12v battery issue, Tesla unsatisfactory response

[AlanSubie4Life]

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.

Oh, I agree, I'm sure there are plenty of bad batteries out there. Someone I know had theirs replaced after just a few months.

What is the failure rate? I don't know. How does it compare to other manufacturers? I don't know.

All of my discussion is more about the situation where the 12V goes bad (possibly for the lack of capacity or reduced CCA or whatever) after 2-3 years. And isn't bulging, etc. How much of a problem is this? I also don't know. My battery appears to be fine, after resolving the stupid Stats problem (by disabling Stats).

As far as the OEM owning up of premature failures - I suppose that is between Tesla and the OEM, since they're replacing the customer batteries for free (though obviously the inconvenience is the real cost here).

The battery used in Teslas is a "Deep Cycle" battery,

I don't know anything about deep cycle. How is the design different than a regular lead acid battery? The Model 3 battery is not AGM AFAIK, so that's not it.

It sounds like it is optimized for capacity and not current. I guess maybe somehow optimized plates for that? But how does that help how deeply it can be cycled?

Is 48Ah high for a battery that is the size of the one in the Model 3?

 

[thewallaby]

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 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.

What you describe here is Tesla using defect batteries for over 2 years without recalls hoping to get their cost covered by customers that drive more than 60k in the first couple of years and are out of warranty which for me is much worse than a software bug or a wrong capacity design... i think someone should start ringing the bells at Tesla and recall all those faulty batteries if that is the case.

 

[thewallaby]

I don't know anything about deep cycle. How is the design different than a regular lead acid battery? The Model 3 battery is not AGM AFAIK, so that's not it.

Most people that call that term have no clue what it means so dont sweat it too much. A deep cycle battery would be normally used in solar panel applications. Not in cars but they are popular in EVs because of 1. cost and 2. presumably low required peak capacity. But i fear that this is not the case with Tesla. This might be because the coil heater (or something else i have no idea what it can be) pulls huge amounts of energy from the battery something that simulates the same load as the starter motor in an ICE car. Then a deep cycle battery is a very bad combo. I am sure there is a reason they picked a DeepC battery but they might have missed a parameter that makes it unfit for those cars is all i am saying.

The catastrophic failure is most likely on the design of the batteries. If a DeepC battery is offloaded with a high current over a long period of time it will eat its plates like bread.

In short:
Standard Batteries: Huge load - No discharge under 70-80% over long periods is allowed. Low capacity (due to faulty alternator f.ex.) will mechanically damage the battery.
Deep Cycle Batteries: Low constant load - Allowed to discharge to single percentage and charge again. Large loads will mechanically damage the battery.

Here is a short explanation:

• A car's battery is designed to provide a very large amount of current for a short period of time. This surge of current is needed to turn the engine over during starting. Once the engine starts, the alternator provides all the power that the car needs, so a car battery may go through its entire life without ever being drained more than 20 percent of its total capacity. Used in this way, a car battery can last a number of years. To achieve a large amount of current, a car battery uses thin plates in order to increase its surface area.
• A deep cycle battery is designed to provide a steady amount of current over a long period of time. A deep cycle battery can provide a surge when needed, but nothing like the surge a car battery can. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly). To accomplish this, a deep cycle battery uses thicker plates.

 

[FalconFour]

This might be because the coil heater (or something else i have no idea what it can be) pulls huge amounts of energy from the battery something that simulates the same load as the starter motor in an ICE car. Then a deep cycle battery is a very bad combo.

Well, the good news is, I can tell you there's none of that going on in a Tesla. As I explained on page 14 (sigh), the car doesn't use the 12v battery for anything at all except for waking up from sleep mode. Also, there is no 12v-based heater on at least the 3/Y but I don't know how the S/X battery heater works -- on the 3/Y, it's heated using the motor as a heater and connecting coolant in series while bypassing the radiator. The highest 12v power draw in the system is the radiator fan (on full speed), followed by either the headlights or the power windows. None of which are involved when the car is asleep

In short:
Standard Batteries: Huge load - No discharge under 70-80% over long periods is allowed. Low capacity (due to faulty alternator f.ex.) will mechanically damage the battery.
Deep Cycle Batteries: Low constant load - Allowed to discharge to single percentage and charge again. Large loads will mechanically damage the battery.

