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12 Volt Replacement Battery- MF, EFB, AGM or Lion?

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I have been researching various replacement batteries for the Model 3 that had the AtlasBX MF 85B24LS (MF51-650). It appears the factory AtlasBX, while very powerful starting amps (625 CCA) is just a lead acid flooded battery that is maintenance free. It seems like Tesla just put the strongest Lead acid starting battery they could find. But the Tesla's don't need a heavy load of cranking amps but available amperage over the variable charge status of the battery. This may explain why Tesla went with Lion as the new battery installs. Unfortunately the Tesla Lion has different connectors and isn't set up for a retrofit.

It looks like batteries with a BCI of 51R are suitable for size as a replacement. It also seems an EFB or AGM battery would be suitable than the factory MF battery since they are designed for frequent deeper charge cycles.

I know right now the Ohmmu Lion is going through a design change and worked quite well until now, but has anyone tried an EFB battery? I've seen on a post of a user with an O'Reilly AGM 51R (51RPLT) and used it for multiple years and over 50K miles and many software updates including more recent with no issues.

So what would be the choice - Factory AtlasBX again, EFB, AGM or wait for the Ohmmu replacement?
 
The OEM batteries were problematic and am looking for a replacement rather than waiting for a failure message.
There's no problem if the failure message is timely and accurate. The problem has been 12v battery failures, without warning, or failures almost immediately after a warning. Those can leave you stranded. Prior Teslas seemed to have a 2-week window after warning, leaving plenty of time to schedule a mobile replacement.

Having said that, just anecdotally reading these 12v battery threads, there seems to be fewer of the random failures without warning. It's possible that the reported software updates to address this issue has actually had some benefit. If that is actually the case, then the need to pro-actively replace a battery is eliminated.
 
out of warranty (4yrs and/or 50k miles) I would definitely proactively replace the 12V. That's acceptable mileage/ age for a new 12V battery.
Short of extreme scenarios - I would expect the 12V battery to last at least that long. and if not - have Tesla fix it on their dime ... maybe that will drive some engineering focus on solving something as mundane as a 12V battery (my guess is that with new cars and lithium 12V now it has been solved).

ICE cars have very high temperatures under the hood during operation and after parking - whereas EVs don't. So our 12V battery in the Tesla is exposed to less high temperatures and shouldn't crap out after just 2yrs.

I spent some $ on a battery powered NOCO jump starter and hope that will do should the 12V battery fail under less ideal circumstances. When traveling out of town I have sentry mode always on - so the car should never go to sleep.
 
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The OEM batteries were problematic
Stop using absolute statements like that. It's false because you stated it so absolutely as ALL of them being problematic.
There's no problem if the failure message is timely and accurate. The problem has been 12v battery failures, without warning, or failures almost immediately after a warning. Those can leave you stranded. Prior Teslas seemed to have a 2-week window after warning, leaving plenty of time to schedule a mobile replacement.
I have an old 2014 Model S. It has behaved exactly as it is supposed to through multiple 12V batteries. I get the warning notice, I schedule service, they get it done within several days, and it's fine. Each of those 12V batteries has lasted about 3.5 years, which is pretty acceptable.

I do agree that it seems the older cars handled this a lot better. The 3 and Y seem to be having a lot more problems with not giving the warning notices.
 
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Stop using absolute statements like that. It's false because you stated it so absolutely as ALL of them being problematic.

I have an old 2014 Model S. It has behaved exactly as it is supposed to through multiple 12V batteries. I get the warning notice, I schedule service, they get it done within several days, and it's fine. Each of those 12V batteries has lasted about 3.5 years, which is pretty acceptable.

I do agree that it seems the older cars handled this a lot better. The 3 and Y seem to be having a lot more problems with not giving the warning notices.
My reference to problematic 12 volt batteries was for the Model 3. This was published in the Model 3 forum. I have no knowledge of Model S.
 
The original equipment battery is $85. What problem are you trying to solve by not buying one of those? There is no option currently that saves money over the OEM that I am aware of.
Tesla has sent mobile service to my home several times to fix my 3 or Y but now that I'm getting "replace low voltage battery" message, they want me to travel 260 miles one way to service center in 90 degree plus heat (I'm 74) and suggested that if it dies on the way, to call tow truck (2018 model 3 and out of warranty). I'll gladly pay more for a 3rd party battery. I just cannot find one.
 
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Tesla has sent mobile service to my home several times to fix my 3 or Y but now that I'm getting "replace low voltage battery" message, they want me to travel 260 miles one way to service center in 90 degree plus heat (I'm 74) and suggested that if it dies on the way, to call tow truck (2018 model 3 and out of warranty). I'll gladly pay more for a 3rd party battery. I just cannot find one.
That's nuts. I'd schedule the service, but hope they change it to mobile service. I'd also just go check SamsClub or Walmart for a 51R. My local Sams sells it for $115, but just $85 when it's on sale. Duracell brand. Even if you have to pay for it, it's way cheaper than wasting your time to drive over 500 miles roundtrip.
 
Tesla has sent mobile service to my home several times to fix my 3 or Y but now that I'm getting "replace low voltage battery" message, they want me to travel 260 miles one way to service center in 90 degree plus heat (I'm 74) and suggested that if it dies on the way, to call tow truck (2018 model 3 and out of warranty). I'll gladly pay more for a 3rd party battery.

Local auto parts store 51R battery at least 33 AH according to manual (greater is OK as AtlassBX battery is 45Ah), Use a 10 mm socket. Good instructions on Ohmmu.com site on how to change battery with pictures/Video. Takes about 15 minutes.
 
Great thread. Can you purchase a battery from AutoZone or does Tesla require a specific 12 volt battery?
Yes you can, and I did. The Tesla OEM battery is the cheapest at $85 and my original was still working well after 5 years and 107,000 miles.

I decided to replace it with this one from AutoZone (https://www.autozone.com/batteries-...ry-51r-efb-group-size-51r-500-cca/1070704_0_0) to see if it would increase the time my car stays asleep before charging it back up again. It's sealed like the original and had the vent hose holes. Just transfer the plug from one vent hole from the original battery and plug the house into the other hole. Only things to consider are that it is VERY expensive at $235 and that it is a little bit shorter than the original battery. Because it is shorter, I had to use a small piece of high density foam mat under the battery clamp to hold it down snuggly.

A cheaper battery that will fit perfectly can be bought at Menards. This is if you are not near a Tesla service center and you live in an area that has Menards stores. It is also the right specs, has the vent holes, and is only $114. https://www.menards.com/main/tools/...609692/p-4364363665502554-c-1516819218414.htm
 
You can also go to Advance Auto (may need to order not all stores carry in stock) a Model 3/Y Diehard specific model. It's AGM not Flooded lead acid and mine came with the adapter for the vent already installed.

Why go AGM? I have used AGM batteries on ICE cars but that was because I wanted better cold cranking power, better resistance to heat and vibration. None of those should be a concern with an EV.
Also, isn’t the internal resistance lower on AGM batteries requiring different charging parameters? Seems like the change to AGM would require some sort of “registration” between the battery and the car’s charging circuit.