My "other coworker" mentioned above just got the 12v replacement notice warning. So now 4 out of 4 of us who got Model 3 AWD in fall of 2018 got the warning messages under 4 years. I think Tesla is replacing a LOT of 12V this summer LOL.
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"Proactive" 12v battery replacement - good idea or overkill?
- Thread starter joebruin77
- Start date
My "other coworker" mentioned above just got the 12v replacement notice warning. So now 4 out of 4 of us who got Model 3 AWD in fall of 2018 got the warning messages under 4 years. I think Tesla is replacing a LOT of 12V this summer LOL.
At least you got notified. The big issue is random failure where people get stranded out of the blue.
Mine failed last fall just shy of 3 years. No warning. Left the office and the door opened fine, plopped my computer bag on the passenger seat and noticed that the air hadn't started and the screen didn't light up. Tried button reset but nothing. Had to use the emergency release to get back out of the car and made the huge mistake of closing the door behind me. It wouldn't open up again. Called Tesla service and they sent a flatbed. The guy gets there and connects his jump battery to the leads behind the towhook and it initially wouldn't pop the frunk. Took a bit but I finally saw it showup in the app and was able to get it popped from there. He then pulled the cowling off and hooked up the jump battery to the 12v in the car. Still couldn't get the doors to open. Said that he had never had that happen before. So he had to wrestle the car onto the flatbed without being able to get inside of it. Luckily he was good at his job and the parking lot was fairly empty by then. By then my wife had come to pick me up & they had it ready by about 9:00 am the next day. I needed to pick it up right away, because as I said my computer was in the car.
I wish they could have just sent a ranger to replace it on the spot. I got a lot of comments from people that saw my "fancy" car loaded on the flatbed & had to explain that it was the 100 year old lead acid technology that failed. Everyone would have thought it was awesome if a ranger would have come and fixed it right there on the spot.
I wish they could have just sent a ranger to replace it on the spot. I got a lot of comments from people that saw my "fancy" car loaded on the flatbed & had to explain that it was the 100 year old lead acid technology that failed. Everyone would have thought it was awesome if a ranger would have come and fixed it right there on the spot.
Yep, before they updated the detection method last winter.
Still waiting for someone to point to this happening in the last 6 months.
None of this makes sense. The leads behind the towhook do not jump the car. They pop the frunk directly and have no connection to the rest of the car.
metroplex
Gearhead
For those that have the lead acid, is there an easy way to retrofit a lithium ion battery? Either the new CATL LFP or an aftermarket LFP?
andy.connor.e
Member
Not sure if its still relevant, but i picked up my 2018 in 2020 and have not replaced the battery. No idea if it was replaced prior. At the time it seemed to be a community consensus that it would either go back quickly or would last a while.
stopcrazypp
Well-Known Member
There are aftermarket LFP batteries like Ohmmu, but they need to play the cat and mouse game in terms of a BMS that is able to fool Tesla's BMS into thinking the attached battery is a good condition 12V lead acid. You can't just easily plop in a generic LFP 12V battery and expect it to work properly.
The custom CATL LFP pack Tesla is using in the newest cars is completely different (14.8V nominal) and the car side BMS is also completely different so is not going to be an easy retrofit.
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It's not LFP. It's standard NMC, which is why the nominal voltage is 15V. As an example of the impact, these cars use different wiper motors due to the different voltage. It's also way smaller in capacity (99Wh vs >400 for the Lead Acid), is locally managed, and is on the CAN bus. It's also unheated, so behavior in extended cold temps is unknown.
Which to be clear, is not the normal behavior of a BMS. To do this accurately, they would need to change the actual voltage the battery puts out, not just protect from under and over voltage.
Here's a big thread on an aftermarket LFP battery and the issues people have been having since Tesla improved their 12V managment:
Longer term Ohmmu experiences?
Hi Looking at possibly buying an Ohmmu lithium (LiFePO4) battery to replace the OEM one in my Model 3. The car is approx 18 months old and from what I can see from stats it has started waking up to top up the 12v battery every 24 hours, so I don’t think it’ll be too long before it says it needs...
teslamotorsclub.com
stopcrazypp
Well-Known Member
You are right, it's NMC. I presumed given it was CATL that it would be LFP like most packs, but it's not.
metroplex
Gearhead
It's probably my fault cause I might have referenced it as LFP. 'Sho 'Nuff, it's NMC. Are there any 2022s that wouldn't get this low-voltage battery? Maybe the early ones?
Tesla's New 12V Li-Ion Auxiliary Battery Has CATL Cells Inside
With the refreshed Model S/Model X, Tesla has switched from lead-acid to an all-new lithium-ion 12V auxiliary battery. Let's take a look.
insideevs.com
I wonder if tesla wpuld do some sort of upgrade bundle that includes the parts to fit the newer battery to the older cars.
Why? Would you really pay $2K to "upgrade" to a a small lithium battery?
If you are so worried, carry a spare 12V battery in the frunk, a 10mm wrench, and learn how to swap it yourself.
metroplex
Gearhead
Would a small 12V Li-Ion/LFP battery work? Like a Shorai LFP designed to replace a motorcycle battery? They're designed for about the same 12V charging profile according to the battery OEMs.
You need the battery itself. A new DC/DC (or "PCS"), new wiring harness, new windshield wiper motors, and who knows what else. Even if the parts were free, labor would not be trivial.
You can dig through the Tesla parts catalog and find everything that changed if you really care.
5 posts above yours is a link to a thread on a company that does that and the issues they are having because Tesla's charger throws errors with LFP batteries because the charger is very sophisticated and can/has changed with firmware updates.
stopcrazypp
Well-Known Member
It's both, from the very thread you linked:
"The PCS sits on top of the battery and controls AC and DC charging as well as supplying 12 VDC".
In this particular application you care mostly about the DC/DC portion as that is what handles a bulk of the 12V supply/charging. It is rare when you are charging from AC (some people never do if they rely exclusively on supercharging) and even then I'm not even sure if there is a direct 120/250V AC to 12V DC conversion in that case (as opposed to converting to ~400 VDC and then converting to 12VDC as normal).
It does both. It's the battery charger from L1/L2 AC grid sources, but it also converts the high voltage battery (which is DC) to "12V" which is also DC.
So it does a lot.
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