Has anyone replaced their 12V battery yet?

[dmurphy]

Not going to argue about AGM vs Lithium -- need more details to weigh in on that. The only point I wished to make is that the power source of the audio amp, whether Class A, AB, B or D can matter -- in fact it usually does. A Class D "digital" amp doesn't allow you to escape having a decent power supply. Consider the difference between a 16ohm load, 8, 4 and 1 ohm load (speaker) -- yes I have (fantastic) 1 ohm speakers. An audio amp is supposed to be have a particular VOLTAGE gain, regardless of load -- it is designed to be a voltage amplifier.

Consider an amp with a 28X gain. That means that, e.g. if you put in a 1V p-p audio signal, it may be expected to output a 28V output. And if it is rated at 100w into 8ohms, that would be 3.5A, 100watts = 28V * 3.5A (into 8ohms). Now instead of 8ohm speakers, connect 4ohm speakers, the same amp is now expected to deliver 7A while maintaining the 28V output, (and yes that means it is outputting 200w). Now connect up 1ohm speakers, the same setup is suppose to deliver 28A into the 1ohm loads to yield the 28V output, yielding 800watts. The point is that it really matters that not only is the amp up to delivering that kind of current, but the power supply (battery?) has to deliver high currents also. And it doesn't matter if the amp is "digital" or not. Those output MOSFETs still have to dump that kind of current into the loads while maintaining the specified voltage. The lower the frequency, the longer the MOSFETs have to keep dumping the current into the load. Amplifier class is about the conduction behavior of the output stage, the amplification required for proper output signals remain.

Whether some AGM is better than some lithium battery, it depends, but it certainly *can* matter. Many bad audio amps are bad because of their power supply. In this case, the audio amp being powered by the DC-DC converter, it shouldn't matter what the 12V battery is.

Agreed wholeheartedly. My point being, the waveform is generated by the Class D amp, not necessarily the input power source. So yes - the MOSFET needs the correct input voltage & current, but the idea that the li-ion battery can do so "cleaner" the AGM doesn't make a hill of beans of difference in our case here - the AGM is more than sufficient. Either the MOSFET gets what it to create the correct wave, or it doesn't. That's my argument with the digital class amp; no more, no less. I agree with you - the battery still needs to deliver plenty of current at the correct voltage. But the idea that the li-ion does so "cleaner" - behind a DC-DC converter, doesn't mean a dang thing in this application.

 

[neurocutie]

1) Everything is powered by the PCS. But the 12V battery serves to smooth out the power.
2) The PCS functions as a CV (Constant Voltage) power supply. It attempts to output a constant voltage, as long as the load is under 193 amps. The voltage is outputs varies from as low as 13.5 to as high as 14.5 depending on what part of the 12V battery charging regime the car is in.

It sounds like you are saying that the entire "12V" supply of the car *is* the "charging buss" of the 12V battery. If so, that's interesting, not sure it is efficient/smart. Basically it would mean that all of the 12V subsystems would often be getting 13.5-15V (and may draw upwards of 50-100A), when they are designed for a nominal 12V operation. Which then means that the 15-12V=3V*100A or 300watts of wasted power just to maintain this design of the 12V battery being charged directly by the PCS. It also means that each subsystem would like have independent voltage regulators to stabilize their supply because 3V swings in supply voltage are not going to be optimal for many circuits. Interesting... do you know how many additional voltage regulation circuits there are in the car?

 

[smatthew]

It sounds like you are saying that the entire "12V" supply of the car *is* the "charging buss" of the 12V battery. If so, that's interesting, not sure it is efficient/smart. Basically it would mean that all of the 12V subsystems would often be getting 13.5-15V (and may draw upwards of 50-100A), when they are designed for a nominal 12V operation. Which then means that the 15-12V=3V*100A or 300watts of wasted power just to maintain this design of the 12V battery being charged directly by the PCS. It also means that each subsystem would like have independent voltage regulators to stabilize their supply because 3V swings in supply voltage are not going to be optimal for many circuits. Interesting... do you know how many additional voltage regulation circuits there are in the car?

