12v battery issue, Tesla unsatisfactory response

[CertLive]

Do you have some actual numbers on “the amount of 12V battery replacement complaints” other than just perusing this forum? If so please share, because I haven’t seen any actual data on the topic. We know roughly 500k Model 3s have been sold (at least that’s the number I’m pulling out of memory from an InsideEVs article I read a month or two ago, and I’m 48 so the memory isn’t what it used to be) so if you have hard data on early 12V failures we can calculate the early failure rate. Then all we need is early 12V failure rate for the average car and we can compare the two in order to determine if this is really an issue worthy of over 300 posts to this thread or if this is typical.

Well it seems there is some sort of issue here and it also seems that 2 years for a 12v battery to die is quite bizarre. So in that light compared to other cars on the road its an early failure. Unless its a very cheaply made battery with a bad reputation? Not all is created equal but 2 years is not good enough. 300 posts is quite a large and well thought out issue. Look at brilliant investigation going on by engineers. Good luck getting the real 12v failure rate figures but if its 1 or 90,000 cars it is not good enough. Not if you compare it to ice EV will replace. Even saw a video yesterday of the new VW ID 3 lose its battery power after 5000 miles.

 

[CertLive]

We can quibble about whether it is a difficult job, but I insist that we not quibble about what I said was a target.



I agree that with selection bias it is impossible to actually say whether Tesla 12V are failing earlier. It’s just anecdata.

So instead, we have to use science, to put forward a reasonable hypothesis for why Tesla Model 3 might be wearing out the 12V faster. Above.

Some anecdata:

Subaru #1: Battery lasted 5 years, and then I sold the car.
Subaru #2: First battery failed after about 5 years. Note the STi has a very hot engine compartment so would have been a stressful use case. Subsequent non-OEM batteries lasted about 4 years each.
Highlander: 4 years so far. Still going. Unfortunately I have inadvertently killed the battery twice in the last 6 months, and the resulting sulfation will likely kill it sooner now. Guess I need a desulfating charger...though they probably don’t work.

Spark EV: 4 years and counting.

Tesla Model 3: 2 years and counting. Not clear at the moment whether there is anything wrong with my 12V.

Big plus: Tesla battery is cheaper and smaller than any battery I have had in my prior cars. It’s a non-AGM, small, relatively cheap battery. $85.

So its fair to say 2 years would be a bit premature but so far so good with the 3.

 

[neurocutie]

Not sure, but a hell of a lot less than my laptop, which is a much closer approximation given that the MCU is x86-based. (honestly, a move that I strongly disagree with - the Atom CPU they chose is a piece of $#!+ that would be out-performed by a good CPU from 2007 or a flagship phone of 2016).

good to know, that says it right there... when the whole world is moving or already using ARM...do they develop on Macs perhaps? (going to ARM as well...) Hope Nvidia doesn't botch things up...

 

[EnrgyNDpndnce]

Well it seems there is some sort of issue here and it also seems that 2 years for a 12v battery to die is quite bizarre. So in that light compared to other cars on the road its an early failure. Unless its a very cheaply made battery with a bad reputation? Not all is created equal but 2 years is not good enough. 300 posts is quite a large and well thought out issue. Look at brilliant investigation going on by engineers. Good luck getting the real 12v failure rate figures but if its 1 or 90,000 cars it is not good enough. Not if you compare it to ice EV will replace. Even saw a video yesterday of the new VW ID 3 lose its battery power after 5000 miles.

There’s no doubt early failures are bad and of course Tesla should replace those that fail within the 4/50k warranty period. The question is, what is the early failure rate and how does that compare to industry standards. To read some of these comments you would think no other car has ever had a 12V fail in less than 2 years which of course is absurd. So if Tesla has 1 in every 50k cars experience an early 12V failure and the industry norm is one in every 500k cars, well then Houston we have a problem. If however the early failure rate in Teslas is relatively close to that of the industry, then nothing to see and move along. My point all along is that we don’t have any of that data and all of these posts suggesting this may be a major issue are premature. Once we have some data we can have a more informed discussion.

