Update on replacing OEM 12v lead-acid battery with lithium?

[Pianewman]

There are a few threads on this, but I couldn't find a definitive answer.

I purchased an Ohmmu battery 18 months ago, but returned it after learning of incompatability with the Tesla Y

Is anyone aware of a 12v lithium battery that works consistently in a 2020-2021 MY? Is there still the potential for software issues?

Thanks.

 

[jjrandorin]

I havent seen a lot of negative feedback about the mountain pass performance aftermarket one, but yes, there is absolutely, positively, 100000% still the potential for software issues, as I have not seen anything indicating that there is a 100% fix. The active "ohmmu" thread is still going, still with no 100% resolution, and various battery revisions later its still "I think it might work this time".

Longer term Ohmmu experiences?

np4nd4, post: 7851191, member: 153664"] I have installed the new battery with heating element since 3 weeks without any battery warnings but the car is idling most of the time and doesn't want to get in to sleep mode. I didn't drive since 3 days and doesn't wake the car. I didn't have this...

teslamotorsclub.com

I cant understand what the fuss is about, myself, since the lead acid battery is less than $100 at a service center, but people are still want to do this aftermarket since OEM isnt offered.

 

[MountainRatMat]

I cant understand what the fuss is about, myself, since the lead acid battery is less than $100 at a service center, but people are still want to do this aftermarket since OEM isnt offered.

lead acid battery can leave you stranded, it is a very short window (if any) from when you get warnings of a dead battery to an actual dead battery. I got some error codes on my way home one evening and the next morning my car would not move. Mobile service was quick but I was also "stranded" at home.

 

[jjrandorin]

lead acid battery can leave you stranded, it is a very short window (if any) from when you get warnings of a dead battery to an actual dead battery. I got some error codes on my way home one evening and the next morning my car would not move. Mobile service was quick but I was also "stranded" at home.

Sure, I get that part, thats the same as any other regular ICE vehicle. I have been "stranded' at home with at least a couple of the BMWs I have had, as well as a nissan maxima, a datsun B210 (my first car!), a ford taurus, etc.

Its still not worth it in this case to me, since the flip side of that with these aftermarket batteries is Tesla changes some charging algorithm, and now the battery throws codes all the time (pretty much the entire history of the ohmmu battery in model 3s).

 

[Cce32]

I was happy with my Ohmmu purchase, it is considerably lighter, will last longer and has the potential to let the audio system perform better.
Yes I had to do a few resets over the years on the original model but they also just sent me the latest version for free so they are a stand up company.

 

[zroger73]

DO NOT BUY Ohmmu!

If you have one, GET IT OUT before it damages your car or catches fire!

Use ONLY a 12-volt lead acid battery that the car was designed for.

 

[Ostrichsak]

I was happy with my Ohmmu purchase, it is considerably lighter, will last longer and has the potential to let the audio system perform better.
Yes I had to do a few resets over the years on the original model but they also just sent me the latest version for free so they are a stand up company.

Most of this is false. Sounds like someone bought the snake oil that Ohmmu sells.

Do a search of this forum is you want more details. You'll likely find more info than you could ever want on why Ohmmu is bad news for Teslas.

You couldn't pay me to install an Ohmmu into my Teslas.

 

[jcanoe]

My 2020 LRMY still has the original Hankook Atlas lead-acid battery 12V. I test the 12V battery every 3 months, so far the 12V is OK.

When at home my Model Y is parked inside my garage, enters Sleep mode. Should the 12V battery fail to wake up my Model Y from Sleep mode I have a portable jump starter to power up the Tesla Model Y, then the power conversion system (PCS) would take over and provide power for the Tesla Model Y's low voltage systems.

When parked away from home I usually leave Sentry mode enabled. Much of this time my Model Y is charging using a public Level 2 charging station. My Tesla Model Y remains in Standby mode during the time that Sentry mode is enabled and while charging. It is unlikely that a failing 12V battery would prevent me from unlocking the Model Y and starting to drive.

If the 12V battery fails within the remainder of the 4 year standard warranty period I will contact Tesla Service to schedule a replacement of the 12V battery under the warranty. If the 12V battery lasts beyond the 4 year warranty period I will schedule a replacement of the 12V battery once I decide how much longer I will continue to own my 2020 LRMY.

Sometimes I carry a 9V battery in my pocket as insurance in case the 12V battery fails. The 9V battery would enable me to release, open the frunk. I store the jump starter in the frunk storage bin so it can be accessible if needed. Even the smallest capacity jump starter (estimate cost: $50 US) would be sufficient to power the Tesla Model Y's 12V systems for ~10 seconds, until the PCS begins providing 12V power.

 

[Pianewman]

All good answers, and I like jcanoe's solution to mitigate risk when on the road.

TX heat kills lead acid batteries, so I proactively replaced my OEM with OEM battery at around 40k miles, IIRC. My road trips traverse desolate areas...west TX, NE NM, OK, even between FW and FL, across LA, service centers are few and far between.

 

[ucmndd]

lead acid battery can leave you stranded

Read around for stories about Tesla LV lithium batteries leaving people stranded if this is a concern... by all accounts the failure mode is way worse and significantly more expensive to address.

