat.
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,868
Toronto, ON
If the car is drawing any amount of power, especially when pre conditioning, which means I'm going to drive it soon, why doesn't it aggressively maintain the pack temps?

My guess is because that would use a lot more energy. The pack generates it's own heat once it starts discharging, so to pre-heat it all the way up to this point on electricity you're paying for is not very efficient. Even though electricity is relatively cheap, that doesn't mean it should be wasted, creating additional GHG in the process.
 

Mayhemm

Model S P85+ "Lola"
Nov 9, 2012
1,966
32
Saskatchewan, Canada
The battery heater won't kick in along with climate, when you have "Range Mode" on, even if the car is on shore power.

I was aware of this. For me, Range Mode seems to really mess with the HVAC (either fogging up the windows or just making the cabin seem overly drafty and humid) so I never use it. Thanks for the reminder, though.

In the depths of winter, I pre-heat for about 20 minutes and the cabin is nice and toasty, but it barely puts a dent in the re-gen limit. What it does do (based on casual observations) is help the re-gen limits disappear more quickly once I'm under way. Personally, I don't really care if the re-gen is limited under these conditions, but then I tend to get on the freeway and cruise to work, so I'm not doing as much start/stop as others may be on their commutes.
As I mentioned in my post, the ambient temp was only about 8C; hardly the depths of winter (though, I suppose that's all relative :tongue:). Most of my daily trips are too short to finish heating the battery.


My experience has been that cabin pre-heating for 30-60 minutes will "soften" the blow of regen limitations, but I've never had full regen after merely preheating the cabin. Only after battery charging have I experienced this.
Huh, this would appear to be my experience as well. Maybe the discussion I'm remembering operated under the assumption that one would always be driving for an extended period after pre-conditioning the car (such as in preparation for a roadtrip). Oh well, this is hardly a serious issue (especially in light of the giant facepalm that is FW7.0) and I was just curious if I'd remembered incorrectly. It's always nice to be able to regen to a stop on the way to work as much as possible. Using the brakes seems so archaic now. :biggrin:
 
Last edited:

MassModel3

Member
Aug 19, 2014
907
254
MA South Shore
Another thing to consider is that sometimes you don't want the battery to warm up when you remotely heat your cabin.

If you pull over to a rest area for a few hours shut-eye because you just can't focus any longer, you might use the remote access to run the heater for 30 minutes at a time, but you don't want the battery drawing extra power to heat itself while you're sleeping. Other option would be to keep your door open, but that's ill-advised while sleeping in a strange rest area.

Also, smart preconditioning, when enabled, warms your cabin because the car thinks you will be using it soon. If you don't really use it, you don't want to waste the battery heating the battery. Same applies if you intentionally enable the cabin heater but you don't leave when you intended.

My point is, I can definitely see why Tesla would not fully heat the battery to optimal driving temperature when you're not really driving.
 

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,393
Ithaca, NY
Yes, you now have to set it to high to get the same temperature as 24 last winter.

This is really nuts.

I had thought I was noticing a difference, but it hasn't been that cold here yet, so I wasn't sure.

I already was heating the cabin for no real reason other than pack heating purposes, as I like the cabin fairly cool when I drive. I set the cabin temperature to 64 F degrees usually, but I'll warm the car, to warm the pack, at 72 F or even higher. So after preheating, I wind up cooling the car when I actually start driving.

There's no way I'm going to heat the cabin on high for an extended time, just to warm the pack.

Why in the world can't Tesla give us a separate pack heating function? Anyone interested in this, please write to Tesla, as I have, and ask for an option to preheat the battery pack independent of cabin heating, range mode, etc. The more of us that write, the greater the likelihood that Tesla may eventually provide this.

Thanks.
 

Lanber

Member
Sep 20, 2015
64
30
Norway
With 7.0 the car became more conservative with limits on regen regarding temperature. Live in Norway and I sure notice this with a colder climate.

Last week I was in Oslo and temperature was just around freezing, drove there 300km and worked 5h, then took car out of range mode to heat battery while driving to Drammen SC, that was 50km away. Only in the hill just before SC did my limit go away aperently. On the SC I was alone and the car throttled back power to 70kw even though I had like 5% left. Charged as little I dared (I pretty thick skinned now having driven Teslas for 2 years) and set off for Porsgrunn SC, arrived there with 1%. Full power on SC there
 

spottyq

Member
May 7, 2015
278
49
Belgium
This is really nuts.