 

[FalconFour]

Some anecdata:

I'll add my anecdata as well:

3 LEAFs from 2012-2018 - one replacement battery but I milked the hell out of my 2013 Leaf up 'til it was totaled - it definitely should've been replaced as I kept a 12v jump-battery with me and used it about once a month when it died. My analysis of how it was using the 12v battery was simply that it likely had a FW bug that unpredictably left some system running after shutdown (maybe 1 in ~100 shutdowns), causing it to be killed unexpectedly - and it didn't fully charge it, leaving it in the mid SOC range its whole life, presumably for the SL trim's solar panel to recharge it (mine was an S - it didn't have that solar panel). Solidly in the realm of "design flaw" as 2014+ seems to have fixed that.

Model 3 LR/RWD from mid-2018 to today: its 12v battery performs as good as new (by bench test) up 'til Aug 2020, but I replaced it with a lithium battery just on opportunity.

The Tesla-based RAV4 EV also seems to have 12v issues, which just goes to play into that EVs just seem to have weird 12v battery management issues in general. Hard to understand why that's the case given the giant main battery they carry around.

As to sustainability, I honestly think the only reason EVs even use lead 12v batteries is that they're the only remaining useful application for large amounts of lead... and they're usually highly recyclable (much like aluminum cans). So it's kind of a closed loop system, and if a major automaker started to forego lead batteries, I dunno... maybe there'd be a surplus of lead nobody is using?

 

[FalconFour]

OK, here's the first couple days of data with the 12v battery logger. It has a hell of a problem with saving/storing the chart data, though, so it's been tough, but it seems like charts come out clean in the end. (just can't view the historic charts 'til the next day for some reason). It also never seems to think the battery is doing anything but charging - even when the car is asleep and it's definitely not charging, it's discharging. It's basing its idea of "charging" on voltage level, which isn't quite right for a lithium battery...

So here you go, my lithium battery behavior.

This was also doing an update, too... starting at 16, and likely just before the 17 mark was where it rebooted and used the battery briefly, then it went back to sleep at 18. Before that, I'd been driving it a few times throughout the afternoon.

Today, so far. Note that combined with the previous chart, that's at least 12 hours of uninterrupted sleep.

Note the spike in today's chart. The spike doesn't represent the time it was awake - I was sitting in the car for a good couple hours (from about 11:45 to 14:00) driving and later watching YouTube at home in the car. So, that long lead-off after the spike is actually while the car is awake, choosing to bring the voltage down there. Also note it rests higher than the sleep voltage. So, that seems to be its choice to keep it at that specific voltage... also, what's up with the steps in the Y axis? 9.0v (+2) 11.0v (+1) 12.0v (+1) 13.0v (+2) 15.0v... makes it kinda hard to read, but oh well. Point is, the car was awake there

It completely lines up with my observations as well - the car sleeps peacefully for hours and hours until I wake it, and generally for no other reason.

 

[lUtriaNt]

photos dont show mate...

 

[FalconFour]

photos dont show mate...

oh you have to be sh^ttin me. I use "Copy Image" and Ctrl+V out of Google Photos and the thing pastes it as a URL? (so obviously only I can see the images, which look fine here!) First emojis don't work, now this I really wish this forum would use Discourse instead -_-

Let me try proxying it through mspaint instead, then. I can't edit after a certain time (THANKS, CRAPPY FORUM SOFTWARE) so I just have to repost.

Once more, my lithium battery behavior:

(which currently looks like a "broken image" icon but with an attachment now on the post)
This was also doing an update, too... starting at 16, and likely just before the 17 mark was where it rebooted and used the battery briefly, then it went back to sleep at 18. Before that, I'd been driving it a few times throughout the afternoon.

(which also looks like a "broken image" icon right now as I write this)
Today, so far. Note that combined with the previous chart, that's at least 12 hours of uninterrupted sleep.

