So while driving with the tow truck driver to get my flat tire repaired (4 flats in 16 months, all rear tires, that's another story) I got to hear interesting/crazy stories about why Teslas need to be towed. He said a biggie is the "small battery" going dead making the vehicle inoperable because the computer is dead. He said if the vehicle is plugged in but not operated for weeks, this small battery does not get recharged and can fully discharge. So the big battery for the motor is fine but the small battery is not, and he gets called out to tow the vehicle to the nearest Tesla service center to recharge the small battery and reprogram the vehicle doors, etc. He said it happens in the mountains where he works, when the weather is cold and people leave their vehicles sitting for weeks without using them, even though again they are plugged in. Anybody know if this is true or fiction?? If true I'll need to think about this next time I take a long trip away from home.
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"Small battery" fully discharges in a month or so if the vehicle is not operated?
- Thread starter newcarbuyer123
- Start date
andaconda
Active Member
Sounds like bull puckey to me. The 'big' battery will wake up occasionally and charge the 12v battery.
boulder.dude
Member
EVer Hopeful
Active Member
On a different note, I wonder how an ICE vehicle would perform if "not operated for weeks"
(although I know that's not what you were getting at)
(although I know that's not what you were getting at)
Not going to talk with your tow truck driver for help understanding how Tesla vehicles maintain the 12V battery. He might be knowledge on how to get the vehicle up on a flatbed but beyond that not so much.
That is utter hose &*$#. He is taking one thing he does know, but is then making a totally false, unfounded conclusion about the cause of it.
Sure, there have been a pretty high number of 12V batteries fail in Tesla cars. They use them differently than gas cars do, which is a pretty high rate of wear on them, by draining them down and refilling often. The cars absolutely do monitor the 12V batteries and do recharge them frequently, whether the car is plugged in or not!! The car should be able to detect when that battery is getting weak and show you a warning on the screen that it needs replacing, and then you should have a few weeks or a month to get it replaced before it really dies. My old Model S has done that perfectly well for 8 years now, with each 12V battery lasting about 3.5 years. But that has been a mixed bag for a lot of people, where sometimes they don't get any warning, or the warning comes too late, just a day or two before it fails.
andaconda
Active Member
I for one have had good results with my 1983 VW Pickup parked in my garage. I go 4~5 months without charging it, and it fires right up. I have replaced it on the average of once every 10 years! FWIW the battery in my "Y" has a "Hankook" label on it.
Older vehicles do not have all of the modern electronics including alarm systems, radios, Wi-Fi, OnStar etc. These components use a small amount of power when the vehicle is parked. Manufacturers plan on the vehicle being parked for a reasonable time, perhaps 30 to 60 days; beyond that the 12V battery should be disconnected or else a trickle charger should be attached to the 12V battery.
He's not "my" tow truck driver, he's the one dispatched by Tesla .......Yeah I should have just told him he's full of ship, and has no idea why the small batteries go dead and stick to towing. The point of the thread was, why would a *plugged in* Tesla go dead simply because it is not being operated.
damonbrodie
Member
James May had it happen on his MS:
insideevs.com
James May's Tesla Model S Dies, He Gets Locked Out
Automotive YouTube channel DriveTribe posted a video about how James May got his Tesla Model S running again after one of its batteries died.
insideevs.com
Not sure that's true. Here in the DFW region, many have had the warning, then total 12V battery failure within a day or two.
I think the best advice would be, if you get a 12V battery warning, get it serviced ASAP. I think 12V battery replacement at the SC gets priority, at least that's what I've read about here.
Huh? Why would you say that what I said is not true, but then repeat EXACTLY the same thing I said?
It can happen that the 12V battery in the Tesla vehicle fails, won't hold a charge. This can happen whether or not the Tesla is left plugged in. As designed, when the 12V battery used in the Tesla vehicle starts to fail the Tesla vehicle will display a warning on the Tesla screen to notify the owner/operator that the 12V battery requires service. Sometimes the 12V battery fails with no warning.
The 12V battery is covered under the 48 month new vehicle warranty. Tesla Mobile Service (where available) will replace the failing/failed 12V battery. You can keep a 12V jump starter at home in case the 12V battery fails. The procedure for jump starting the Tesla vehicle is covered in the Tesla Model Y Owner's Manual.
No, that post is too old now, and I can't edit it.
Confusing?
It says two different things on purpose, because it's explaining:
Here's what should happen, but sometimes what really happens is ________.
I thought that's a fairly clear thing to tell to people, and those are sometimes different things.
howardnj
Member
In 2019 I left my present 2016 Q70 Infiniti parked in the garage while on a 49 day cruise. It started right up after returning. This past summer the wife's 2019 Mercedes E Class wagon was parked in the garage for 10 weeks while we were away. It started right up upon our return. It is not unheard of for 12v lead acid batteries to have a weak cell even when new. How long have some of those batteries been sitting on a shelf? They should have a date code printed on a label on them. If they are not sealed and have vent caps the individual cells specific gravity can be checked with a battery hydrometer.
sleepydoc
Well-Known Member
We had a Saturn Ion many years ago that died in 2 weeks. Of course that was GM….
As has been said, all cars have a small parasitic draw to run the onboard computers. This will eventually drain the battery; how long depends on the battery, hardware and software. Well designed and programmed systems should last for several weeks. Not all systems are well designed and well. programmed, though.
norcalbowler94
Member
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