12V Battery Just Died - Total battery failure

[skraack]

I have a 2018 Tesla M3 LR, 45K miles 20 months old. We drive it a lot in the Florida Heat. We drove it last night with no problems. Just put it on the charger in garage at home, came out the next afternoon to go for a trip, and the car was Dead!! Electric doors not opening, lights fading in and out, computer tried to restart a couple times, but the windows on the drivers side went down to allow access to the emergency door latch so we could get in. After a little web investigation, quickly determined the 12V battery was dead, no electronics working. Not surprising in the Florida Heat, but too soon for a battery failure, IMHO. Even in my gas cars, I never have a battery last much more than 2 years in the extreme heat and heavy driving we do.

But this battery failure is unusual. We managed to get the frunk opened by putting a 12V battery to the wires behind the Tow Hook cover plate, which I broke while taking it out. (Another topic, have to replace that) With the Frunk open and the plastic cover off, we got a strong smell of SULFUR from the 12V battery area. Also the 12V battery was very HOT to touch. Made a decision to get it out of the car NOW!!! I pulled the main power disconnect under the rear right seat to be safe. Continued to remove the battery mount clamp, negative terminal, positive terminal and removed the battery.

After inspecting the battery, heat and smell was all coming from one side of the battery and I noticed a bulge in the side of the battery case.(See picture below) This battery has clearly had an internal plate failure. I was planning to replace with a Lithium battery anyhow, but just doing sooner rather than later. I ordered a new battery, so Tesla is in the garage for a few days until the battery arrives. I will be taking the defunct battery to Tesla SC for them to review as I already had an appointment scheduled 2 weeks out.

I am fortunate the factory AGM battery did not breach or leak inside the car. After about 3 hours, battery is still too hot to touch on one end and not 100% sure it is safe, so it is outside and away from my house and car. This my first issue with this Tesla ever in 45K miles and almost 2 years.

Just wanted to share this story in case anyone else gets that strong sulfur smell, probably means the battery is dying and needs to be replaced. I had noticed it a few days before in the AC since the air intake is right next to the battery, but didn't think much of it at the time.

 

[smatthew]

Tesla will replace the tow hook cover for free. When I had mine replaced the mobile service tech just wanted to see how I tried to open it. Once he saw I was using the right technique, it was free.

I think the bumper plastic is molded too tight on some earlier cars. Despite having the tow hook cover replaced, I'm fairly certain if I try to get the new one out it will also crack since the bumper holds on to it too tight. Using some sort of plastic pry bar can help remove it without damage.

Shame that the battery failed like that, but that's definitely not Tesla's fault. Occasionally batteries are just defective. I am surprised that the battery is bulging that badly. I would have expected the battery to use the vent tube. '

Remember that the 12V battery is both a) different from what is used in ICE cars and b) used differently that in ICE cars. ICE cars need "Cold Cranking Amps" to turn over the engine. And then all power comes from the alternator. Teslas use a deep cycle battery. When the car is awake all the power comes from the Power Conversion System. But when the car is asleep the battery slowly drains from the stuff that's still on in the car (like the cellular modem, waiting for the call to wake up the car, vcfront which is monitoring battery voltage, vcsec which is looking for bluetooth keys/keycards). Now, the car will recharge the battery as soon as it gets low, but there are still cycles being put on the battery.
Early in the Model 3's life cycle the car had a much higher "drain" when sitting idle. You probably remember losing more than a few miles overnight in the beginning. They've tightened things up so the car uses much less power while sleeping now, but those of us with earlier cars have had our 12V batteries put through many more charge cycles than newer cars, leading to earlier failure.
Good news is all the changes Tesla made were in software. So even if you stuck in a new standard deep-cycle battery your next one should last significantly longer.

 

[skraack]

Thanks for that additional information. I will ask Service Center about the Tow hook cover when I take it in 2 weeks. Having the Autopilot 3.0 computer installed to activate Full Self Driving capabilities.

I did know about the changes made to battery management, but didn't realize how important that 12V battery was to the whole ecosystem until it went out. I guess some people have gotten a 12V battery low notice in the car. We got none of that. I also track phantom drain with several API apps, and it has gotten a lot better in recent months as compared to new.

Agreed, certainly not Tesla's fault. But I think Tesla will want to know what happened to a critical system battery in their car. As an engineer, I want to be aware of all systems faults and failures. This failure will be totally off-grid, as the car hasn't been able to phone home since the battery dead shorted. And I expect, once I install a new battery, it will come up as if nothing happened. I hope it is smarter than that, but without power, not sure how it can know. The logic and computer can't collect data if it is not running.

Lithium Battery will be here Thursday. I'll post back the results when we get the Tesla running again.

 

[Skione65]

Are you replacing it with an Ohmmu? Let us know what you think.

Ski

 

[Rachmaninov]

I have a lot of experience using 12v Lithium batteries (Specifically Ballistic brand) in race cars and motorcycles but no experience or knowledge with Tesla 12v battery use. Ballistic is now out of business but I still use several of their batteries in motorcycles and race cars.

The 12v lithium batteries I’ve used had some great functionality but also had some key drawbacks.
Pro -
Extreme light weight and small size for their cranking power
Retained power over long down time = example motorcycles or race cars not used for months did not require trickle charger

Con -
Requires special chargers to properly balance cells
Suffer permanent damage if overcharged slightly or allowed to fall below 5-10% of normal charge
Do not do well when exposed to small parasitic draw

I am relatively sure that newer / different brands may have addressed some of these issues but I would caution using any 12V lithium battery in a Tesla if parasitic draw exists.






l

 

[smatthew]

I think the reason you didn't get a failure message is because the 12V battery failed so extremely and suddenly.