...

Bang on with the difference between the two batteries. As best I can tell, there's nothing particularly special about Tesla's battery, though. Outwardly it just seems like a standard car battery that fits a standard car battery size, but who knows what's under the skin for Tesla's spec.

Anyway, something interesting I've found is that the car seems to keep the 12v battery at 14.4v all the time it's charging. So maybe people with 120v L1 charging are going to be in for a bad time...

Yesterday - charging from midnight to 5am-ish

Today - charging from midnight to 5am-ish again...

That can't be a good thing.

 

[AlanSubie4Life]

something interesting I've found is that the car seems to keep the 12v battery at 14.4v all the time it's charging. So maybe people with 120v L1 charging are going to be in for a bad time...

Probably something to do with the Ohmmu (or just chance for your particular capture). My car doesn't do that. Just leaves it at 13.3-13.4V when charging, unless the 12V needs charging.

I don't think L1 charging people have anything to worry about other than the poor efficiency and greater length of time that the charging circuitry (for the HV, not the 12V, though obviously 12V charging circuitry will also be on, just at maintenance level) is active.

 

[TSLA Pilot]

Given all this drama and angst, surely the smart minds at Tesla will find a way to dump that heavy, unreliable, and finicky, 12-volt battery completely, and soon?

Until then, perhaps they'll find a way to tap the HV pack to provide a tiny amount of 12-volt power, as a backup for when the current 12-volt battery decides to spontaneously fail.

This pretty much bricks the entire car so it needs to become a BIG DEAL at Tesla HQ, stat.

Come on Elon, get on it!

 

[thewallaby]

Well, the good news is, I can tell you there's none of that going on in a Tesla. As I explained on page 14 (sigh), the car doesn't use the 12v battery for anything at all except for waking up from sleep mode. Also, there is no 12v-based heater on at least the 3/Y but I don't know how the S/X battery heater works -- on the 3/Y, it's heated using the motor as a heater and connecting coolant in series while bypassing the radiator. The highest 12v power draw in the system is the radiator fan (on full speed), followed by either the headlights or the power windows. None of which are involved when the car is asleep

Bang on with the difference between the two batteries. As best I can tell, there's nothing particularly special about Tesla's battery, though. Outwardly it just seems like a standard car battery that fits a standard car battery size, but who knows what's under the skin for Tesla's spec.

Anyway, something interesting I've found is that the car seems to keep the 12v battery at 14.4v all the time it's charging. So maybe people with 120v L1 charging are going to be in for a bad time...
Yesterday - charging from midnight to 5am-ish
Today - charging from midnight to 5am-ish again...
That can't be a good thing.

Your charging shows 13.x V for the most part.... that is not good. And it is obviously a soft error if this is happening during charging sessions since it is capable of charging to 14.4v....
The guy that changed the battery on my Model S said it was a deep cycle one. Doesnt the model 3 have the same type?
Also if the only 'large' consumer is the cooling fans, don't they go under charging? If i understand correctly L1 charging will also charge the 12v battery?
Sorry for my questions i have had only a Model S previously and currently waiting on a new model 3 so i am learning each day

 

[iwannam3]

Given all this drama and angst, surely the smart minds at Tesla will find a way to dump that heavy, unreliable, and finicky, 12-volt battery completely, and soon?

Until then, perhaps they'll find a way to tap the HV pack to provide a tiny amount of 12-volt power, as a backup for when the current 12-volt battery decides to spontaneously fail.

This pretty much bricks the entire car so it needs to become a BIG DEAL at Tesla HQ, stat.

Come on Elon, get on it!

They have been having 12 volt battery issues on all the vehicles since the earliest S. The Roadster used the main battery for 12 vdc, but that was quickly changed to a lead acid 12 v battery. There must be some reason to sacrifice the 12 v battery to gain more efficiency in the main battery pack. Pulling a continuous trickle charge would require the contactors to be closed and battery management system to be operating. No sleeping. They have the smarted Li battery guys in the world, they must have skipped the obsolete lead acid class in grad school.

