"Proactive" 12v battery replacement - good idea or overkill?

[mrau]

Unless you are monitoring this constantly and see how often your car is charging your battery, no one measurement means anything

The monitor and app do all the work of gathering data, I just scroll through the day graphs when I want. It is an easy way to see the voltage of your 12v battery since there is not a voltmeter on the dash/screen. I do think Tesla is doing a good job and I still have my original 3 1/2 year old battery, If it last through the warranty period (6 more months) then I will replace it on my own dime before winter. I think 4 years on a 12v battery is pretty good.

 

[Watts_Up]

The external battery monitor just monitors the voltage of the battery, it is not a charger. It plots all the info on a daily graph when you synch monitor with your phone. It is handy for seeing when the car sleeps (since voltage slowly drops) and when it wakes up (voltage jumps and remains higher). Generally the car wakes up about once every 24 hours if it has not been driven. If voltage resting level is below 12.3 it may be indication of a weakening battery.

Here is what a non-driving day looks like when car awoke about 1800 hrs (6 PM) with a spike to 14.5 volts.

@mrau I have the same 12 V Battery Monitor, something I would recommend
to any EV owners (See in particular the Ioniq 5 battery problems)

When I am not driving for few days, I noticed that my 12 V battery
get charged by the inboard DC/DC inverter every 2 days
for about 2 hours when the voltage reaches 12.5 V:

But recently I noticed that the battery was getting discharged very fast in about 8 hours instead of 48 hours.
This occured for one or two days and then everything went normal again.

I was thinking that it was time to change my battery who seems not able to keep the charge,
but the following days the battery was working as usual and getting recharged only after 2 days.

And two weeks later I noticed the same discharge and recharge every 8 hours for a full day,
and then the car went sleeping for 2 days without having the inboard charger for 2 days:

Can you find any explanation for this strange behaviour?

My car was parked at home so Sentry was not running, and the car was sleeping,
I have an LED connected to the auxiliary plug so I can check is the car is sleeping.

 

[gearchruncher]

This is how you will drive yourself nuts trying to track health via voltage. You have no idea of the load on the battery, so you don't know if it's dropping fast because of load or because of health. We don't even know this behavior is strange. Maybe the car does some sort of maintenance every now and then that keeps the HV contactor on and causes quicker 12V drain.

Any voltage measurement is just going to cause you to question if it's the battery or just Tesla SW doing what it does.

 

[Watts_Up]

This is how you will drive yourself nuts trying to track health via voltage. You have no idea of the load on the battery, so you don't know if it's dropping fast because of load or because of health. We don't even know this behavior is strange. Maybe the car does some sort of maintenance every now and then that keeps the HV contactor on and causes quicker 12V drain.

Any voltage measurement is just going to cause you to question if it's the battery or just Tesla SW doing what it does.

I could install an Ampmeter to determine how much energy is sent to recharge the battery and how much is then used.

I suspect that the propulsion battery management was doing so kind of internal house cleaning?
Would the battery cooling pumps or fans be running for about eight hours straight without making any noticeable noise?
There was no real weather temperature change, I didn't touch the car like opening a door or tried to connect to the car with my phone.

Other possibilities would be the CPU was dumping some FSD content but doing this for eight hours continuously several time is difficult to explain?
There was no software update that I was aware at that time and even so this would not take that much time.

I was wondering if any other user who installed this type of battery monitor ever noticed such type of unusual behaviour?

 

[mrau]

@Watts_Up I have not seen that type of activity on my battery monitor. If the car is parked for a couple of days then it usually wakes up once a day for about 20 minutes. The cabin overheat protection does not come on since car is parked in a garage.
Not sure what is happening with your car but it does seem to happen when voltage hits a certain level and the drain rate is fairly steady.

 

[FloridaGary]

The only "major" service issue I have ever had with my 2018 P3D is that I had to have the 12v battery replaced after about 2 1/2 years. Even though it was covered under warranty, I consider it a major issue because it rendered the car undriveable and it had to be towed. At that time, there was no warning that the battery was weak. One day, the car just would not power on and I had to have it towed to the nearest SC.

My question is, is it a good idea to have the 12v battery replaced periodically even if there is no sign of a problem? If so, when would you have it replaced? Every 2 years? Every 18 months?

