Idle for long periods in the cold

[Couscous19]

Hi everyone.

I'm about to go on holiday for a fortnight which will mean leaving my MS85 idle. I don't have a home charger yet (hopefully within a month) so rely on the nearby supercharger at Westfield. This means my car will sit idle for 3 weeks without a charge or usage, starting at about 55% battery.

I assume the vampire drain and energy usage to warm up after the 3 weeks will leave me plenty of juice to make the 5 mile trip to the supercharger once I'm back?

I have heard mixed things about cold weather. While the cold is clearly not great for energy usage while the car is running, I have read that being left idle for a long time in cool temperates is, if anything, better for battery longevity and doesn't increase the rate of vampire drain. Thoughts?

I also bought the MS with the view to drive it for 15+ years so battery longevity is key to me. I'm wondering if it will do better getting a charge before I go, then sitting idle for a fortnight at 60 to 80% versus the current status of being idle for 3 weeks and going from 55% to (say) 20%.

 

[JonG]

I doubt starting at 50 or 80% will make any difference to your battery life. Running it flat would.

When leaving the car, ensure smart cinditiining and always connected are both off, and don’t connect to the car from the app, or have something like a 3rd party thing running that constantly polls the car for data, you should lose only about 1-2% a day - 55 down to 13% should be worse case, but to be safe I’d start a little higher.

 

[Solarman004]

I'm about to go on holiday for a fortnight which will mean leaving my MS85 idle. I don't have a home charger yet (hopefully within a month) so rely on the nearby supercharger at Westfield. This means my car will sit idle for 3 weeks without a charge or usage, starting at about 55% battery.

I assume the vampire drain and energy usage to warm up after the 3 weeks will leave me plenty of juice to make the 5 mile trip to the supercharger once I'm back?

@Couscous19 : If the Supercharger is 5 miles from what I'm assuming is airport parking, could you leave early on departure day, Supercharge to 90% and then park? That would certainly give you a more comfortable buffer.

 

[arg]

IMO, you are substantially over-thinking this. With always-connected off and anywhere between 50%-90% charge when you go, there should be plenty when you get back, and less impact on the battery life than if you had been at home driving it for those three weeks.

We can debate the merits of starting higher or lower - lower being notionally better while it's standing there, but traded off against worse during that trip to the supercharger, and also trading off against miscalculation or getting delayed while away and so ending up very low when you eventually return. However, all of these factors are very minor, hard to know for sure, and not really worth worrying about.

Experience suggests that the car gets into a deeper sleep when left untouched for a long time, so the 1%/day vampire draw is probably pessimistic.

 

[Couscous19]

IMO, you are substantially over-thinking this. With always-connected off and anywhere between 50%-90% charge when you go, there should be plenty when you get back, and less impact on the battery life than if you had been at home driving it for those three weeks.

We can debate the merits of starting higher or lower - lower being notionally better while it's standing there, but traded off against worse during that trip to the supercharger, and also trading off against miscalculation or getting delayed while away and so ending up very low when you eventually return. However, all of these factors are very minor, hard to know for sure, and not really worth worrying about.

Experience suggests that the car gets into a deeper sleep when left untouched for a long time, so the 1%/day vampire draw is probably pessimistic.

That's the answer I wanted to hear! I only got my car in August so still new to what the cold weather does to the physics of the battery.

 

[kort677]

first off there is a language barrier, I believe that your usage of idle means to sit for a period of non use. in that case it would be wise, if available to use a regular wall socket which will charge the car a minimal level because in cooler temps the car will use energy to keep the battery warm and keeping it plugged in will assist in maintaining a charge. if you allow the main battery to discharge then the 12v battery will be run down real quick and you'll have a hard time righting things.

 

[Tam]

...doesn't increase the rate of vampire drain...

I think that is true if you store your battery. But your Tesla main battery is not stored.

Your 12V battery is still constantly working and providing power continuously to accessory components even when your car is completely off. That in turn would drain your main battery to recharge your 12V battery periodically.

In warm weather, you would have more miles while in cold weather, you would have less miles.

So if you want to reach a Supercharger, choosing cold weather is not a good choice.

Remember, in cold weather, your main battery heater can automatically turn on to heat itself without asking you and it might drain your battery to the point that you can't reach your Supercharger just 5 miles away while it may say on the dashboard battery gauge that your battery still has plenty of miles--15 miles to start off your trip!

In a long term parking Tesla, I would worry more a about a possibility of depleted battery rather than worrying about having more than enough state of charge such as 90%...

A depleted battery, whether it's 12V or main pack, can shorten their lives.

 

[arg]

Remember, in cold weather, your main battery heater can automatically turn on to heat itself without asking you and it might drain your battery to the point that you can't reach your Supercharger just 5 miles away while it may say on the dashboard that you start off with 15 miles!

Note that you are posting in the UK forum. We don't get weather here cold enough to require the pack heater while driving.

I'm not convinced that the pack heater ever turns on when simply parked (not charging).

 

[animorph]

Plug it in to whatever you can if it's being left at home.