The 12V system of the Model 3 is not much more advanced than that of an average ICE car, with the exception of the e-fuses. In the automotive world, 12V means anything from about 10.5-15. This is because you need to recharge the 12V battery while you drive. Don't' forget, a full 12V battery is like 13.1 volts. And a 12V battery is essentially dead as 12V.

Every electronic device in a car has it's own additional voltage regulation. Especially since most electronics are actually running at 3.3 or 5v. Don't think of this as wasted power - since we don't know for certain what form of voltage regulation the devices in the car are using. The main computers are definitely using their own DC-DC switch mode converters, so they can work efficiently on any voltage. The power would only be wasted if Tesla was using linear regulators. I honestly doubt Tesla is using many - if any - linear regulators since they are so concerned about power efficiency.

For instance: VCFront has at least three switch mode converters. One is labeled "Hall 8V". The others are probably 5V and 3.3V. I couldn't find any linear regulators on the board.

 

[MattUNI]

My September 2018 Model 3 12V died, without warning, about 4 months ago in my employer's underground parking garage. Tesla roadside had to get it and tow it to a service center, where they had it replaced in about an hour. They said that they typically see 12v failures around the 18-24 month period of ownership.

I really would have loved to have received a warning before the failure, but alas, I did not. Here's to hoping for a warning before this next one fails.

 

[Davisj2077]

I just received a warning yesterday after only 611 miles on the car.

 

[XLR82XS]

I just received a warning yesterday after only 611 miles on the car.

Damn! How old is the car? Been sitting parked for extended time period?

 

[SDKoala]

Replaced the 12v battery on my Model S. Was told at the time that the battery powered the computer.

You joined on Sep 9, 2015 and this is your first post? That's some master level lurking. I'm impressed.

 

[gtmotor]

They are coming to my house tomorrow morning to swap it out for free. This is the first time I've used any sort of Tesla service and the process has been great so far. The service advisor told me that the Model S gives you upwards of 2-3 weeks of drive time once that warning appears however for some reason the Model 3 only gives you like 24-48 hours notice. He said if I see that warning again don't use the app but just call the service center to get someone out ASAP. Could be useful information for someone else here so you don't get stranded like I did.

 

[23adrock]

The bass improvement is no snake oil. It’s dramatic. Night and day. That’s not bias effect. I detailed my experience over at Model 3 subwoofer install.

Why does it work? I have no idea. But I’m glad it did, because I was tremendously disappointed in the premium Audio’s bass before the switch.

 

[smatthew]

The bass improvement is no snake oil. It’s dramatic. Night and day. That’s not bias effect. I detailed my experience over at Model 3 subwoofer install.

Why does it work? I have no idea. But I’m glad it did, because I was tremendously disappointed in the premium Audio’s bass before the switch.

No offense, but the only posts you've ever made are in support of the that expensive lithium ion battery you installed.

 

[Jeffrios]

... the Model 3 only gives you like 24-48 hours notice. He said if I see that warning again don't use the app but just call the service center to get someone out ASAP....

Good info on this. So basically, if I see the issue I'll probably just drive directly to my SC if under warranty, or go to Orielly or any place close by that sells a replacement.

 

[Autovoid]

I just received a warning yesterday after only 611 miles on the car.

I had a somewhat similar experience as you. My car was only three months old when my 12v needed to be replaced. I posted this on another thread from April 10, 2020:

I have been following the 12v battery related threads. Two days ago I received the notification, “Replace 12V battery soon.” I took delivery of my car on December 24, 2019. I barely have 3,000 miles on the car. I was able to schedule a service appointment for this morning. They just left my house after installing a new battery.

They told me that it’s not common to have a battery replacement this soon, but that it does happen. They added that it is nothing I am doing or not doing that caused it—just a bad battery. BTW, I charge my car at home using the Gen 2 mobile connector that came with the car. I connect it using a NEMA 14-50 plug that is on a dedicated 50 amp circuit.