TX heat kills lead acid batteries

Lithium battery degradation is just as, if not more so, affected by high heat. It's the #1 factor in calendar aging.

Just don't do it. Especially the ohmmu junk.

 

[MountainRatMat]

Sure, I get that part, thats the same as any other regular ICE vehicle. I have been "stranded' at home with at least a couple of the BMWs I have had, as well as a nissan maxima, a datsun B210 (my first car!), a ford taurus, etc.

Its still not worth it in this case to me, since the flip side of that with these aftermarket batteries is Tesla changes some charging algorithm, and now the battery throws codes all the time (pretty much the entire history of the ohmmu battery in model 3s).

100% agree about not using aftermarket.

From my experience ICE gives you more warning than an EV that the 12V battery is about to die.

 

[Rocky_H]

From my experience ICE gives you more warning than an EV that the 12V battery is about to die.

Huh. I've never had a gas car that had the capability of giving any kind of warning that the 12V was going bad. It just doesn't work one day. Maybe I wasn't buying fancy enough cars before.

 

[MountainRatMat]

E

Huh. I've never had a gas car that had the capability of giving any kind of warning that the 12V was going bad. It just doesn't work one day. Maybe I wasn't buying fancy enough cars before.

Every ICE I've had the starter would get more difficult to turn over, especially when cold. Also, you can jump an ICE, you can't jump an EV with a dead 12V battery so you can always drive down to the auto parts store and just swap out the battery. Not the same in an EV...or at least a Tesla.

 

[zroger73]

Also, you can jump an ICE, you can't jump an EV with a dead 12V battery so you can always drive down to the auto parts store and just swap out the battery. Not the same in an EV...or at least a Tesla.

Sure, you can! Tesla provides jump starting instructions in the owner's manual.

https://www.tesla.com/ownersmanual/modely/en_us/GUID-3567D5F4-A5F4-4323-8BE0-023D5438FFC6.html

They also provide low-voltage battery replacement instructions.

Model Y Do It Yourself | Tesla

service.tesla.com

 

[MountainRatMat]

Sure, you can! Tesla provides jump starting instructions in the owner's manual.

https://www.tesla.com/ownersmanual/modely/en_us/GUID-3567D5F4-A5F4-4323-8BE0-023D5438FFC6.html

They also provide low-voltage battery replacement instructions.

Model Y Do It Yourself | Tesla

service.tesla.com

Yes you can jump it but does the car work with a dead 12V battery after the jumper cables are removed? I honestly don't know the answer to this question. When my 12V battery went it was a stinky mess and there was no warning. "Stranded" in my own garage until mobile service showed up and replaced the battery.

 

[zroger73]

Yes. The PCS will supply power to the low-voltage bus, but if you allow the vehicle to go to sleep, you'll need to jump start it again.

 

[CaseyL]

Yes. The PCS will supply power to the low-voltage bus, but if you allow the vehicle to go to sleep, you'll need to jump start it again.

Turn on Sentry Mode to keep it awake?

 

[zroger73]

Sentry Mode or keep the climate control on.

 

[ucmndd]

Yes you can jump it but does the car work with a dead 12V battery after the jumper cables are removed?

Yep. Just like an ICE car runs on the alternator once it's started, Tesla runs off the HV battery via the DC/DC converter in the Power Conversion System.

 

[Ostrichsak]

E

Every ICE I've had the starter would get more difficult to turn over, especially when cold. Also, you can jump an ICE, you can't jump an EV with a dead 12V battery so you can always drive down to the auto parts store and just swap out the battery. Not the same in an EV...or at least a Tesla.

You know how I know you live in California?

Try living in the Midwest. There is no "advance warning" on a 12v battery on it's way out. You typically find out one morning when you go out to start your car when the weather is below 0 degrees to find it won't turn over. That's a typical "warning" on a 12v battery failure in all parts of the country other than Southern California. Speaking first hand from owning literally dozens of ICE cars up until about 6 or so years ago... this sucks.

Conversely, I've owned 8 Teslas now and a few have had the 12v battery fail (factory unit, most replaced in the ~80k range) and every single one of them has told me at least weeks in advance based on when I've had them replaced. Who knows, from reports I've read and even words from Tesla Technicians mouths... likely months before I'd actually get full failure that left me stranded somewhere.

Personally, I know which of those two scenarios I prefer.

Tesla (unlike every other ICE car I've ever heard of) actually has a system to monitor voltage and detect when the battery is on it's way out long before it actually fails, in most cases. Rarely do 12v batteries fail instantly but it can happen and there's no detection for these types of failure in any forward propulsion type.

When it comes to low voltage, there's no question that Teslas are better than every other ICE car made. This is also due in large part that the requirements are nill for a 12v battery in a Tesla. It needs only to operate the contacts, screens, stereo, blinkers, wipers and all other accessories. There's no demand for massive amperage to physically turn over an internal combustion engine which takes massive amounts of juice. Especially in cold weather. Hence why CCW are the primary metric that separate batteries. CCW don't even apply to Teslas. It's meaningless.

This should tell you all you know and is also a massive reason why Ohmmu is worthless despite their marketing efforts. Your blinkers will not work better with an Ohmmu so don't be the gullible person who falls for their marketing BS because none of it applies to Teslas.