Keep it plugged in or let it run down?

[SSD420]

I'm back.

What happens if my MX battery completely dies? Do I just plug in and wait for it to turn back on, just like any other electronic? Or is that really really bad to let it drain to 0%?

 

[goneskiian]

I'm back.

What happens if my MX battery completely dies? Do I just plug in and wait for it to turn back on, just like any other electronic? Or is that really really bad to let it drain to 0%?

It's really bad to let it completely die, but 0% isn't completely dead. To "brick" it you'd have to leave it unplugged in the winter for a few weeks. Many folks have actually driven over 10 miles or so after 0%. Tesla is smart and has held a reserve for those of us that like to push boundaries!

There are lots of threads on this in the S forums. Check 'em out!

 

[Rocky_H]

It's really bad to let it completely die, but 0% isn't completely dead. To "brick" it you'd have to leave it unplugged in the winter for a few weeks. Many folks have actually driven over 10 miles or so after 0%. Tesla is smart and has held a reserve for those of us that like to push boundaries!

There are lots of threads on this in the S forums. Check 'em out!

Jeez, PLEASE stop spreading this myth! There did used to be a small driving reserve below 0 miles, but it was removed in a software update a couple years ago (around version 5.6, I think). There generally is NO driving reserve now, and I found several reports here on this forum of people’s cars shutting down right at 0, or within plus or minus a couple. Yes, I did say “plus”. A couple of the shutdowns have happened with about 2 still showing on the range. So please stop spreading that B.S.; it’s dangerous to tell people that, as they will count on it, and it will leave them stranded.


That is different from the anti-bricking reserve. It is very damaging for lithium ion batteries to actually go to 0% charge, so Tesla helps save you from destroying your car’s battery by shutting down the car with a few kwh still in there.

 

[Scrith]

Data point: I got my X down to 2 before plugging in at the Gilroy supercharger on Saturday. Living with a LEAF for 3 years before the X got me pretty bold about stretching it. ;-)

 

[SSD420]

Jeez, PLEASE stop spreading this myth! There did used to be a small driving reserve below 0 miles, but it was removed in a software update a couple years ago (around version 5.6, I think). There generally is NO driving reserve now, and I found several reports here on this forum of people’s cars shutting down right at 0, or within plus or minus a couple. Yes, I did say “plus”. A couple of the shutdowns have happened with about 2 still showing on the range. So please stop spreading that B.S.; it’s dangerous to tell people that, as they will count on it, and it will leave them stranded.


That is different from the anti-bricking reserve. It is very damaging for lithium ion batteries to actually go to 0% charge, so Tesla helps save you from destroying your car’s battery by shutting down the car with a few kwh still in there.

Thank you for this @Rocky_H . It's good to know that someone is looking out for us newbies who are being fed incorrect info.

 

[thecloud]

If you charge up at that supercharger close to you several times expect a call from Tesla. They are not fond of local supercharging. They see and now promote supercharging as free for long distance travel.

And yet, Tesla still shows me this image whenever I visit their forums. Why would they go out of their way to point out my local supercharger to me, if their policy is to discourage local supercharger use?

p.s. I've used that supercharger exactly once, and that was to charge the loaner Tesla while mine was in for service. So I've never actually charged my car there yet.

 

[jerry33]

A plugged in Tesla is a happy Tesla. Leave it plugged in and avoid the extremes whenever possible. It's fine to do a full range charge if you need the range and are going to be driving right away; don't let it sit above the daily line for an extended period. If you get down to where the battery indicator is no longer green plug it in as soon as you can.

 

[goneskiian]

Jeez, PLEASE stop spreading this myth! There did used to be a small driving reserve below 0 miles, but it was removed in a software update a couple years ago (around version 5.6, I think). There generally is NO driving reserve now, and I found several reports here on this forum of people’s cars shutting down right at 0, or within plus or minus a couple. Yes, I did say “plus”. A couple of the shutdowns have happened with about 2 still showing on the range. So please stop spreading that B.S.; it’s dangerous to tell people that, as they will count on it, and it will leave them stranded.


