Model 3 12v Battery issues, monitoring, Aftermarket replacement

[stopcrazypp]

Tesla says a software update was supposed to provide advanced warning of the 12V about to go bad. My first one went bad about 3 years from the date of ownership. About 40k miles. I figured maybe there was a bug in the software and it didn't notify me. I was stranded and had to get towed and Uber everywhere for a day.

Well fast forward a bit and my other Model 3 also had the 12V unexpectedly go bad and not warn me. Also almost exactly 3 years to the date and 39k miles. Once again I had to wait for a tow and go through this whole process.

Is anyone else not getting 12V warnings and having the battery go bad?

That warning works for some people and doesn't for others. The reality is not all failures are predictable. It could happen in a "straw that broke the camel's back" way, in that one cell weakens and then it quickly brings everything down. Then the battery would look fine the whole time up until it failed.

 

[miimura]

@miimura -- a NOCO would've been a great investment both to charge and detect a bad battery. It sounds like even the base model ($30) would help with a trickle charge and bad battery detection, but is there a specific model that you would consider a best buy?

I recently bought this NOCO Genius 5 (5A). It is more powerful and smaller than my older G3500 (3.5A). It has 6V and 12V support as well as specific support for traditional flooded, AGM, and 12V Lithium. You should use the AGM mode with a Tesla S/X/3/Y.

https://smile.amazon.com/gp/product/B07W8KJH44/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[sodakar]

There's always tomorrow. I think I would just drive your own car. My understanding (and again, it is not based on personal experience, so YMMV! - obviously there is perhaps some increased risk of disablement) is that the car will work just fine without any 12V battery. It will just complain about it.

There's really no reason for the 12V after it bootstraps the contactor closure & DC-DC converter power up, as I understand it, because then the DC-DC is providing the 12V for all the components that need it...

Tomorrow came, I re-connected the negative terminal, and just drove it into the service center. While my car was in a limbo state of "being towed," they were kind enough to sort me out while I waited, so I was able to say farewell to the old:
AtlasBX 85B24LS P/N 1129182-00-B, 2018/07/11
...and hello to the new:
Hankook 85B24LS P/N 1129182-00-B, 2021/08/03

Communication was a bit of a challenge, and Tesla has some room for improvement.

When I called the service center's phone number, it kept sending me to my closest service center where my car wasn't scheduled to go
When I e-mailed the service center's e-mail address, no one replied
When I messaged via the Tesla app, no one replied

My questions about logistics and scheduling were not complex, and I just needed 5 minutes with someone, but was unable to get answers using the above methods, so my only option was to drive and show up there, which is pretty ironic, given my car was disabled (in theory).

Kudos to the forum members for their encouragement and support, and walking me through the steps to better understand the role of the 12V battery, especially when it's dead/half-dead/zombied.

 

[sodakar]

Not to thread detail, but as a follow-up to the battery swap, remote climate control via the app no longer works. Rebooted, reinstalled, re-paired everything imaginable (card, app, phone, car, wifi, BT, etc), but no go.

I didn’t find any instance of “battery swap” and “remote climate control not working” in the forums, so including it here for reference. Climate control works when I’m in the car. It’s possible that it’s just bad luck, but after zero issues with remote climate controls for 3 years, the timing lines up too much.

According to most threads about failed remote climate control, it seems like it’s resolved by the service center and/or random firmware update, so I will try to remember to post an update when it’s resolved.

Firmware 2021.32.22
iOS 15.0.2 (edit: typo, no I don’t have a future release)
App 4.2.0

Edit/Update:
problem discovered at 12pm
resolved itself at 6pm
Root cause / fix: unknown
(Shrugs)

 

[Rocky_H]

and wala everything came back to life

This drives me up the wall, more than anything else. It's "voila".

definition: voila - Google Search

 

[Jack Red&White]

I've had my car for just over three weeks and there's already a 12v failure. It was plugged in and fully charged when it notified us with the litany of error messages. Thankfully we could open the trunk to attach a 12v backup and get it in tow mode to get it to the SC.

 

[RandyS]

Just adding a data point of my experience with an Ohmmu replacement in my Model 3. I followed the steps on their web video and disconnected the connector under the rear seat, etc. The replacement process went well. I was particularly interested in any discernable audio system differences after the upgrade. So here's what we did to test that out....

