The whole irony here is that it's the improved monitoring logic that caught the Ohmmu (since it's very much a broken Lead Acid battery). It didn't "no longer recognize" the battery- it saw a connected battery that wasn't acting like a lead acid should, so it flagged it as bad.
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"Proactive" 12v battery replacement - good idea or overkill?
- Thread starter joebruin77
- Start date
The Ohmmu was never designed properly in the first place. If it's designed to be a drop-in replacement for a lead acid battery, then it should be actively managed and made to look like a lead acid battery in terms of I-V characteristics. When the charging system detects that the battery is dying, it should mimic a dying lead acid battery.
stopcrazypp
Well-Known Member
Most drop in replacement of batteries don't need to simulate the original in that amount of detail, it only needs to tolerate the charging profile of a standard lead acid (which a LFP battery certainly does) and handle the discharge demand of it. A LFP wired appropriately with a standard BMS would handle that in most cases (starter batteries for most cars).
The requirements that Tesla imposes is unusual in that it is trying to detect battery failure so that it examines it in a lot more detail. Trying to simulate a lead acid in that detail would require much more advanced circuitry, probably a DC-DC converter and maybe something to adjust the resistance.
Have you ever read what you wrote before you hit "post reply" it will absolutely leave you on the side of the road if it dies. Dead 12v you need a jump or to be towed that's not hyperbolic that is a fact no matter how much you think your right there you are wrong.
This is true, even a new battery could die. However I'd trust a new battery manufactured recently than the one that's been baking in the Florida sun for the past three years in my car. From experience, I've had enough dead 12v's die to know just to swap it out otherwise be prepared to jump it or call for a tow truck. Different climate conditions might yield better or worse results.
Again, you're being hyperbolic. You mean it will strand you in a parking lot, or your driveway.
It is not possible for the 12V to die while you are driving and require you to coast over to "the side of the road" and be stuck in the middle of nowhere, like a 12V battery in an ICE car can, and like your language suggests. You can pull the 12V out of a Tesla and as long as it is awake, it will keep going no problem.
If you're sure that I'm wrong, find me a single example of a 12V battery dying while someone was in the car, causing the car to stop, not just coming out to a car after 30+ minutes of nobody being inside to a car that won't open.
Let me be very clear since you've jumped to the wrong conclusion. I did not say nor mean a 12v could die while driving, that my friend was your interpretation, your assumption. On the side of the road, believe it or not is where some of us park sometimes. That reference means for example your parked on the side of the road come out of your house or work or whatever and 12v is dead. This has happened to me a couple of times in the past with previous vehicles.
My advise was to those of us in hot climates which last time I checked wasn't Seattle. I know how frustrating a dead 12v is I hope it doesn't happen to others. To be absolutely crystal clear so you don't interpret anything else the wrong way none of that advise even applies to you. Also I wouldn't recommend removing your Tesla's 12v while the high voltage pack is connected, this is assuming you even own a Tesla.
Of course it’s not recommended, but his point is very valid. In earlier firmware, that 12V was needed to support the car in all cases. Now, with the improved firmware*, should there be a 12V fault (including a disconnected 12V battery), the car will throw an alert and prevent the HV contactors from opening, thus ensuring the car remains awake and drivable. Very different behavior than what we saw in the “early days” of expiring 12V batteries. Unless and until the 12v battery goes dead *while* the car is asleep, it’ll be fine. Thus the likelihood of being stranded somewhere besides home is greatly reduced.
* Improved for those of us with stock batteries - an abject nightmare for the Ohmmu crowd.
His point is irrelevant, he's a troll. Trying to stir the pot.
Interesting so in my case and I'd assume many others when our cars go to sleep while at work for example. We're still stranded. That is my point that is exactly why I said what I said.
I didn't come in here to argue about a passing comment just throw in my 2c and move along.
So because you have a problem with the other guy you throw me a thumbs-down? Not sure I earned that but whatever.
