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Tesla mobile service replaced 12V lead acid battery

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I believe that there is some sort of issue with the lead-acid batteries (or possibly the charging system?). I've never had a new vehicle eat through batteries as quickly as my Model Y does. The original battery lasted almost 2 years, which I think was good/standard (1st battery was replaced under warranty). From there the battery longevity has taken a dive. The replacement battery lasted about 1.5 weeks (2nd battery also replaced under warranty). The third battery is now dying and needs to be replaced (I assume it will be under warranty, it lasted 5 months). I'm now waiting for battery #4...and the car is just over two years old. No "accessories" on the car that use power, it's always garaged, and driven somewhat regularly, not every day but a few times a week at least (less than 19k miles).
It seems to be a general problem for all modern EVs (and maybe modern cars in general). When old-fashioned cars are off, they are OFF. There's virtually nothing drawing on the 12v. Modern cars have entertainment systems, cellular modems, security systems, preconditioning, etc... all draining the 12v during the "off" time. 12v lead-acid batteries like to be kept at a high level of charge pretty much all the time. The more they are cycled from high to low, the shorter their lifespan. Also, the electronics in these cars can get into weird states when the 12v battery is drawn down to very low voltages (think 6-7v), so they may refuse to start or just have odd symptoms when that happens.

And if the car has some kind of fault (or 3rd party add-on) that drains it faster than expected, the car may not succeed in keeping the charge up on the battery properly...and it doesn't take many episodes of being over-drained to ruin a lead acid car battery.

I've seen similar complaints about 12v battery problems on the LEAF and RAV4EV forums.

That's why Tesla has finally transitioned to a Lithium battery. They don't mind the cycling nearly as much, in fact they like that better than being kept at max charge all the time. Also, that 15v Lithium battery is likely putting out a decent voltage even when almost completely drained.
 
I would think that the car would be able to float the 12v battery either from being charged (or connected to the charger) or directly from the HV battery. There are plenty of electronics on board to be able to monitor the charge level and "trickle charge" the 12v as needed. I get that batteries wear down, I have the same issue with my motorcycles (all of which I keep on trickle chargers), but it feels like sometimes the system works great and other times it just barely works. I'm certainly not suggesting this is a Tesla only issue.
 
I believe that there is some sort of issue with the lead-acid batteries (or possibly the charging system?). I've never had a new vehicle eat through batteries as quickly as my Model Y does. The original battery lasted almost 2 years, which I think was good/standard (1st battery was replaced under warranty). From there the battery longevity has taken a dive. The replacement battery lasted about 1.5 weeks (2nd battery also replaced under warranty). The third battery is now dying and needs to be replaced (I assume it will be under warranty, it lasted 5 months). I'm now waiting for battery #4...and the car is just over two years old. No "accessories" on the car that use power, it's always garaged, and driven somewhat regularly, not every day but a few times a week at least (less than 19k miles).
On the outside of Lead Acid or AGM battery it said charge max at 14.4 V. when I first have tesla model 3. I use the Multimeter and the digital plug in cigarrete lighter both said it charge over 14.6 or 14.75 most of the time. I trade in model 3 that has so much problems all over. Wheel bearing sound, seat sound squirt every time get in or out or make a move on the seat. door handles, ... knock sound at pot holes made loud sound during charging etc they . for model Y cost me more because I bought the M3 65,204 2018 with Silver color + Auto pilot add on. Trade in lost 30,204. they buy back 35,000. Tesla is not cheap to fix any parts and tesla Kearney Mesa in San Diego, CA service is very bad, damage my MY during replace the High Voltage battery at 1200 miles but refuse to fix it.

The 12v problems is that it over charge the battery, that's why it go bad quickly. I report this but they do not do anything. They could of limited the float charge down to 14v or 14.2v and that would help the battery last much longer. The lifepo4 battery is 3.65 v max right? so 3.65 x 4 =14.6 very close but keep the lifepo4 at this high would make the lifepo4 shorten life too. 3.5v lifepo4 is the best. it would last 10-15 years. if Tesla make 4x 3.7v which is 4.2v would be ok with their problem of the charger system but if 12v /4 = 3. The milliamp is low and voltage high still not good. So the best is program it to limited charge to 14.2v would be best. But they not do it. I report this few times to tesla website or contact email on their website. Not sure if they can program it to lower the voltage charge or they have to change the parts....
 
