Does pre-conditioning = Defrost functi

[rob@rar]

Mildly concerned to see reports of cracked windscreens (possibly) as a result of using the Defrost function in the cold weather we’re having. Usually I turn on the climate control about 10 minutes before I head out for my usual commute, and this is enough to warm the cabin and melt the frost on the windscreen so I’ve not been tempted to use the Defrost function. However, I have a few long drives coming up, which are likely to begin in very cold temperatures so I’m wondering whether I should use the Pre-condition function to warm the battery pack (while plugged in to my charger) so increase range and efficiency. Is setting the Pre-condition function the same as using Defrost function, and if so is there a slight risk of a windscreen crack?

Trying not to be paranoid about this, but discovering a cracked windscreen at the start of a long drive to the Alps would be a major PITA.

 

[Js1977]

I always just turn climate on and dont bother with defrost. We roughly know these days how long it will take to defrost based on what we see outside.

Lately ive found that the battery warming just comes on when I turn the climate on in the morning but dont know what has changed.

If its dark, its just the headlights that either need scraping or some tepid water.

 

[GRiLLA]

It is the same, Ive used it every winter without issue. These broken windscreens are a significantly rare occurrence.

 

[rob@rar]

It is the same, Ive used it every winter without issue. These broken windscreens are a significantly rare occurrence.

Thanks for the re-assurance. I appreciate that windscreen cracks are likely to be extremely rare. I guess one of the downsides of using social media to share experience is that while it is mostly very helpful to learn from more experienced Tesla owners, it is easy to dwell on rare examples of unfortunate cases and worry that the chance of similar happening to you is higher than it actually is.

 

[Jason71]

It is the same, Ive used it every winter without issue. These broken windscreens are a significantly rare occurrence.

Are you sure "precondition" is the same as "defrost"? I would have thought precondition was the same as switching on climate from the app which is not the same as defrost which is a separate option in the app. Defrost pretty much whacks the climate up to max. I don't think pre-condition does that. That would not make sense.

 

[EV_Travels]

Preconditioning is not defrosting. Defrosting is a separate button on the phone app. Preconditioning or turning on the heat to warm up the car before you enter just turns on the seat heaters and the ventilation heat. I park outside at work and usually from about now until April, for the past 5 years, I turn on the heat as well as defrost every day before I leave. No problems whatsoever.

 

[WllXM]

Preconditioning is not defrosting. Defrosting is a separate button on the phone app. Preconditioning or turning on the heat to warm up the car before you enter just turns on the seat heaters and the ventilation heat. I park outside at work and usually from about now until April, for the past 5 years, I turn on the heat as well as defrost every day before I leave. No problems whatsoever.

Defrosting is just putting climate on max heat and directing it to the windscreen instead of the cabin blowers (+ activating the rear window defrost).

As a rule of thumb I created an Apple Shortcuts automation based on a couple months of trial and error in the winter:

In the morning, when > 10° -> do nothing
When > -2°C -> Precondition
When <= -2°C -> Precondition AND Defrost

 

[Jason71]

Defrosting is just putting climate on max heat and directing it to the windscreen instead of the cabin blowers (+ activating the rear window defrost).

As a rule of thumb I created an Apple Shortcuts automation based on a couple months of trial and error in the winter:

In the morning, when > 10° -> do nothing
When > -2°C -> Precondition
When <= -2°C -> Precondition AND Defrost

Nice idea. Personally though I think I would just turn on the precon earlier for lower temps and forgo the defrost.
Seems to me that Defrost is best used only when you are in a hurry. Precon is more than capable of melting ice on the car given 10 minutes in my experience and is less likely to crack anything.

 

[robbieduncan]

Maybe Ice. Defrost melted 5cm of snow off the car!

 

[Andiamo]

I live in Ontario where it is about to get cold and I just picked up my car. I was told to pre-condition the battery for a period of time prior to departure based on temperature. To begin the pre-conditioning, I only had to change the cabin temperature and that would begin the pre-conditioning as well as warm the cabin. Other than the On/Off, Defrost, and Vent icons, I don’t see any ’pre-conditioning’ icons on my phone App. Am I missing something? Is there a specific way to begin the process?

 

[Jason71]

I live in Ontario where it is about to get cold and I just picked up my car. I was told to pre-condition the battery for a period of time prior to departure based on temperature. To begin the pre-conditioning, I only had to change the cabin temperature and that would begin the pre-conditioning as well as warm the cabin. Other than the On/Off, Defrost, and Vent icons, I don’t see any ’pre-conditioning’ icons on my phone App. Am I missing something? Is there a specific way to begin the process?