Note the spike in today's chart. The spike doesn't represent the time it was awake - I was sitting in the car for a good couple hours (from about 11:45 to 14:00) driving and later watching YouTube at home in the car. So, that long lead-off after the spike is actually while the car is awake, choosing to bring the voltage down there. Also note it rests higher than the sleep voltage. So, that seems to be its choice to keep it at that specific voltage... also, what's up with the steps in the Y axis? 9.0v (+2) 11.0v (+1) 12.0v (+1) 13.0v (+2) 15.0v... makes it kinda hard to read, but oh well. Point is, the car was awake there

It completely lines up with my observations as well - the car sleeps peacefully for hours and hours until I wake it, and generally for no other reason.

 

[Tjhappel]

Hate to repeat myself, but after jumping back into this thread it seems worth it. There is no reason a dead 12V should strand a Tesla owner either. It’s really no different than an ICE. When mine died (after 80k miles) I jumped in my wife’s Volvo and headed to O’Reilly. After educating the kid who worked there (had never heard of Tesla) I bought the battery needed and returned home. Installed new battery and BAZINGA, not stranded. Entire process took maybe 90 minutes soup to nuts. This is really a non-issue unless you are unwilling or unable to perform a simple maintenance item on the vehicle. Some people are and that’s fine, to each his own. But those people probably wouldn’t change the 12V on an ICE either so again, no difference.

Just say that out loud again in a mirror.... you had to educate a worker at a professional shop!! Wtf do you expect a “normal”person to do?? Read 17 pages of this *sugar* and then go educate a kid???

 

[Tjhappel]

The difference is, with the Tesla, your ARE stranded, i.e. the Tesla won't run until you REPLACE the 12V battery. With ICE, after the jump, the car WILL run, potentially for days or more, but at least enough to get you to where you need to go at that moment. Also, my ICE batteries have lasted 5-8yrs. It doesn't seem the Tesla 12V batteries last half of that...

not saying this is a fatal flaw, but I do think Tesla can do better...

Agree totally... instead of educating “kids” at oreilly autoparts who “haven’t heard of a Tesla” maybe tsla could tell them what battery they use??? Seems easy enough

 

[Tjhappel]

El touché. Pagination is a b*tch here. Really chaps my ass that everything I wrote on page 14 will be lost to the sands of pages with no way to really call attention back to it (other than me, here, reminiscing).

So, my biggest issue here is with taking numbers out of sterile scenarios and trying to use them to create other stats and figures. Where does this 7W figure keep coming from, anyway? It's a reasonable number, sure.

But let's also consider that: the car has complete control over when it wakes up and recharges the battery. That means there's no need for it to go to a low SOC on the 12v battery, ever. Since SOC is very accurately tracked by near-rest voltage level, it's pretty easy to say "oh, 12.25v? yeah we'd better wake up and charge that".

What would be great to see is some battery-monitor stats/logs with a knowledge of what I've gone over before - regarding how/when it charges and such. Maybe try and get a current reading on the battery. See what the draw is like while it's asleep. See how low the voltage goes before the car decides to kick in and charge it. Voltage maps fairly cleanly to SOC - 12.0v is quite low (near 0%) and 13.0v is quite full (near 100%). So, see what the voltage is over time... how badly is it really being beaten up?

Great write up

 

[Tjhappel]

Ok this is an interesting read from a technical point of view. But can I add one thing. The 12V battery being used is nothing different than one you can typically buy in an ICE car. Now I am not saying it is being treated in the same fashion but the expected life of the average car battery is four to six years. The longer being what I have been used to. So in that respect with the amount of 12v battery replacement complaints 2 years is far too soon to wear it out. Now it is not your fault as the customer to expect better and its also not your fault as a customer that the model 3 is killing these 12v batteries quicker. Unless there is a large product recall due on the 12v batteries due to a batch being made bad. This actually goes against sustainability going through them at a higher rate creates waste.

