12v Battery Options - Which is best?

[vcor]

Elon, there should be a manual override to open the frunk, if the 12v is dead.

Done! All new cars have a mechanical release. Described in the user manual. Older cars do not have this feature, although you can supply 12v through an external connector to power the car and electronically release via the FOB or from the screen. Again, it's in the user manual. On a 2012-2015 S, the external connector is behind the black oval, which snaps out.

 

[voltaholic]

Interesting.... I didnt know the Tesla supplied 12V battery had only a 12 month warranty. I think everyone is aware that all the replacement lead acid batteries are STARTER Batteries, right ? Starter batteries dont like being deep cycled. I'm sure 100 degree heat takes its toll on the lead acid types. Lithium , according to most all specs, tops out at about 160 degrees F. operating temp . I think the main concern is cost of the lithium replacement. So, why would anyone pay $439 for a lithium when they could buy an ohmmu alternative from LithiumMoto for $275 ???

 

[Cork]

No sense replacing it proactively. The car will let you know well in advance and you'll have numerous places to have it replaced even in the unlikely event that the error message comes on as soon as you set out. Replacing a 12v battery in a Tesla just because it's 4-years old is a lot like changing your motor oil and filter in an ICE car every 500 miles to "be safe" because all you're doing is wasting good oil and $$.

While I agree that it’s not wise to replace things before they die, you miss an important point here. Your Tesla does not necessarily tell you that the battery is in poor health. My model three battery suddenly died on me tonight, after service centers were closed, while it’s 20° outside, with absolutely no warning. And it gets better: the last action from the car was to roll down the windows. Tesla roadside assistance told me to tow it at my own cost with the windows down to an unsecured service center at night. This is the first time I’ve been thoroughly ashamed of Tesla.

 

[DGODERICH]

This has been covered ad nauseum and never has concrete evidence been presented that Lithium 12v batteries last any longer let alone the 3x longer required just to break even. Nor do they provide any advantages during their operational life over the $138 OEM battery. To the contrary, if you end up with issues with your 12v system while using an aftermarket 12v battery Tesla can void the warranty of related components citing the battery as the cause.

In a Tesla, all a 12v battery does is run small accessory devices like the MCU, headlights, interior lights, turn signals, etc. Compared to what the 12v battery is required to do in an ICE car (think starting the engine at very cold temps) to say this is "light duty" doesn't even fully capture the difference between these two applications.

Not to mention the Tesla keeps the battery at optimal SoC even when not running whereas an ICE car requires the engine be running to charge the battery via the alternator. Whenever this accessory isn't spinning the battery is discharging all-the-while. They sit for days sometimes discharging and then (in minus zero temps sometimes) are expected to provide an absurd amount of instant amperage draw to physically turn over a large internal combustion engine.

This is why the Cold Cranking Amps (CCA) is probably the most important metric when shopping for a new 12v battery... especially in cold climates. This metric means absolutely nothing in a Tesla to give you an idea how different of an application we're talking.

In an ICE car, there is no way to predict when that battery will suddenly not be able to provide the necessary juice to make the car run and it generally fails in the coldest and most dangerous of scenarios. There's too many variables and the ability to provide CCA tends to drop off rapidly once it nears the end of it's life. This isn't the case with a Tesla. The amps required to power headlights or a stereo are fractional by comparison and the car can monitor the health of the battery at a finite level. This battery health monitoring algorithm tends to err on the side of safety when it comes to warning of an impending failure and most can go weeks or even months once that warning has been issued. It's all-but-eliminated the potential for becoming stranded due to a 12v battery failure so for a few rare outlier cases.

Naturally, people are fearful of being "stranded" in the middle of the night, in the dead of winter and in the most inconvenient time possible. This is a good fear to have and it's based largely on our experience with ICE cars in which this fear is founded in reality. Manufacturers of 12v Lithium batteries prey on this fear since it's unrealistic in a Tesla. They try to get you to pay for something that will do you zero good in a Tesla and, if your fear is being stranded, could potentially even increase the odds of this happening due to the system not being able to properly monitor & manage the health of your 12v battery they way it was designed to do with the OEM chemistry.

The new cars will come with a lithium-based 12v battery but it will include thermal management & cell health management technology that was created for their battery packs. It will be properly engineered and accounted for within the Tesla electronics ecosystem unlike these Band-Aid slapped on Li-Ion 12v aftermarket "solutions" but I'm sure we'll see more and more people asking about it once the new cars start rolling out. Just know that there is a LOT of engineering resourced going into making that an OEM solution so it's silly to think you can just slap one in something as complex as a Tesla w/o any accounting for it via the firmware.