I had thought I was noticing a difference, but it hasn't been that cold here yet, so I wasn't sure.

I already was heating the cabin for no real reason other than pack heating purposes, as I like the cabin fairly cool when I drive. I set the cabin temperature to 64 F degrees usually, but I'll warm the car, to warm the pack, at 72 F or even higher. So after preheating, I wind up cooling the car when I actually start driving.

There's no way I'm going to heat the cabin on high for an extended time, just to warm the pack.

Why in the world can't Tesla give us a separate pack heating function? Anyone interested in this, please write to Tesla, as I have, and ask for an option to preheat the battery pack independent of cabin heating, range mode, etc. The more of us that write, the greater the likelihood that Tesla may eventually provide this.

Thanks.

Does the pack pre-heating depends on the temperature you set for the cabin ? Or do I read you wrong ?
(I can't see a reason why that would be so; either the pack is being warmed to a certain temperature or it is not, but I can't see any reason why Tesla would let us change that setpoint…)

I think it should heat the pack to its usual temperature regardless of the cabin setting (so, even if it is set to LO) when you pre-heat with the app. Or is it not so ?

It is certainly technically possible since the cabin and the battery each have their own heater.
 

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Mar 8, 2012
19,729
22,808
Texas
Does the pack pre-heating depends on the temperature you set for the cabin ?
I don't have a good handle on that. I suspect that if the setting is so low the cabin doesn't heat, then the pack won't heat either, but if any actual cabin heating is occurring, then the battery will heat but what it heats to is probably not dependent upon the set temperature. However, this supposition needs confirmation. What I know is that the cabin heat has to be set to HI to get the same amount of preheat warmth that 24-26 gave last winter and the winter before. Also the defroster blows out cold air regardless of whether it's set on blue or red, which nullifies the preheating of the cabin.
 

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,393
Ithaca, NY
Does the pack pre-heating depends on the temperature you set for the cabin ? Or do I read you wrong ?
(I can't see a reason why that would be so; either the pack is being warmed to a certain temperature or it is not, but I can't see any reason why Tesla would let us change that setpoint…)

I think it should heat the pack to its usual temperature regardless of the cabin setting (so, even if it is set to LO) when you pre-heat with the app. Or is it not so ?

It is certainly technically possible since the cabin and the battery each have their own heater.

I was thinking that perhaps now it did, based, perhaps on my incorrect understanding of Jerry's post, combined with what I had been observing recently. In retrospect I expect what I've been observing is just the recent changes with respect to more conservative regen limits due to the cold in general.

I maintain my position, though, that it is crazy that we have to be thinking about this so much and trying to tweak things and possibly wasting energy heating our cabins beyond the point we want them heated just to accomplish something that could easily be accomplished if Tesla just provided the option to do it.

Tesla has now provided the Max Battery Power option, which is a battery heating option, to a small subset of cars--the Performance models--so that they may eke out an extra couple of tenths of a second in 0-60 launches. That's fine. But now it's time for them to provide a very similar option to the entire fleet that will have a much broader and much more practical application. We need a battery preheating option, and we need it now!
 
Jan 1, 2015
247
76
Norge
I started using max battery power to heat up my battery. It usually say 1 hour + + left. When it's 20 min left, I stop it. Then I can drive without use my battery to heat up itself. After 7.0 this is the only way I can get low numbers without driving 60min +
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,868
Toronto, ON
With 7.0 the car became more conservative with limits on regen regarding temperature. Live in Norway and I sure notice this with a colder climate.

I have noticed the same thing. I see regen limits at temperatures a lot higher than was the case in the past. It makes me wonder what harm I was doing to the battery for the past three years when I had no regen limits at similar temperatures.

- - - Updated - - -

Also the defroster blows out cold air regardless of whether it's set on blue or red, which nullifies the preheating of the cabin.

For me, that seems to have been fixed with 2.9.12
 

apacheguy

S Sig #255
Oct 21, 2012
5,083
1,243
So Cal
Temps were in the 30s this morning. I had to swing over 5 miles from our hotel to a SpC so I pre conditioned the car for about 30 minutes prior.

Battery did NOT heat whatsoever. Even after 15 minutes of charging the rate was limited to 60 kW (I was at 33% SOC). Tesla tech support claimed the battery was at 18 C and no faults were showing. Did 7.0 disable the battery heater altogether?
 

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