That is different from the anti-bricking reserve. It is very damaging for lithium ion batteries to actually go to 0% charge, so Tesla helps save you from destroying your car’s battery by shutting down the car with a few kwh still in there.

Thank you for this @Rocky_H . It's good to know that someone is looking out for us newbies who are being fed incorrect info.

My apologies. I didn't knowingly spread incorrect information. It was a mistake born of ignorance and I should have qualified my response with an "AFAIK". I was not aware of the removal of the driving reserve. @Rocky_H can you point me to some threads that discusses this so I can get the current facts? Thanks. I'll go looking for some as well.

 

[Roentgen]

Was gone for a week, and left my X plugged in. Battery was at 90% with 230 rated miles. I lowered the charge setting to 60%.

At the end of the vacation, my X was still 219 rated miles! Not bad.

Interestingly, the rated mileage was up to 231 after the next recharge (re-set back to 90%).

 

[Rocky_H]

My apologies. I didn't knowingly spread incorrect information. It was a mistake born of ignorance and I should have qualified my response with an "AFAIK". I was not aware of the removal of the driving reserve. @Rocky_H can you point me to some threads that discusses this so I can get the current facts? Thanks. I'll go looking for some as well.

I know you weren’t intentionally doing it. It’s just one of those things that used to be the case some time ago, and people heard about it, but then things changed, and people just keep repeating it. I remember back then. There were people repeating this experiment running their cars to shut down on purpose, trying to find the exact number of miles it was and arguing about what the number was. But it never was an actual number of miles, because it was just some mismeasurement of the capacity or maybe Tesla trying to be a little overcautious to protect people, and the number of miles varied a lot, if you started going uphill, or ran the heat or whatever. At one point the algorithm got changed and became much more accurate so that 0 really was pretty much the point at which the car will shut itself off. I don’t know if any of us know exactly what the change was because it’s “secret sauce”. Maybe they remapped a couple of kwh into the usable range because they thought they were being a little too conservative. Maybe they just found a more accurate way of detecting the charge level. Who knows what actually happened there? It’s just important to tell people that they should really count on 0 being 0, because that’s pretty much how the cars actually behave these days most of the time. Sure, some people will be lucky and go below, but we should warn people to not count on that.



Here are some links to discussions about this topic that I found with a search on the terms: “shut down miles reserve”



0 miles rated range



Has anyone ever been stranded with an empty battery?



Out of juice - battery issue, UI issue, or user mistake?



built in exta mileage with in the battery?

 

[mlouie23]

Was gone for a week, and left my X plugged in. Battery was at 90% with 230 rated miles. I lowered the charge setting to 60%.

At the end of the vacation, my X was still 219 rated miles! Not bad.

Interestingly, the rated mileage was up to 231 after the next recharge (re-set back to 90%).

Thanks for the advice @Roentgen .
While on vacation, is 60% the sweet spot? Why not 50%, 40%, or 75%?
Thanks for sharing the knowledge!

 

[thecloud]

You can't set the slider position to anything lower than 50%. That is generally considered the optimal state of charge to maintain if the battery is going to sit for a while without being used. You want to avoid the two extremes: either sitting for a while at a full state of charge, or (obviously) running down completely to empty. This article is good reading. This one too.

 

[EV-lutioin]

Just curious why the Tesla mobile connector bundle doesn't come with this 240 plug? Many 240V dryer receptacles come with this set up. There are several other 240 plugs as well. The Tesla website says, "Anywhere. Seriously. Where there's an outlet, you can charge." but what if the outlet is one of these alternate 220/240 set ups? I am looking into charging at an RV park in Chester, CA and they don't have the 4 prong 240 receptacle that comes in the connector bundle.

 

[thecloud]

There are two common types of 240V/30A dryer receptacles, NEMA 10-30 (3 prong with angled blades, as in your photo) and NEMA 14-30 (4-prong, similar to the 14-50 adapter that comes with the mobile connector bundle, but with one of the prongs being L-shaped.) Tesla used to provide these adapters as alternatives you could purchase separately online, but then they were abruptly discontinued last year. It's unclear why they've stopped selling the 30 amp adapters or whether they'll ever come back, but currently your only alternative is to either make or purchase a 3rd-party adapter cable.