I wonder, when I buy a battery at the store the manufacturer warranties it for XX months. Do we get anything like that on our battery? The manufacturer might even be interested in getting that battery back to do failure analysis.

Once the car is back online, it might be worthwhile to call the Tesla Service number (the one from the T menu in the car) They usually seem to enjoy looking at log files. I bet the car logged something.

 

[mrau]

At 45k miles the battery should still be covered by warranty from Tesla. Just in case you wanted a spare battery if the lithium did not work out.

 

[TheDom]

We're also in Florida with an Aug 2018 manufacture date Model 3, and had our 12V battery fail at about 14 months in. It was also bulged out pretty bad on the one side, and Tesla mobile service replaced it under warranty.

 

[skraack]

Are you replacing it with an Ohmmu? Let us know what you think.

Ski

Yes, I ordered Ohmmu Lithium battery. Should be here Friday. I will post results once we get online.

And good call on the warranty battery through Tesla. That will be a great backup if we have issues again. My wife would have freaked out if that had happened to her while she was out somewhere.

 

[skraack]

We're also in Florida with an Aug 2018 manufacture date Model 3, and had our 12V battery fail at about 14 months in. It was also bulged out pretty bad on the one side, and Tesla mobile service replaced it under warranty.

Thanks for sharing!! Good to know I am not the only one.

 

[skraack]

Con -
Requires special chargers to properly balance cells
Suffer permanent damage if overcharged slightly or allowed to fall below 5-10% of normal charge
Do not do well when exposed to small parasitic draw
I am relatively sure that newer / different brands may have addressed some of these issues but I would caution using any 12V lithium battery in a Tesla if parasitic draw exists.

I do know what you mean. I have tons of experience with Lithium as well using them heavily for R/C Race Cars and R/C Airplanes. Those RC batteries were raw cells and needed a special charger to balance and monitor the cycle.

I would not consider a Lithium battery without an Internal Battery Management System. The BMS will balance the cells and make sure you don't overcharge or overdraw the battery. Companies like Ohmmu and EarthX seem to be doing a great job with this now. EarthX just got FAA certified for General Aviation Aircraft usage. That is a huge indication to me that the technology and marketplace is catching up with the demand. The weight savings alone is worth the cost to me.

 

[lUtriaNt]

lots of cats (myself included) have switched over to the ohmmu battery and have not had any issues. i swapped mine out even with no problems with the stock battery. worthwhile investment for me with more benefits over the conventional design.

 

[DeanP]

My battery is on its way out. I'm the second owner and am wondering if this would be covered under warranty. TIA!

 

[Uncle Paul]

Tesla has been very liberal with covering these 12V batteries under warranty. Even do it via Mobile Ranger Service.

 

[DeanP]

I hope so. I put in a service call thru the app. Stated they'll be out 7/30. I asked about the coverage but no info yet. Thx!

 

[DeanP]

Tesla has been very liberal with covering these 12V batteries under warranty. Even do it via Mobile Ranger Service.

You're right. There is no charge. Thank you Tesla!

 

[skraack]

I installed my Ohmmu Battery yesterday and after one day of driving, no issues. New battery went in really easy. I followed all of the instructions on their website and I had no issues. Very Easy!! Biggest advantage I noticed is the subwoofer came to life with this new battery. I can actually feel some thump now. When the battery was finally connected, the M3 immediately did an upgrade that was pending. New software, new battery, love this car more than I should....

I will try and exchange my busted battery via warranty on my next SC visit in 2 weeks when I have FSD computer upgraded. Would be nice to have that at my house as a backup.

Thanks to all for the advice and comments!!!

 

[Skione65]

I installed my Ohmmu Battery yesterday and after one day of driving, no issues. New battery went in really easy. I followed all of the instructions on their website and I had no issues. Very Easy!! Biggest advantage I noticed is the subwoofer came to life with this new battery. I can actually feel some thump now. When the battery was finally connected, the M3 immediately did an upgrade that was pending. New software, new battery, love this car more than I should....

I will try and exchange my busted battery via warranty on my next SC visit in 2 weeks when I have FSD computer upgraded. Would be nice to have that at my house as a backup.

Thanks to all for the advice and comments!!!

Sounds great! I’ll be doing the same if/when my 12V bites the dust. On another note can you weigh the Tesla 12V AGM battery? Curious what the weight difference is between that and the 11 lb. Ohmmu.

Ski

 

[lUtriaNt]

Biggest advantage I noticed is the subwoofer came to life with this new battery. I can actually feel some thump now.

LOTS of us who have this battery in the car have experienced the SAME result! some cats on here have tried to dispute this and say its placebo, but virtually everyone who has this battery say otherwise.

i play wave files in my car from recorded vinyl and my favorite tracks to test the bass is "Feel the bass" from DJ Magic Mike. the rear view mirror vibrates and the seats feel like you got a massager motor in them..

appreciate you posting your results.

 

[Stratman]

I do know what you mean. I have tons of experience with Lithium as well using them heavily for R/C Race Cars and R/C Airplanes. Those RC batteries were raw cells and needed a special charger to balance and monitor the cycle.

I would not consider a Lithium battery without an Internal Battery Management System. The BMS will balance the cells and make sure you don't overcharge or overdraw the battery. Companies like Ohmmu and EarthX seem to be doing a great job with this now. EarthX just got FAA certified for General Aviation Aircraft usage. That is a huge indication to me that the technology and marketplace is catching up with the demand. The weight savings alone is worth the cost to me.

A Lot of the 12V automotive Lithium replacement batteries have BMS/ regulation built inside the battery case. All that is presented outside the case is the two terminals. Assume the Ohmmu is like that if it requires no special charging regime and a true lithium drop in replacement battery. It would be interesting to see inside one.