* My car had the Ohmmu replacement battery installed
* My girlfriend's Model 3 (with the same premium audio system) was parked near mine (she had an OEM Tesla 12v battery that was 6 months old - replaced once)
* I copied some favorite songs that we both knew well to two separate thumb drives; tried to choose a song or two with some dynamic range and some good bass
* We installed a thumb drive into each car
* I verified that the "tone controls / eq settings" were the same in both cars
* We listened to one song in my car and then moved to her car to listen to the same song
* After that, we got back in my car and played the same song again
* On a couple of songs, we even played it a second time in her car after the second time in my car
* After finishing with one song, only then did we move to another song (so as not to confuse ourselves)
* We played the songs at a volume level that was about 75-85% turned up in both cars

Both of us heard positive differences in the stereo in my car with the Ohmmu battery vs. her battery over the course of several songs. We both felt that my car sounded better.

I will admit that it was not a night and day difference. But I've regarded myself as an audiophile for several years, and I could tell the difference between the two playbacks...The Ohmmu car seemed to be "punchier", more dynamic, cymbals sounded clearer, with a slightly better bass response, etc.

Like I said, not a whole lot of difference. But it was definitely discernable...

Anyways, it was a fun exercise. Wasn't expecting to be able to hear a difference, but I did...

 

[Rocky_H]

I will admit that it was not a night and day difference. But I've regarded myself as an audiophile for several years, and I could tell the difference between the two playbacks...The Ohmmu car seemed to be "punchier", more dynamic, cymbals sounded clearer, with a slightly better bass response, etc.

Ha haa.
"Now I'm getting in the car that doesn't have the fancy expensive battery. Let's see if I can tell that it sounds worse."

This is rather ridiculous if you know which one you're getting into, and it's not a blind test. The human mind is very suggestible.

 

[RandyS]

Ha haa.
"Now I'm getting in the car that doesn't have the fancy expensive battery. Let's see if I can tell that it sounds worse."

This is rather ridiculous if you know which one you're getting into, and it's not a blind test. The human mind is very suggestible.

I don't know how we could have done the test any better, except maybe to have masks on, act like a blind person, and have a friend of mine escort us from car to car parked on flat ground. And that, I will tell you, is MY definition of ridiculous...

 

[Rocky_H]

I don't know how we could have done the test any better,

...and yet you describe it immediately after:

except maybe to have masks on, act like a blind person, and have a friend of mine escort us from car to car parked on flat ground.

I don't know why the ground would have to be flat, but yes, have someone lead you to the cars blindfolded, so you don't have that bias of knowing which one it is.

And that, I will tell you, is MY definition of ridiculous...

Thinking that the 12V battery changes the quality of your stereo system..... Anyway, if you want meaningful results, you would need to do something like that. This thing in particular has a strong bias to it, where people are highly motivated to be proven that they were right in making a big purchase and perceive a lot of benefit from it instead of feeling like it was a waste of money.

 

[miimura]

It would be easy enough to do the blind test with a neutral party that didn't know which car had the upgraded battery. Having the person who installed the battery doing the test himself is inherently the problem.

 

[M109Rider]

If the two batteries deliver the same power (and I don’t know if they do), it shouldn’t change the sound.
Even if they deliver different power, wouldn’t the computers and software ensure power is the same regardless ?

I’m not sure of any of this, but seems logical at first glance, that the battery would make no difference. ?

 

[miimura]

If the two batteries deliver the same power (and I don’t know if they do), it shouldn’t change the sound.
Even if they deliver different power, wouldn’t the computers and software ensure power is the same regardless ?

I’m not sure of any of this, but seems logical at first glance, that the battery would make no difference. ?

The theory is that the Lithium battery has less voltage sag under load than a lead-acid battery, so it can deliver more stable transient power to the audio system. However, I am unconvinced that the Model 3 electrical architecture can actually deliver this benefit. I think the bulk of the current supplied to the car is coming from the PCS DC-DC converter and little if any current is actually being supported by the battery itself. One would have to put a current shunt on the battery line and look at the differential voltage across the shunt with an oscilloscope to see if there is actually transient current supplied by the battery.

 

[Rocky_H]

The theory is that the Lithium battery has less voltage sag under load than a lead-acid battery, so it can deliver more stable transient power to the audio system.

But speakers are driven by amplifiers, so there is an extra layer of buffer there. The capacitors in audio amplifiers supply that "bursty" type of output while being supplied with a more steady input so they don't sag that supply.
(Huh, I realized I couldn't use the colloquial term "amp" for an audio amplifier, because I didn't want that mixed up with amperes.)