In my opinion Tesla should replace these batteries at no cost. It seems quite obvious whether it can be fixed via a software update or not there is a common fault here. So yes demand a free replacement with proof from here that it is quite a wide spread issue.

How about a warning so we can actually fix them before they go bad??

 

[AlanSubie4Life]

It completely lines up with my observations as well - the car sleeps peacefully for hours and hours until I wake it, and generally for no other reason.

Looks like it'll probably wake up once or twice a day.

also, what's up with the steps in the Y axis? 9.0v (+2) 11.0v (+1) 12.0v (+1) 13.0v (+2) 15.0v...

Probably a non-linear scale just to make it easier to see the regions of interest (counteracts the voltage vs. capacity curve which is somewhat non-linear).

Your voltages look a bit different than mine, presumably due to the different battery type. That may also alter the amount of time between wake/sleep cycles. I'm curious what the longest sleep cycle you can get is. The longest I've seen is about 24 hours.

 

[FalconFour]

I'm curious what the longest sleep cycle you can get is. The longest I've seen is about 24 hours.

Well, I'm probably not going to be able to get you that, because I end up using the car at least once a day But it's a stark contrast to what you posted earlier, where it was waking up at least once every hour (just on the last page)... really just posting mine in response to that, making sure I'm not crazy in seeing that mine only wakes up when I make it wake up.

 

[thewallaby]

I think the only solution would be that Tesla had a parallel charger to the main one or an inverter that topped off the lead battery when charging the vehicle. On my ICE i have a coupe heater that also tops the battery every time i plug it in overnight in the winter. It cannot be so hard. Or even a drop down transformer so when the lead is too low to top off from the main battery. I know that most of you will press the fact that you need this and that special equipment but the man wants to go to Mars in 2 years i bet he can fix that in a weekend...
Also i do not get why have a 1000 pounds main battery and skimp the weight on the 12v when you 1. 90% of EVs have issues with them and 2. you have the space and power in the frunk to accomodate a much larger.
All my ICE cars had from 90-120A 12v batteries. Even the hybrid i had until last August it had a 95A battery.... what a place to save weight and money... safety.
Also why not pick a standard 90A gel battery that will last longer, will be easier to acquire, will be cheaper to produce than a special one and anyone could do it themselves by visiting their near auto shop. I know that they did not do anything on the facelift 2021 but i truly hope they make that change in the future, independently of the software patches or not.

 

[iwannam3]

Did a Y test drive and picked up an $85 at Tesla service. No core charge!

 

[AlanSubie4Life]

Well, I'm probably not going to be able to get you that, because I end up using the car at least once a day But it's a stark contrast to what you posted earlier, where it was waking up at least once every hour (just on the last page)... really just posting mine in response to that, making sure I'm not crazy in seeing that mine only wakes up when I make it wake up.

Yeah that issue was caused by Stats, which I have to stop using now. It hasn't always been this way, but apparently it is now. The developer says it is normal. Oh well. Have to dump the 3rd party app, though I liked opening my frunk without using my phone.

The overall pattern I see when Stats isn't involved is consistent with my prior posts of battery drain and how much the 12V gets cycled. (The answer is: a lot!)

 

[Phlier]

I don't think they are screwing it up, really. My contention is that they are just using the 12V battery too much. Much more than a regular ICE vehicle, when you work out the total energy pulled from the battery, in typical conditions.

Can't work miracles. If you use the 12V battery a lot, even if you charge and discharge it perfectly and very mildly, with shallow cycles, it still wears it out. Entropy!

So, my claim is it's probably not really the fault of the 12V battery treatment, really. It's more fundamental. They need to use it less (which is actually a much easier problem to solve than inventing a 12V lead acid battery that lasts forever)!