 

[scottf200]

Your charging shows 13.x V for the most part.... that is not good.

Your comment about 13.x V not being good is based on what?!? Other sources say 13.2-13.4 is good.

I monitored the 12v battery voltage during an OTA update

Multi-stage Battery Charging -- A typical 12-volt lead-acid battery must be taken to approximately 14.2-14.4 VDC before it is fully charged. (For 24 volt systems, double these figures.) If taken to a lesser voltage level, some of the sulfate deposits that form during discharge will remain on the plates. Over time, these deposits will cause a 200 amp-hour battery to act more like a 100 amp-hour battery, and battery life will be considerably shortened. Once fully charged, marine batteries should be held at a considerably lower voltage to maintain their charge - typically 13.2 to 13.4 volts. Higher voltage levels will "gas" the battery and boil off electrolyte, again shortening battery life.

 

[FalconFour]

Your charging shows 13.x V for the most part.... that is not good.

Where are you getting that? Here's an annotated chart...

It just hangs out at 14.3~ish volts the whole time it's charging, then bonks down to 13.3v again.

In all my time watching this thing, I've never seen it go below 13.3v. It's always up there, and the battery monitor is always saying it's "charging" when it's clearly not -- it has no way to know since it doesn't have a current sensor. The car is also sleeping most of the time.

I think this is basically as perfect as it can get, aside from why in the unholy hell it's deciding to linger around at 14.3-4v with just occasional bips lower. It doesn't do that normally, when it's not charging but awake, so what's up with this? I will say it's not bad for lithium (at least, probably not bad), so that's nice. And it does behave incredibly well w.r.t. staying asleep and never waking unless I ask it to. So that alone is a good sign...

Meh, I did get another firmware update tonight, so l'll see if this behavior changes any.

On a loosely related note, this damn battery monitor app really chews through my phone battery in standby... real pain in the arse since my phone is all solar-charged off a setup from my back yard, and it's been cloudy lately! haha

 

[scottf200]

On a loosely related note, this damn battery monitor app really chews through my phone battery in standby... real pain in the arse since my phone is all solar-charged off a setup from my back yard, and it's been cloudy lately! haha

I had the problem for 1 day. Then I turned off all notifications within the app settings and only let it run in the foreground. It barely uses any phone battery now. I simply bring it up in my phone then walk near my house/garage door and it connects and downloads data.

 

[thewallaby]

I am assuming you guys are using a BT OBD and a cable daisy chain ? Care to share which one?

 

[scottf200]

I am assuming you guys are using a BT OBD and a cable daisy chain ? Care to share which one?

These are some of the fastest and most reliable from all I've seen/read.

I use the LX for my Android ecosystem. I think MX+ is useful for iOS/Apple ecosystems.

below via: OBDLink® MX+ | OBDLink® | OBD Solutions

 

[FalconFour]

I had the problem for 1 day. Then I turned off all notifications within the app settings and only let it run in the foreground. It barely uses any phone battery now. I simply bring it up in my phone then walk near my house/garage door and it connects and downloads data.

Android or iOS? Eh, actually I just fought and fought with it, Googled for how to prevent it from running in the background, found settings that I don't have access to (there is no option to "allow background activity" - dunno why not), and just kinda went around with a sledgehammer trying to kill every possible access it has and disabling every option, without uninstalling it. Utter madness, really hating this app so far. Submitted feedback about it, too. The battery drain and persistent connectivity alone (when it doesn't need to be - since it stores data on the device) is really a deal breaker for me.

 

[FalconFour]

I am assuming you guys are using a BT OBD and a cable daisy chain ? Care to share which one?