My last warranty replacement 12v battery (I'm still amazed Tesla will replace these under warranty when every other car manufacturer treats them as a "wear item" like the brake pads... I digress) they had a "newer & better version" which was similar in overall chemistry but from a new supplier. This required a change to my car's firmware to properly account for what was the same basic battery. Think about that for a minute. Do you seriously think that if changing to something as different as a lithium chemistry 12v battery you wouldn't need to account for a change that extreme in the car's management system if one is required for what basically amounts to the same battery? When I saw that even going from previous versions of the OEM battery to the newer versions required a firmware change to account for even these minor differences within the system it shed some light on how bad of an idea going with something as different in chemistry as a lithium battery for the 12v system is at any cost.

In short, anyone who says that a $400+ lithium 12v battery is an "upgrade" in any way for a Tesla is selling you snake oil. Don't fall for it.

tl;dr Stick with the OEM and file this conversation under crap not even worth wasting your time considering.

Exactly! Excellent assessment. Stick with OEM, that's what it was designed for!!

 

[DGODERICH]

No sense replacing it proactively. The car will let you know well in advance and you'll have numerous places to have it replaced even in the unlikely event that the error message comes on as soon as you set out. Replacing a 12v battery in a Tesla just because it's 4-years old is a lot like changing your motor oil and filter in an ICE car every 500 miles to "be safe" because all you're doing is wasting good oil and $$.

Come on people, listen to this guy. I thought Tesla drivers where more on the logical side. Don't fall for marketing scams. $439 battery are you crazy. Stick with $122 OEM Battery that is what the engineers designed it for. You don't need Lithium or high cranking amp battery. What are you cranking? The 12V in the Tesla is used to run electronics not to crank a engine over like in an ICE car

 

[Zuikkis]

Whenever someone is advocating Ohmmu batteries, I think it's a good idea to read this reddit thread first:

https://www.reddit.com/r/teslamotors/comments/xtone9

 

[Watts_Up]

Whenever someone is advocating Ohmmu batteries, I think it's a good idea to read this reddit thread first:

What specific comment do you have in mind?

I noticed complain about the > $400 cost and not be able to charge below freezing because there was no heating element.

Otherwise, what really wrong? Any major failure reported?

If you are not living in a freezing area, Li-Ion seems to be a better solution than acid batteries.

 

[maximizese]

Has anyone done a deep dive into why the 12V battery fails? At first I thought the OEM battery had poor quality control, but then it was said that Tesla's 12V system can be quite demanding on the battery (with dynamic software updates it's hard to pinpoint what's causing this or whether a patch corrected the problem). I know folks without Sentry Mode nor AP seem to get more life out of the 12V battery lasting anywhere between 2-8 years. Others have their 12Vs replaced like clockwork every 2 years. I know that was the case with the 12V on our old 2007 Lexus Rx400h; 25months later the battery was kaput. I had my 12V replaced preemptively by Tesla when they replaced the HV contactors, pyro fuse, and drive unit under warranty. Current battery was 2 years old when the 'low voltage battery needs replacing' warning came on but I've been driving with it over the last 11 months/12K miles...still getting voltage readings between 12.7-13.9V from the nosecone post.

Meanwhile the original 12V battery in our 2013 Fiat 500e is about to celebrate its 10th birthday after 84K miles. I would love some clarity on these batteries and systems because I'd hate to replace something prematurely, especially a battery.

 

[NewbyMaybe]

Clarity is in the eye of the beholder or no one really wants to study this.
Is the acid cooking out of the oem's? Sometimes. Does the ohmmu suck? Sometimes. I'm using the ohmmu because oem was not available due to location.

 

[NewbyMaybe]

Ideally an update would eliminate the 12v failure resulting in sudden bricking. But?

 

[Zuikkis]

What specific comment do you have in mind?

Well, just looking at the picture and those solder joints.. And the whole thing is held together with urethane foam?

 

[Watts_Up]

Well, just looking at the picture and those solder joints.. And the whole thing is held together with urethane foam?

I agree it looks a little bit sloppy, but is there any BMS or Cells failures reported?

About the soldered connections, here is what the user 'Tesla Tap' wrote:

While I've never used the Ohmmu battery, I don't see the concern over having soldered connections ​

over bolted connections. Soldered connections will last a lifetime. Bolted connections can come loose, ​

and having a bolted connection inside a battery would be a very bad design. ​

​

The recently added Bluetooth App provides certainly a practical diagnostic status,
but a graph showing the Soc time line would be very usefull and is missing

 

[Kaveman]

Coming up on 3 years with an OhmMU 12V. No Issues at all. Will get another when the 4 year warranty expires.
Just more gas on this dumpster fire thread.
Kaveman

 

[Zuikkis]

I agree it looks a little bit sloppy, but is there any BMS or Cells failures reported?