I had Tesla mobile service replace my 12V lead-acid battery. Scheduling was through the Tesla App. I selected a day and timespan (noon to 5pm). He arrived a few minutes after noon.

It literally took him 4 minutes to do the entire process:
  1. I opened the frunk
  2. I opened driver's door (just in case)
  3. I turned off the air conditioning
  4. He removed the full-width wide plastic panel covering lead acid battery
  5. Using a power driver, he loosened two bolts
  6. Removed the old 12V lead acid battery (Atlas)
  7. Installed a new 12V lead acid battery (Atlas; looks the same as the old one)
  8. Put back the plastic panel
I'm mentioning this because I thought they needed to disconnect the 400V orange connector under the rear seat. But he didn't; and the car seems happy with the new battery.

21,000 miles. Total cost to me was $0
:)

The hilariously funny thing is that he didn't come in a Tesla mobile (ICE) service van. He said it had broken down, so he arrived in his personal Model S. He pulled my new battery out of his trunk and got right to work.

This was my first experience with Tesla mobile service. Gold star 🏆 and absolutely fantastic in not needing to take my car to a shop; especially since I live out in the country about an hour from the nearest Tesla Service Center.

Scott

PS The Central Valley eats lead acid batteries; it was 118 last week. My ICE lead acid batteries only last for 3 years, so I don't fault the Tesla. This hot dry environment is just hard on lead acid batteries.

--

MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021
My experience, at 22000 miles was very similar. Requested new battery through app, expecting to pay for it. Done at no charge. From what the tech told me, the battery did not test well to them, and had prevented the a/c system OTA update/recall, which he did in my driveway.
 
I have never seen a label affixed to the Tesla Model Y 12V battery that indicates maximum charging voltage. Can you provide a photo?

The 12V battery used in 2020 - 2021 Tesla Model Y is a sealed flooded lead-acid battery. This battery is sealed but is not an AGM battery.

If the 12V battery fails within the first 4 years or 50,000 miles of ownership Tesla will replace the 12V battery.

I don't understand the rest of your post. If you have an issue with Tesla Service damaging your Tesla Model Y you should invoke the arbitration clause of the purchase agreement or consult an attorney.
 
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I had Tesla mobile service replace my 12V lead-acid battery. Scheduling was through the Tesla App. I selected a day and timespan (noon to 5pm). He arrived a few minutes after noon.

It literally took him 4 minutes to do the entire process:
  1. I opened the frunk
  2. I opened driver's door (just in case)
  3. I turned off the air conditioning
  4. He removed the full-width wide plastic panel covering lead acid battery
  5. Using a power driver, he loosened two bolts
  6. Removed the old 12V lead acid battery (Atlas)
  7. Installed a new 12V lead acid battery (Atlas; looks the same as the old one)
  8. Put back the plastic panel
I'm mentioning this because I thought they needed to disconnect the 400V orange connector under the rear seat. But he didn't; and the car seems happy with the new battery.

21,000 miles. Total cost to me was $0
:)

The hilariously funny thing is that he didn't come in a Tesla mobile (ICE) service van. He said it had broken down, so he arrived in his personal Model S. He pulled my new battery out of his trunk and got right to work.

This was my first experience with Tesla mobile service. Gold star 🏆 and absolutely fantastic in not needing to take my car to a shop; especially since I live out in the country about an hour from the nearest Tesla Service Center.

Scott

PS The Central Valley eats lead acid batteries; it was 118 last week. My ICE lead acid batteries only last for 3 years, so I don't fault the Tesla. This hot dry environment is just hard on lead acid batteries.

--

MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021
Yes parking mine at the airport for over a week, hot sun ( uncovered) ruined my aux 12 volt. FYI, a 2019 model under 6000 miles). I would imagine extreme cold temperatures don’t do the battery any good too?
 
Yes parking mine at the airport for over a week, hot sun ( uncovered) ruined my aux 12 volt. FYI, a 2019 model under 6000 miles). I would imagine extreme cold temperatures don’t do the battery any good too?
Cold temperatures don't harm the lead acid battery as long as it is charged. Cold will reduce the cold cranking amps, but that doesn't really affect a Tesla because there is no starter motor to turn. The vast majority of early failures that I've read about happen in really hot areas.
 
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