My latest posts have been using a bare-metal 12v battery monitor with its own Bluetooth interface. It doesn't interface with Tesla at all - it just records the voltage at its terminals and gives me that data, in a really neat chronological chart format with great resolution. Here's the toy I was recommended and bought: https://smile.amazon.com/QUICKLYNKS-Battery-Monitor-Bluetooth-Device/dp/B01MT4583U

Aside from that, I also have a Scan My Tesla setup, which involves three parts: (1) a breakout cable that creates an OBDII-like port from some CAN wires that were intercepted in the back seat (total hacker creation, not at all Tesla-sanctioned) - that's here (note the model years!): HRN-CT20T1 | Geotab GO | Geotab Adapters | GPS Fleet Tracking ~ (2) an OBDLink LX module - specifically the LX because none of the other features matter, but specifically an OBDLink because it's a high-performance module needed for the crazy speeds Tesla operates at ~ and (3) the Scan My Tesla app: scan my tesla (also just "scan my tesla" in the Google Play store). The good version is Android only.

 

[scottf200]

Android or iOS? Eh, actually I just fought and fought with it, Googled for how to prevent it from running in the background, found settings that I don't have access to (there is no option to "allow background activity" - dunno why not), and just kinda went around with a sledgehammer trying to kill every possible access it has and disabling every option, without uninstalling it. Utter madness, really hating this app so far. Submitted feedback about it, too. The battery drain and persistent connectivity alone (when it doesn't need to be - since it stores data on the device) is really a deal breaker for me.

Android. I created a post just now for you and others here: I monitored the 12v battery voltage during an OTA update

ASIDE: I really wish we could download the data from this app but I found no place it was being stored. If there are more tech folks then please look. Other apps save a 'database' of their collected info. It is probably there somewhere but in a compressed format or something.

 

[FalconFour]

Android. I created a post just now for you and others here: I monitored the 12v battery voltage during an OTA update

I've got to guess this is a limitation of being stuck on Android 8 - not too long ago it was proudly up to date, but then I've started to find more and more critical features I'm left behind on. Ugh. I thought my rooted-phone and alternate-ROM days were over Finally one thing I dislike about the Moto Z2 Force... oh well. No other phone has an unbreakable non-glass screen. All this Gorilla Glass crap and they all break, except this one.

I'm limited to these options...

Thankfully, it seems that my sledgehammer approach might've done the trick. Phone battery has held up well this morning. If this keeps up, I'm OK with it. Just wish I didn't need system-level brute force controls to get the app to stop being obnoxious. The dev should do that. Hopefully they improve it

 

[Wooloomooloo]

Sorry this is a thread bump. I've been having a VCFRONT error on my Tesla Model 3 since early November (VCFront_a180 and VCFRONT_a195) more than 50 errors over that time. While driving, while parked, while charging and most amusingly the car waking in the middle of the night, throwing errors and going back to sleep.

Anyway, long story short, the car has been the the Brooklyn, NY SC 3 times (first time they shrugged, 2nd time they replaced the DC/DC converter, 3rd time they blamed a 3rd party hitch (which I removed) and then when it persisted they asked me to bring it in again (best appointment was 7 weeks out, which was this Monday). In the meantime I replaced the 12v battery (3 weeks ago) out of desperation to see if it would fix the issue - it didn't.

Guess what? Today I get a call from another SC I took it to (I moved house) and then said the new 12v battery was the cause of the issue. What's more, I have to pay for a new Tesla OEM battery otherwise my warranty is voided and they won't investigate further.

I know this is all BS... but for now I am going to go along with things until it's fixed, then think about small claims and having them honor the warranty.

I guess I'm cancelling the solar roof and power wall

 

[Gasaraki]

Given all this drama and angst, surely the smart minds at Tesla will find a way to dump that heavy, unreliable, and finicky, 12-volt battery completely, and soon?

Until then, perhaps they'll find a way to tap the HV pack to provide a tiny amount of 12-volt power, as a backup for when the current 12-volt battery decides to spontaneously fail.

This pretty much bricks the entire car so it needs to become a BIG DEAL at Tesla HQ, stat.

Come on Elon, get on it!

The new Model S will be getting a Li-ion 12V battery.

 

[vickh]

The new Model S will be getting a Li-ion 12V battery.

I hope we/ Y is next. Don't like doing 3rd party solutions while under warranty...