The home service call was great. They asked if I had any other issues to address, fortunately I did not. They put air on all my tires and then they were on their way.

 

[Salted]

The bass improvement is no snake oil. It’s dramatic. Night and day. That’s not bias effect. I detailed my experience over at Model 3 subwoofer install.

Why does it work? I have no idea. But I’m glad it did, because I was tremendously disappointed in the premium Audio’s bass before the switch.

Do you mind telling us your 3's build date? I strongly suspect those who notice a difference with a lithium swap had borderline failing 12V batteries. From my searches many 2018 deliveries had drained (damaged) AGM batteries that wouldn't meet OEM spec or be adequate for audio needs. Those cars' audio would improve with any new-spec battery, regardless of chemistry.

 

[davidviolin]

I got a Dec '18 M3P+ and I just switched the 12v to the mountain pass 12v lithium. Its easier to change it when you have a RWD car than AWD car cuz the front motor gets in the way a little, but I saved 25lb of weight and the sound system sounds like it got a $5000 upgrade. The sound was always good, but now it is absolutely incredible. Well worth it. If your 12v dies, I would HIGHLY recommend switching to lithium. It will laster many times as long, sound is amazing, and it it saves alot of weight.

I want to note to the other skeptics here, that my old lead acid 12v was in fine condition, and there was no reason for me to change it other than to save weight. The sound system was a welcome and susprise side benefit. But now I would recommend it to anyone, main benefit is not weight reduction, but audio improvement.

 

[XLR82XS]

Anyone using Odyssey batteries? I've had good experiences with them in other ICE vehicles in the past.

 

[smatthew]

I got a Dec '18 M3P+ and I just switched the 12v to the mountain pass 12v lithium. Its easier to change it when you have a RWD car than AWD car cuz the front motor gets in the way a little, but I saved 25lb of weight and the sound system sounds like it got a $5000 upgrade. The sound was always good, but now it is absolutely incredible. Well worth it. If your 12v dies, I would HIGHLY recommend switching to lithium. It will laster many times as long, sound is amazing, and it it saves alot of weight.

I want to note to the other skeptics here, that my old lead acid 12v was in fine condition, and there was no reason for me to change it other than to save weight. The sound system was a welcome and susprise side benefit. But now I would recommend it to anyone, main benefit is not weight reduction, but audio improvement.

I'm reminded of people replacing the interconnects on their stereo with $500/ft wire and claiming they hear an improvement. Often we hear what we want to hear.

 

[davidviolin]

I'm reminded of people replacing the interconnects on their stereo with $500/ft wire and claiming they hear an improvement. Often we hear what we want to hear.

Sometimes, yes. Sometimes, no. I'm a professional musician so I do trust my hearing. There was no question in my mind of the difference. I guess you would have to test it out for yourself to hear the difference. But then again, like you said, often we hear what we want to so might not be a reason for you to even try.

I live in Atlanta and would be interesting if someone with the OEM battery wanted to do a comparison test.

 

[smatthew]

Sometimes, yes. Sometimes, no. I'm a professional musician so I do trust my hearing. There was no question in my mind of the difference. I guess you would have to test it out for yourself to hear the difference. But then again, like you said, often we hear what we want to so might not be a reason for you to even try.

I live in Atlanta and would be interesting if someone with the OEM battery wanted to do a comparison test.

Now that would be awesome to find out the results from. If you do that - can you find an "impartial observer" who doesn't know which car is which?

 

[davidviolin]

I would be happy to volunteer my car if anyone is in the ATL area and wants to compare.

 

[sduck]

Doing audio A-B tests are difficult in a car, although it would be kind of possible. The lack of volume numbers is a big problem - but you can count down or up from the extremes to match them. And you'd have to have identical EQ settings, and identical program material on flash drives or whatever - I wouldn't trust the streaming services or FM for this. And there would be no easy way to rule out cognitive bias - you're going to know which car is yours. You'd want at least one impartial observer.