And my point is that if the car senses any issue with the battery it *won’t* sleep. That’s a *major* prophylactic against the car just being dead. The nature of lead acid batteries - typically - shows signs of wearout before total failure. This is to our advantage, and Tesla’s firmware now takes advantage of it.
Possible for sudden death of the 12V in a way that requires a jumpstart? Sure. But that’s no different than any other car on the planet. I’m sure not going to play the what-if game every day …. I’d never get anything done.
Keeping SENTRY on also keeps the car awake and prevents getting stranded.
I didn't come here to get into an argument with a couple of men children who want to be right or twist the narrative in order to feel correct. Yes you got a thumbs down so did I from the troll yet did I get offended by it. Get over it nice on Karen.
Down thumbs are rare on this site, so whenever it happens, it definitely gets noticed, and people want to know why. Further, it's pretty rare for people here to get into name-calling, etc. Common elsewhere, but definitely rare here.
Adding a bit more info...despite other users here claiming to know what I should or shouldn't have done and having the prescience to know what will happen when I went back to Tesla to get this issue resolved...
Tesla mobile service was great for this request. Arrived on time, very efficient and friendly - plopped in the new Tesla-approved 12v...and charged me absolutely nothing - $0.00.
The Ohmmu guys may be a good group. But they will always be playing catchup to Tesla software - fair or not. I'm not interested in having their compatibility issues with Tesla to end up being my problem.
Thank you! Just to double verify, I am now feeling less worried about the 3rd birthday of my 12 volt battery. Up till now, I have vowed to myself to replace the battery at around 3 years no matter what. Now I am going to wait for a warning message first, unless I am about to go on a long trip or something.
RayK
Active Member
I went until one month shy of having the car for four years before changing the 12V battery. No warning message; just a pro-active replacement prior to a trip up to Oregon. Had about 23.5K miles on the car at that time. This was June 2022.
I'm approaching 50k miles and 4 years on my 12V, and it's holding strong. Maybe it'll be a 4th birthday gift for the car... or, I'll keep rolling the dice to play the "what can I get out of it?" game. I'm inclined to keep rolling the dice; hasn't given me any reason not to.
I got my warning message at 45 months, so it was changed under warranty, but I was planning to do it proactively, soon.
Given how many batteries from that era go at 3.5-4.0 years, I think a proactive change is a good idea.
However, later firmware and electronics and batteries may last longer. If I bought a Model 3 or Model Y last year, I wouldn't plan on changing it at 3.5 years... I'd wait to see how others are faring and if things have changed.
Given how many batteries from that era go at 3.5-4.0 years, I think a proactive change is a good idea.
However, later firmware and electronics and batteries may last longer. If I bought a Model 3 or Model Y last year, I wouldn't plan on changing it at 3.5 years... I'd wait to see how others are faring and if things have changed.
Hello all 
new member/first post:
I thought I’d jump in here as my 2019 3 (LR) just popped the warning about the 12v at the 67,000 mark. Battery itself is swollen on each side, similar to the batteries talked about here. I bought a Costco 51R as I wait for a scheduled Tesla appointment (hectic as it’s Christmas).
I also uninstalled the Oem battery and put it on my tender for an hour, that has made the warning go away (for now).
I read the first 8 pages of this thread, and it seems like this is as much as one can do.
Car has been excellent going into year 3-4.
Cheers
new member/first post: I thought I’d jump in here as my 2019 3 (LR) just popped the warning about the 12v at the 67,000 mark. Battery itself is swollen on each side, similar to the batteries talked about here. I bought a Costco 51R as I wait for a scheduled Tesla appointment (hectic as it’s Christmas).
I also uninstalled the Oem battery and put it on my tender for an hour, that has made the warning go away (for now).
I read the first 8 pages of this thread, and it seems like this is as much as one can do.
Car has been excellent going into year 3-4.
Cheers
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