Warning - Auto-presenting doors & charging

[gmtom1]

For those X owners that have the auto-presenting doors turned on, make sure the doors re-close when you're at home and plugged in/charging.

My X is parked such that sometimes when I'm walking through the house with my keys, the car will sense and pop open the door. It normally re-closes automatically (as designed) once I walk away and the key is out of range, but this weekend it didn't. I haven't received the diagnosis from tesla service yet, but I think somehow a confluence of events led to my closed garage being filled with a strong sulfur vapor and a dead X that had to get towed on a Saturday evening.

I think it was a combo of : (1) the open door; (2) the car was actively charging; and (3) some other flaw led to the 12V battery being overcharged, resulting in a leaking battery. From what Google tells me, an overcharged 12V lead acid battery can leak and that's what creates the sulfur smell. What was concerning is that it happened in an enclosed garage and from what I've searched, the gas that's produced from overcharging is potentially flammable. Fortunately, I discovered it in time.

 

[BigMskiman]

I don't know about the rest of your hypotheses, but walking though the house should not open any doors.
Normal behavior is you approach the car from rear driver-side, it opens fully.
Normal behavior is you approach the car from front driver-side, it opens partially, then fully when it sees you pass to enter.

Other behavior while far away inside house, needs a service center (SC) opinion/fix.

 

[Evoforce]

More than likely, your battery developed an internal short. That is common for a lead acid battery. It caused the cells to boil because the traction battery tried to keep the voltage up to spec on the 12 volt battery with one cell dead thus overcharging the remaining good cells. This overcharging of the other good cells creates gassing.

 

[gmtom1]

It was a bad 12V. The tech didn't really say why or what could have caused it, since they just replaced it without further investigation. The service advisor told me that they get a lot of 12V failures, and her opinion was it's a design problem, because of the heavy loads placed on the 12V and high cycle counts tend to make the battery fail much faster than in an ICE car. They even use deep cycle batteries, but still most 12V batteries in Teslas only last 2 years max. Certainly bears out with my experience on this X and my S before that.

 

[Evoforce]

So that is why I replaced mine with a lithium 12 volt battery from element3batteries.

 

[vandacca]

So that is why I replaced mine with a lithium 12 volt battery from element3batteries.

Do you have an X or S? I noticed that the website indicates it's for Model-S vehicles only. I can't image there being much of a difference between the X and S, so I expect it to work. Just looking for confirmation from someone who actually did it.

 

[Peteski]

I simply don't trust the auto-presenting doors. It's a cool feature, but I've read too many stories about them opening unexpectedly like this. I park in far too many places where a rogue opening would be a total disaster! Actually even opening as designed would sometimes be an issue on approach. So I switched off that feature when I took delivery (actually it was switched off already) and simply press the door button instead. It may be a bit old school, but it's definitely safer, lol!

 

[Evoforce]

Do you have an X or S? I noticed that the website indicates it's for Model-S vehicles only. I can't image there being much of a difference between the X and S, so I expect it to work. Just looking for confirmation from someone who actually did it.

Well, I have an S, but I would directly contact that supplier and pose your questions directly to them. Good luck! I have been very happy with mine. I wouldn't think there is any difference either but... ask them and let us all know please.

 

[nowtleft]

Service told me that new 12v batteries are bullet proof and will last life of car. Tesla designed not off the shelf old ones.

 

[Evoforce]

Service told me that new 12v batteries are bullet proof and will last life of car. Tesla designed not off the shelf old ones.

Ha! Most lead acid batteries in all types of vehicles in the US will last between 3-5 years. I do not consider that the life of the car. Model S has been known for shorter 12 volt battery life. I do not know the stats for Model X in this regard.

 

[DCGOO]

So that is why I replaced mine with a lithium 12 volt battery from element3batteries.

Changing out an AGM Lead Acid battery with a Lithium is actually quite hazardous. I would not recommend doing that. Besides, replacements are always free (warranty) from Tesla.

 

[Evoforce]

Changing out an AGM Lead Acid battery with a Lithium is actually quite hazardous. I would not recommend doing that. Besides, replacements are always free (warranty) from Tesla.

Um, No! Please read up on this battery. This particular battery was produced to use in the Tesla. Some people with older Tesla's are out of warranty. Not the X yet of course. It is some hassle to have a dead 12 volt (lead acid) too often. It has been a common problem for Model S. I personally don't know the stats for the X in this regard for longevity, but this appears to be at least one failed (lead acid) battery.

 

[gmtom1]

I don't care much about the failing 12V. What did concern me (and they were unable to explain) was why it overcharged. My S' 12V battery died as well (around the same time too, IIRC), but it was dead because the DC-DC converter failed and stopped charging it. Overcharging is a much more serious situation from my perspective.

 

[Evoforce]

I don't care much about the failing 12V. What did concern me (and they were unable to explain) was why it overcharged. My S' 12V battery died as well (around the same time too, IIRC), but it was dead because the DC-DC converter failed and stopped charging it. Overcharging is a much more serious situation from my perspective.

True, and it can happen with any lead acid battery in any type of vehicle or even solar backup batteries etc. A dumb charger will try to maintain the battery at a specified overall charge. If one or more cells are weak or dead, it will still try to maintain (overall battery/pack) voltage thus overcharging the good cells causing them to gas.

 

[Evoforce]

Which I failed to add is what an alternator can also do as a dumb charger on a petrol vehicle. About the only way to solve that is using a BMS on the 12 volt to manage the cells.

 

[gmtom1]

It seems that Tesla's OEM battery supplier needs to improve their QC, but it's also a design issue. I would guess that most 12V batteries don't have to deal with the high loads that Tesla puts on their batteries from running all the systems whenever the car is off.

 

[Evoforce]

It seems that Tesla's OEM battery supplier needs to improve their QC, but it's also a design issue. I would guess that most 12V batteries don't have to deal with the high loads that Tesla puts on their batteries from running all the systems whenever the car is off.

That is why the correct lithium battery shines in this application. It will be a good day when they completely eliminate the 12 volt out of the system.

 

[jjgunn]

What is this 12v battery used for? Cooling system & Auto-Presenting doors? Anything else?

 

[Peteski]

What is this 12v battery used for? Cooling system & Auto-Presenting doors? Anything else?

Since the automotive electronics world is universally 12V, I would imagine the 12V battery powers just about everything on a Tesla except the drive motors e.g. central locking, lighting, seats, heating/aircon, computers, displays, horn, music, etc, etc. It's also used to switch the high voltage system on/off. Without the 12V battery, the car would be a dead brick when the HV system was powered down.

 

[Evoforce]

Since the automotive electronics world is universally 12V, I would imagine the 12V battery powers just about everything on a Tesla except the drive motors e.g. central locking, lighting, seats, heating/aircon, computers, displays, horn, music, etc, etc. It's also used to switch the high voltage system on/off. Without the 12V battery, the car would be a dead brick when the HV system was powered down.

Yes, that is true but all you need to do is step down the HV battery to 12 volt to manage those circuits. I also do this on my higher voltage bicycles and lawn equipment.