There is no separate battery pre-condition option. if you turn on the climate it will warm up the cabin and if the battery needs warming ( which for you I guess it will) it will also warm that. I think an orange wavy icon appears on the home screen in the top left by the battery percent while this is happening if memory serves.

 

[WllXM]

Also bear in mind that it'll probably only take 5-10 mins to bring your cabin to temperature (and you'll receive a notification that it has done so in the app), but for optimal battery preconditioning before a medium to long drive, Tesla recommends at least 30-45mins IIRC...

 

[Andiamo]

Thank you both for your info and quick responses. As a follow-up - once the cabin reaches temperature, will the battery warming continue?

 

[Jason71]

Thank you both for your info and quick responses. As a follow-up - once the cabin reaches temperature, will the battery warming continue?

I believe so but in the UK TBH its not generally too much of an issue. the battery heater icon usually goes off before the cabin is up to temp!

 

[Terry35]

The first (and only) time I used the remote defrosting function, my windshield cracked. Tesla claimed this was not caused by the remote defroster because there was a microspic (invisible) chip in the windshield that caused the crack once the defroster was turned on, and so my 15-month old windshield was not covered by the warranty. I will not beusing the remote defroster again, since $1,500 semms like a high cost for this”convenience”.

 

[Jason71]

The first (and only) time I used the remote defrosting function, my windshield cracked. Tesla claimed this was not caused by the remote defroster because there was a microspic (invisible) chip in the windshield that caused the crack once the defroster was turned on, and so my 15-month old windshield was not covered by the warranty. I will not beusing the remote defroster again, since $1,500 semms like a high cost for this”convenience”.

Windscreens do typically do crack under extremes of temperature such as being very cold on the outside and hot on the inside due to the thermal stress but only if there is a fault in the glass that acts as a weak spot. If not then this would happen all the time.
The only question is really was it a stone chip or a fault in the glass. Tesla clearly giving themselves the benefit of the doubt on this one not surprisingly.
I do though sometimes think EV's are more prone to this. An ICE when defrosting typically has a cold engine so the air used to defrost is not very warm so there is less thermal shock than with an EV that is able to blow very hot air almost instantly.

Similar thing happened to me in reverse. Hot sun on a cold windscreen. I was able to trace the crack back to what was clearly a stone chip.
Here in the UK our insurance policies typically cover windscreens with a very low excess, deductible I think you would call it. So mine was replace for less than $150 fortunately.

 

[ACarneiro]

Windscreens do typically do crack under extremes of temperature such as being very cold on the outside and hot on the inside due to the thermal stress but only if there is a fault in the glass that acts as a weak spot. If not then this would happen all the time.
The only question is really was it a stone chip or a fault in the glass. Tesla clearly giving themselves the benefit of the doubt on this one not surprisingly.
I do though sometimes think EV's are more prone to this. An ICE when defrosting typically has a cold engine so the air used to defrost is not very warm so there is less thermal shock than with an EV that is able to blow very hot air almost instantly.

Similar thing happened to me in reverse. Hot sun on a cold windscreen. I was able to trace the crack back to what was clearly a stone chip.
Here in the UK our insurance policies typically cover windscreens with a very low excess, deductible I think you would call it. So mine was replace for less than $150 fortunately.

Really interesting, hadn't thought of the reverse shock.
Two of my family members back home have Teslas and obviously cool the car before starting a journey in the Summer.
Cabin temperatures can be in excess of 60 degrees and so far neither of them has ever had a windscreen cracked (he says, jinxing them).
I would imagine it may be because the motorways are infinitely better looked after and it's a rarity to get a stone chip hitting the windscreen.

 

[Js1977]

Cabin temperatures can be in excess of 60 degrees and so far neither of them has ever had a windscreen cracked (he says, jinxing them).

Cabin temperature protection?

 

[KennethS]

Really interesting, hadn't thought of the reverse shock.
Two of my family members back home have Teslas and obviously cool the car before starting a journey in the Summer.
Cabin temperatures can be in excess of 60 degrees and so far neither of them has ever had a windscreen cracked (he says, jinxing them).
I would imagine it may be because the motorways are infinitely better looked after and it's a rarity to get a stone chip hitting the windscreen.

Tell that to my brother in North Carolina.

 

[ACarneiro]

Cabin temperature protection?

Sometimes the option is greyed out for some reason…