Just to double check your car settings versus vampire drain, check how many rated miles you are currently losing over night of any long idle period. Once you have that estimate, you could add a little charge above 50% if necessary to avoid going too low before you charge again.

 

[Tam]

I'm not convinced that the pack heater ever turns on when simply parked (not charging).

I agree. Main battery pack does not warm itself when the car is off on a parking lot. However, once you start your car, that's when it will decide on its own whether to deplete your remaining battery capacity or not.

I am not saying that it will happen in this case, but generically, I would worry more about what if something goes beyond my control and both 12V and main battery pack are depleted because it left the car parking at 55% state of charge instead of higher like 90%.

 

[arg]

I am not saying that it will happen in this case, but generically, I would worry more about what if something goes beyond my control and both 12V and main battery pack are depleted because it left the car parking at 55% instead of higher like 90%.

I agree with you in the general case. This particular case however is comfortable either way; personally I'd leave it more towards full if I had the choice, but probably not to the extent of going out specially on a trip to the supercharger it it's already comfortable.

 

[kort677]

I'm not convinced that the pack heater ever turns on when simply parked (not charging).

I agree. Main battery pack does not warm itself when the car is off on a parking lot.

That is flat out wrong. I learned the lesson the hard way. I parked the car one night while on a trip with about 45 miles range remaining. the SPC was about 20 miles away, I awoke with 18 miles of range and somehow I nursed the car to the SPC with the charge now light glowing. I called the tesla service number and was told that in cold conditions the battery pack WILL warm itself.
please don't offer advice if you really aren't 1000% sure it is valid

 

[Tam]

...That is flat out wrong...

I stand corrected!

Thanks for the correction by sharing your valuable experience.

 

[svp6]

Check Bjorn Nyland's videos on youtube, he left his car in Norway for 3 weeks, documented the drop. I left once the car at the airport for 1 week in Minnesota winter (-20C), still OK. As already mentioned, make sure you unclick "always on" and use the battery saving mode.

 

[arg]

That is flat out wrong. I learned the lesson the hard way. I parked the car one night while on a trip with about 45 miles range remaining. the SPC was about 20 miles away, I awoke with 18 miles of range and somehow I nursed the car to the SPC with the charge now light glowing. I called the tesla service number and was told that in cold conditions the battery pack WILL warm itself.
please don't offer advice if you really aren't 1000% sure it is valid

What sort of temperature was that?

It's also not clear that your anecdote is evidence that the battery is heated while parked. The range estimate on the dash is affected by temperature - both by the lower energy content of the battery when it is cold, and the need to run the battery heater for driving. So it's entirely plausible that you parked with 45 miles range on a hot battery; the same battery when cold had only (say) 30 miles of range on an equivalent basis, and was so cold that the heater needed to be used while driving so the range estimator knocked off a further 12 miles to account for that.

It's possible that the car does heat the battery when parked in conditions so cold that it could be damaged by the temperature (below -30C), though that would be an act of desperation - it doesn't know when you are coming back, and raising the battery temperature more than a trivial amount above ambient would consume all of the battery power in a short time.

In any event, we don't get these extreme temperatures in the UK, and certainly not in London where the OP is based.

 

[WannabeOwner]

This means my car will sit idle for 3 weeks without a charge or usage, starting at about 55% battery.

Not clear to me whether you are going to park the car at home, or at airport?

If at home, and given that Supercharger is nearby, I would charge it more. Above 70% the Supercharging-rate will slow down, more significantly above 80% and very significantly above 90%. I would suggest not leaving the car standing for long above 90% (that's as a general rule, although also I would not be too worried about it - if once or twice in its lifetime you charge to 100% and then "don't make that planned trip" then from all that I have read that's not significant. There are other opinions of course ... but also plenty of commentary that charging full, or keeping it as close to 50% as possible or [insert other battery-saving plan here] ... makes very little difference. "Don't leave it standing above 90% nor below 10%" covers 99.9% of the advice that I have read.

So ... with that in mind ... if parking at home I would charge to 90% at supercharger and abandon the car at home for your holiday. Have a good time! Whilst you say that you don't have a dedicated charger at home could you use a 13AMP plug? That would do to keep the car topped up - indeed, in the time that you are on holiday it would charge the car nicely! Assuming no secure socket, whilst you are away, trailing a lead through a window should get you 5 or 6 miles-per-hour charge.

If you are going to abandon the car at the airport then I would charge as much as you can (e.g. anything approaching 90%) at the nearest supercharger to the airport and leave it at that - making sure that you will have enough charge to then get to a supercharger (or home) when you get back. Presumably the airport doesn't have a charger? nor a concierge service that will Valet park the car and charge it? You might be surprised ...

If you are worried about parasitic battery drain whilst you are away then change the password on your My Tesla account, and don't use any APPs whilst you are away (or if you use loads of APPs - I know that I do - then maybe just modify that to "Change password and only use one phone APP whilst away"

 

[culverwood]

Just left my car at Heathrow for 3 weeks - supercharged as suggested at the Tesla showroom nearby (where I had originally collected the car from) to a reasonable level and made sure not to use the App while on holiday and that the "always on" was off. Minimal loss of charge < 1% per day.