The Ohmmu replacement 12V battery for Tesla vehicles uses LiFePO4 chemistry.
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12V battery replacement: Tesla Li-ion
- Thread starter mark95476
- Start date
NY_Rob
Member
^ probably one reason it's more expensive than the Li-Ion battery available from the Tesla parts catalog.
Tesla went from having a 12V battery that is not easy to get to in the Model S, Model X to a 12V battery that is easy to access in the Model 3, Model Y. Now that Tesla has added Bioweapon Defense HEPA filtration to the Model Y you will have to remove the HEPA filter, filter housing to access the 12V battery in the Model Y. 
iwannam3
Active Member
Maybe the new Li 12v will be in Texas and Berlin production of 3 & Y and should last a long time so location is not so critical. Still need to have a accessible 12V power cable loop for cutting to de-energize main battery.Tesla went from having a 12V battery that is not easy to get to in the Model S, Model X to a 12V battery that is easy to access in the Model 3, Model Y. Now that Tesla has added Bioweapon Defense HEPA filtration to the Model Y you will have to remove the HEPA filter, filter housing to access the 12V battery in the Model Y.
I tried to access parts info but it requires me to register as a repair shop with insurance, etc. What am I missing? I can work on my car and would like to be able to purchase parts such as door handles. Also - I happened to note that the battery now offered indicates "AGM."
I tried this but can't see the prices, it seems to require me to register as a repair shop with insurance, etc. What am I missing? I'd like to be able to purchase parts such as door handles. Also - I happened to notice that the battery in the parts catalog is described as "AGM."
I have only logged in to search the parts catalog using my Tesla account Id and Password. I have never attempted to purchase parts from Tesla.
The absorbent glass mat (AGM) description on the 12V battery is an interesting development. An AGM battery would potentially be a good choice as a replacement for the current 12V sealed - maintenance free (MF) flooded lead-acid battery.
My 2017 Chevrolet Volt used an AGM 12V battery. Based on the feedback from Gen1 and Gen2 Volt owners the 12V AGM batteries can sometimes last beyond 5 years in the Volt. (I replaced the 12V AGM battery in my Volt at 3 years when my battery tester indicated it should be replaced.) One difference is that AGM batteries cost more to purchase than a similarly sized conventional flooded lead-acid battery. Even with a higher replacement cost it may be that Tesla has found a source for a 12V AGM battery for the Model Y (Model 3?) and may be changing from the current 12V battery. From the outside an AGM type battery and a maintenance free (MF) type battery look very similar. Only the battery markings would tell them apart.
iwannam3
Active Member
The battery I bought from Tesla is not AGM, or sealed. There is a vent on the top driver side of the battery that is connected to a hose, My Mini and Prius was AGM because they were in the passenger compartment. Here is the parts catalog entry for the battery, DOES NOT say AGM, just below it is the part number for the vent hose.
| ASY,12V BATT AND VENT PLUG,M3 | 1129182-00-B |
| 12V, BATTERY VENT HOSE ASSY | 1110937-00-A |
NY_Rob
Member
For hobbyist's the new Plaid 12v primary battery is just 8 Li-ion 3.6v cells in a 2P/4S configuration with a BMS. They should have been using this setup for years now.
Part 2: It's sourced from CATL who provide a lot of batteries for Asian/European Tesla 3/Ys.
Reviving this old thread since there are now accounts of these batteries making it into YS and 3s.
I’ve listened to both engineerix vids and reviewed the data. The following jumped out at me. The 12V battery can function above -20C and charge above -10C and there are no built in heater... Here in Canada, we often wake up to sub -20C temps... how is that going to work? It is possible that by keeping enough loading on it, it will keep warm enough to keep it above -10C. But that will cause the PCS to wake frequently causing a significant vampire drain since the li-ion has so little capacity. In other words, you will not want your car to sleep too long bellow -10C without being plugged in...
Anyone have real life experience to share on this?
I’ve listened to both engineerix vids and reviewed the data. The following jumped out at me. The 12V battery can function above -20C and charge above -10C and there are no built in heater... Here in Canada, we often wake up to sub -20C temps... how is that going to work? It is possible that by keeping enough loading on it, it will keep warm enough to keep it above -10C. But that will cause the PCS to wake frequently causing a significant vampire drain since the li-ion has so little capacity. In other words, you will not want your car to sleep too long bellow -10C without being plugged in...
Anyone have real life experience to share on this?
thesmokingman
Active Member
You should read the user experiences in the model 3 subforum. On some firmware the car will firewall the battery and there is no fix. Is that a chance you would take on? Yea the sub zero temp abilities are interesting though I don't know if it is any better than the regular battery but...
I’m expecting the Li-Ion to be worse than lead acid in cold. Li-ion you plain can’t charge bellow a certain temp without destroying it. Lead acid you can use/charge at any temp.
Midnightsun
Active Member
Problem with Lithium is it does no like the cold. They get heated by commands from the BMS if so equipped/required. No different than your Tesla main battery. The Lithium will work great in the Tesla as the main battery will take care of the 12v side providing heat and/or charge as required.
dbldwn02
Active Member
Good info here. I'm in the middle of replacing my 12V just because I was already digging around the car replacing other stuff, like the onboard charger. I'm looking for a decent aftermarket 12V. Batteries+ had a Duracell SLAA12-35C but the posts weren't reversed. Other than the posts reversal, it looked like it would work. I don't want to order online just because I'm impatient.
Anyone have any options other than the $165 one on Ebay?
Anyone have any options other than the $165 one on Ebay?
I’d go with the Tesla one for $85 and put a calendar reminder to change it at 24 months.
dbldwn02
Active Member
thesmokingman
Active Member
The cold performance isn't even the big issue. The next firmware update could make the Ohmmu useless meaning you're car gets disabled, or prevent an update from completing. Granted a small percentage gets affected. There's no choice but to take their word on it, but it does happen. That's kind of a big risk to take with a huge huge cost attached to it. That's why I suggested reading the model 3 forum before...
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