 

[ahmadr]

The theory is that the Lithium battery has less voltage sag under load than a lead-acid battery, so it can deliver more stable transient power to the audio system.

In general, (at the same capacity,) lead acid batteries have a lower internal resistance than lithium ion batteries.

 

[Frank99]

It's far, far more likely that one car sounds different than the other, than it is that the battery makes a difference. Crap in the trunk or in the car will change the sound, a body panel that's more or less stiff in one car than the other will change the sound, a non-functional speaker in one car will change the sound (there are, what, 15 of them after all).
Try swapping the Ohmmu into your girlfriends car and running the same test. If you want to A/B test, have a friend swap the batteries around several times without telling you which one is where, and see if you can tell.

 

[Darmie]

I think this is a much cheaper option over the Ohmmu if you are sold on sound alone.

 

[artsci]

I’ve had the 12v battery problem ever since I purchased the Model 3. I’ve found a solution that means you’ll never have the problem again, although you will have the “replace 12v battery” warnings, but you can make them disappear. The solution involves these steps.

1. When you get the 12v battery warning, disconnect the 12v battery (make sure the right rear door and frunk are open when you disconnect the 12v). I bought this device to make remote disconnection of the 12v easy: https://www.amazon.com/gp/product/B08KZJLX61/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

2. Do a hard reset of high voltage system: Tesla Model 3 Hard Reset - Mountain Pass Performance
When you do this the 12v warning should disappear especially if you have have replaced the 12v battery with a LiFeP04.

3. Replace the 12v battery with a Lithium Iron Phosphate (LiFeP04) battery (I acquired an EarthX ETX900 but there are many other choices available). Amazon.com: EarthX ETX900 lithium iron phosphate (LiFePo4) battery for experimental aircraft with 80 amp alternator or less!

4. Buy a LiFeP04 battery saving charger and mainainter and use it once a week to charge and maintain the LiFeP04 battery. IMHO the Optimate TM-291 is the best choice. https://www.amazon.com/gp/product/B00AHG7O74/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

If you take these steps you’ll never have the 12v battery problem again. It’s a bit expensive but the ROI over several years will be financial and in peace of mind.

 

[Kevy Baby]

I’ve had the 12v battery problem ever since I purchased the Model 3. I’ve found a solution that means you’ll never have the problem again, although you will have the “replace 12v battery” warnings, but you can make them disappear. The solution involves these steps.

[snip]

4. Buy a LiFeP04 battery saving charger and mainainter and use it once a week to charge and maintain the LiFeP04 battery.

This sounds like a LOT of work to "never have a problem again" - sounds like you've got a problem every week! I've had my 3 for about 134 weeks (almost 50K miles) and have never once had a battery issue. I am sure I will, but the inconvenience of replacing will be a LOT less hassle than once per week maintenance (which involves removing the back seat).

I'll pass

 

[dfwatt]

This sounds like a LOT of work to "never have a problem again" - sounds like you've got a problem every week! I've had my 3 for about 134 weeks (almost 50K miles) and have never once had a battery issue. I am sure I will, but the inconvenience of replacing will be a LOT less hassle than once per week maintenance (which involves removing the back seat).

I'll pass

I think that list that you commented on is confusing because the poster does not specify that the reset is only done when you get a battery failure warning. The trickle-charging on the other hand is what you do once a week. Nobody's resetting their system once a week that I'm aware of and it certainly wouldn't be necessary or recommended.

That's said it is unclear to what extent trickle-charging lithium ferric phosphate batteries protects them. It is a great idea on the other hand if you get this warning and you have an aftermarket battery to trickle charge it until you can resolve the problem because the normal charging circuit from the DC DC contactor system will not work once the cars operating system detects any kind of fault in the 12-volt subsystem triggering the error code. In other words the battery will slowly run down and then your vehicle will not start or run. Trickle-charging got us through two weeks until our OEM lead acid battery could be replaced by Tesla. But when that fails on my wife's car in a few years at which time the car will clearly be out of warranty we will definitely go with the aftermarket lithium ferric phosphate battery from Ohmmu. Their support has been most impressive and as soon as it became clear that the change in the 12 volt charging protocol was tripping the bms in our aftermarket battery (too high voltage Drive) they got us a solution at no charge.