About the soldered connections, here is what the user 'Tesla Tap' wrote:

While I've never used the Ohmmu battery, I don't see the concern over having soldered connections ​

over bolted connections. Soldered connections will last a lifetime. Bolted connections can come loose, ​

and having a bolted connection inside a battery would be a very bad design. ​

​

The recently added Bluetooth App provides certainly a practical diagnostic status,
but a graph showing the Soc time line would be very usefull and is missing

Well, there obviously are also bolted connections inside Ohmmu battery, where the wires attach to the top cover..

 

[Watts_Up]

Well, there obviously are also bolted connections inside Ohmmu battery, where the wires attach to the top cover..

Thinking about it, the Li-Ion Cells in general have a negative and a positive terminal
where a wire can be bolted, however the wires could be also laser welded.

The main issue with the new type of Li-Ion batteries available, is that the BMS doesn't
always uses thermal probes to shutdown the charging when the ambient temperature
is below freezing, or if the Cells are overheating.

I assume that the Ohmmu batteries don't have this issue.

 

[Watts_Up]

Whenever someone is advocating Ohmmu batteries, I think it's a good idea to read this reddit thread first:

Thinking again about the Ohmmu battery, and in fact any commercial Li-Ion batteries now commonly available,
is what seems to be the lack of any internal protection provided with a fast fuse or DC circuit breaker.

For example, dropping a wrench tool on top of an acid battery would certainly creates a noticeable short circuit spark,
but in the case of an Li-Ion battery, the effect could be catastrophic because of the instant surge current available and possible risk of fire.

 

[Always Broke]

Ok I'm really going to add fuel to the fire. I have been working with batteries for over 40 years and have a lot of practical knowledge of the Battery industry from the inside.

1. Lithium Batteries , I would not recommend for that application for the money
2. AGM Batteries cannot be drained past 70% or they can loose up to 20% of there capacity each time you drain them down which is a cascading effect and the reason they are having to be replaced so often.
3. I would recommend a Dry Cell Traction Discover Battery EVU1A-A they have a much higher lead content so they can be drained down to 50% with no ill effects and only cost about 15-20% more than the regular AGM that you are buying plus they have a 60 month warranty. These in that application should last around 10 years or more.

* No i don't work for the company ( I work with Supercapacitors )

 

[islandbayy]

Ok I'm really going to add fuel to the fire. I have been working with batteries for over 40 years and have a lot of practical knowledge of the Battery industry from the inside.

1. Lithium Batteries , I would not recommend for that application for the money
2. AGM Batteries cannot be drained past 70% or they can loose up to 20% of there capacity each time you drain them down which is a cascading effect and the reason they are having to be replaced so often.
3. I would recommend a Dry Cell Traction Discover Battery EVU1A-A they have a much higher lead content so they can be drained down to 50% with no ill effects and only cost about 15-20% more than the regular AGM that you are buying plus they have a 60 month warranty. These in that application should last around 10 years or more.

* No i don't work for the company ( I work with Supercapacitors )

I'll add more fuel to the fire. Each and every failed Lead Acid battery in my MX and MS, has failed due to be boiled dry. Not due to deep cycling. I've tracked voltages, the cars do a good job of keeping them charged, too good to the point they are being maintained at too high of voltage and current. I was able to revive the last two I replaced by replenishing the acid. Took a few days of slowly adding it to the MS battery as it was an AGM, and the acid had to absorb back in through the tiny holes after I cut the glued cover off. The MX battery was one of the Korean Made, Atlas??? I think, can't remember exactly, but it was a SEALED, Flooded battery. Cut that sealed cover off, refilled and recharged, and got about a year of use out of both for various experiments and projects. I finally turned both in to AdvanceAuto for $10 gift card each (Along with about 30 more lead acid batteries I had).

I still keep an eye on the 12v system charging, tesla seems to have vastly lowered voltages over this past winter finally. Instead of charging them or keeping them maintained at 15+ volts, I'm noticing its keeping them happy at about 13.8-14, highest I've seen was about 14.5 volts now during times of high 12v system demand. The DC to DC appears to increase the voltage slightly to improve efficiency based on my observations.

Now, I had gotten tired replacing the 12v in my MS, so the last time around I did get an Ohmmu. Thus far, it is working flawlessly. It did fine through last winter, where we had a week of -10*F straight, and this summer with high temps.

 

[islandbayy]

Can't edit my post any longer, I've also changes MS & MX batteries for others locally, a couple dozen at this point. Nearly every single one was dry.

 

[Always Broke]

That is great information, the reason I recommend the EV from Canadian Energy is because it’s a dry cell technology and would handle the abuse quite a lot better and can’t freeze lol It’s I think actually manufactured but Discover Battery. Good Luck