 

[thecloud]

...NEMA 10-30 (3 prong with angled blades, as in your photo)...

Sorry, I didn't look carefully enough at your photo. That's actually a picture of a NEMA 10-50 plug, not a 10-30. The difference is that the middle prong is a flat blade, whereas the 30-amp version is L-shaped.

 

[msnow]

Jeez, PLEASE stop spreading this myth! There did used to be a small driving reserve below 0 miles, but it was removed in a software update a couple years ago (around version 5.6, I think). There generally is NO driving reserve now, and I found several reports here on this forum of people’s cars shutting down right at 0, or within plus or minus a couple. Yes, I did say “plus”. A couple of the shutdowns have happened with about 2 still showing on the range. So please stop spreading that B.S.; it’s dangerous to tell people that, as they will count on it, and it will leave them stranded.


That is different from the anti-bricking reserve. It is very damaging for lithium ion batteries to actually go to 0% charge, so Tesla helps save you from destroying your car’s battery by shutting down the car with a few kwh still in there.

How would you describe anti-bricking? I always thought it was a reserve.

Edit: never mind. I figured it out. It allows you to be able to be towed somewhere where you can charge it.

 

[Rocky_H]

How would you describe anti-bricking? I always thought it was a reserve.

Edit: never mind. I figured it out. It allows you to be able to be towed somewhere where you can charge it.

Yes, people used to talk about the anti-bricking reserve at the very bottom, then the “below 0” driving reserve (not really there anymore), and then the usable portion above 0. The anti-bricking reserve is definitely still there. That is to prevent the battery from really getting damaged, and that portion is never accessible under any circumstances. The car will shut down before going into that to make sure it can be charged up and used again.

 

[Donaldsue]

I live in a condo and we are installing a small number of chargers. People say we should share them, but I'm worried about the "Keep it plugged in" mantra; other owners say that doesn't make sense and i should ignore it. So: 1. is there a way to find out what the actual purpose of keeping it plugged in is, that would satisfy engineer types? and 2. is keeping it plugged into 110 V sufficient for this purpose? --New, intimidated model 3 owner.

 

[jerry33]

I live in a condo and we are installing a small number of chargers. People say we should share them, but I'm worried about the "Keep it plugged in" mantra; other owners say that doesn't make sense and i should ignore it. So: 1. is there a way to find out what the actual purpose of keeping it plugged in is, that would satisfy engineer types? and 2. is keeping it plugged into 110 V sufficient for this purpose? --New, intimidated model 3 owner.

The actual purposes to keeping it plugged in are:

1. Smaller charge cycles equals longer batter life. An example with numbers chosen for convenience (I don't believe anyone outside Tesla knows the real numbers). A 200 mile battery with 600 full cycles of life is 120K miles. However, if each cycle is 50 miles, it might have 5000 or 6000 cycles which is 250-300K miles.

2. Some heating and cooling functions use the wall power to replace battery drain while it's happening (others don't).

For 120V it depends upon the temperature. If it's cold enough, 120V 15 amp will barely be enough to keep the battery warm and no charging will occur. In any reasonable temperature, 110V will be enough although 3-4 miles per hour is all you can expect from 120V 15 amp.

For an anecdote, my 5.75 year old S85 with 119K miles is plugged in when possible and has lost between upper 3% and lower 4% (depending upon temperature) as best I can tell. It will probably be always in the lower 4% range next summer.

 

[travwill]

All these post and the original hypothetical was never answered.

In general I'd say that if you run out of the ability to drive, the battery pack still has that bricking reserve left. Not sure if it routes any energy to the 12v at that point. But, if you get it to a charger somehow then it should start charging. If your main battery is dead (not fully bricked) and your 12v is also dead... then I'd say your screwed fully. You would have to have the 12v replaced likely first before anything is possible with the main battery again since all electronics/controllers in the car would be dead.