All the other manufacturers have already solved this problem (except BMW probably)! No reason why Tesla cannot. Get it to under 1W when sleeping and unattended. Not really a difficult job. The battery monitor uses 12mW max and you can communicate just fine with it over Bluetooth. That is 500x less power than 6W. They can wake up periodically and use the main battery however they wish (though that could be more efficient too!). But a fire hose of 5W of power while asleep is just really hard to accommodate & recover from - and it forces more frequent wake ups to top off the 12V - topoffs which are super inefficient periods (12500x more than 12mW, though about 70% of that power is pouring into the 12V battery, probably - 95% of which is recoverable, probably), and add insult to injury.

Alan, once again I find myself agreeing with your post, but there is something that we should probably discuss... in passing, at least.

I'm old. And I've lived in the desert for the vast majority of my life. Put the two together, and you have the perfect recipe for being a major consumer of vehicle batteries.

Yet in all my years, I've never seen a car lead/acid battery just out and out fail like we've seen with so many Tesla lead/acid batteries. The typical failure mode I've seen is that the battery just can't contain as much energy as it did when it was new, nor can it deliver that energy at the same rate. In a lot of the failures we've read about here (and other places on the 'net), people explain that their battery failed with a large bulge in it, and with a strong sulfur smell. The result being a battery that was *completely* dead. Not reduced capacity, not reduced ability to deliver energy, but doornail dead.

I can see Tesla using the battery outside of the battery's design parameters, but to me, that would just mean premature degradation of the battery, and not an out-and-out dead short, failed battery.

Sure, you also do hear of guys reporting that they got the "replace 12v battery soon" message, along with batteries that have shown "normal" failure modes of reduced capacity and reduced ability to deliver energy. But the rather large amount of posts by people with failed batteries is just a bit suspect.

I have no proof of this, but to me this reads as a rather large batch of bad batteries produced by the OEM.

Even if Tesla hasn't been using the 12v battery correctly, I think the OEM needs to man up a bit here.

 

[Phlier]

The 12V battery being used is nothing different than one you can typically buy in an ICE car.

Please don't take this as me just being pedantic to be a jerk, but there is a pretty significant difference between the Tesla 12v battery and a typical ICE 12v battery.

The battery used in Teslas is a "Deep Cycle" battery, whereas normal ICE vehicle batteries are designed to deliver a huge amount of starting current for a short period of time, deep cycle batteries are not designed to handle large amounts of current demand, and instead are designed to hold a large amount of total energy, which is delivered at a slower rate.

 

[Daniel in SD]

Alan, once again I find myself agreeing with your post, but there is something that we should probably discuss... in passing, at least.

I'm old. And I've lived in the desert for the vast majority of my life. Put the two together, and you have the perfect recipe for being a major consumer of vehicle batteries.

Yet in all my years, I've never seen a car lead/acid battery just out and out fail like we've seen with so many Tesla lead/acid batteries. The typical failure mode I've seen is that the battery just can't contain as much energy as it did when it was new, nor can it deliver that energy at the same rate. In a lot of the failures we've read about here (and other places on the 'net), people explain that their battery failed with a large bulge in it, and with a strong sulfur smell. The result being a battery that was *completely* dead. Not reduced capacity, not reduced ability to deliver energy, but doornail dead.

I can see Tesla using the battery outside of the battery's design parameters, but to me, that would just mean premature degradation of the battery, and not an out-and-out dead short, failed battery.

Sure, you also do hear of guys reporting that they got the "replace 12v battery soon" message, along with batteries that have shown "normal" failure modes of reduced capacity and reduced ability to deliver energy. But the rather large amount of posts by people with failed batteries is just a bit suspect.

I have no proof of this, but to me this reads as a rather large batch of bad batteries produced by the OEM.

Even if Tesla hasn't been using the 12v battery correctly, I think the OEM needs to man up a bit here.

I agree the type of failures is abnormal. Of course the usage is also abnormal. Most ICE batteries hardly get cycled at all.
A hypothesis I like is that to save money on AGM batteries Tesla used a custom design optimized for their use case and the common failure mode can't be detected in advance.