Just curious what other Tesla Model 3 drivers are doing in regards to 12v battery replacement. Thank you!

Joebruin77

I also had the battery failure on my 2018 Model 3 after 2-1/2 years. Telsa replaced it in my garage, but I have a reminder on my phone set for 1-1/2 years to replace it with the OHMMU Lithium battery since the car will no longer be under warranty after 4 years.

 

[Theone8181]

I also had the battery failure on my 2018 Model 3 after 2-1/2 years. Telsa replaced it in my garage, but I have a reminder on my phone set for 1-1/2 years to replace it with the OHMMU Lithium battery since the car will no longer be under warranty after 4 years.

Will li-ion work? Didn't think it was a straight swap?

 

[FloridaGary]

Will li-ion work? Didn't think it was a straight swap?

Yes, it will definitely work. You can find examples on youtube of tesla owners installing them.

 

[gearchruncher]

Yes, it will definitely work. You can find examples on youtube of tesla owners installing them.

You can also find threads here where they throw alerts after Tesla updated their software and see a Lithium battery as a "broken" 12V Lead Acid, because it is. Right now Ohmmu is not selling batteries until they can figure out how to fix this.

Longer term Ohmmu experiences?

Hi Looking at possibly buying an Ohmmu lithium (LiFePO4) battery to replace the OEM one in my Model 3. The car is approx 18 months old and from what I can see from stats it has started waking up to top up the 12v battery every 24 hours, so I don’t think it’ll be too long before it says it needs...

teslamotorsclub.com

 

[RayK]

$85 for the battery, $34.50 for the labor to r/r it and CA/local taxes of $7.75. Yes I could have done it myself and saved the $34.50 but it's cheap insurance in case something goes wrong with it. They can't blame me for anything I might have/have not done properly.

I'm pretty sure that I paid over $130 for the last BMW battery I bought 10+ years ago, purchased over the counter from BMW and installed in the trunk myself.

edit: Changed from 25+ to 10+ years ago. Sorry, brain fart.

 

[KuramaKitsune]

$85 for the battery, $34.50 for the labor to r/r it and CA/local taxes of $7.75. Yes I could have done it myself and saved the $34.50 but it's cheap insurance in case something goes wrong with it. They can't blame me for anything I might have/have not done properly.

I'm pretty sure that I paid over $130 for the last BMW battery I bought 25+ years ago, purchased over the counter from BMW and installed in the trunk myself.

misread that as 85 for the battery AND 130 for the work

 

[danarcha]

Will li-ion work? Didn't think it was a straight swap?

The new Tesla Li-ion battery is not a straight swap. There are some hardware changes required, but the Ohmmu Li-ion battery will work in older Model 3s.

 

[kayrish]

Just wanted to provide some input on 12V battery monitors:

While it may not be the go-to tool in assessing the health of your 12V. It can certainly help diagnose unusual behaviour which are signs of a failing battery. I've been having all sorts of sleep/wake issues where the car is waking up 100 times a day or so since Feb 22 (there was no update installed the day before to trigger this) . I dont have a single 3rd party accessory or 3rd party apps connected, and all the usual features that keep the car up have been disabled.

You can read more about my issues here: Model 3 Multiple Issues

While it's not yet proven that my 12V is causing the issue, I recently installed a 12V monitor only to see all kinds of voltage drops and spikes. It seems like the car has been frantically waking/sleeping to keep the 12V topped up due to rapid discharge of the battery. It is either a sign of my 4 year old original 12V failing, or abnormal parasitic drain from a software bug/faulty hardware component.

What's more interesting is this issue arose when the car had been left for 4 months, only being charged as the HV battery drained. From a physics standpoint this is in line with a use-case that would cause sulfation as the car wasnt waking up long enough to free sulfate build up.

Do you think this makes sense... I've been troubleshooting for months now so I tend to tunnel vision when things add up like this.

Here is what my graph looks like (the periods where it holds voltage indicate not sleeping, or a drive:

 

[Flybyglass]

Just wanted to provide some input on 12V battery monitors:

While it may not be the go-to tool in assessing the health of your 12V. It can certainly help diagnose unusual behaviour which are signs of a failing battery. I've been having all sorts of sleep/wake issues where the car is waking up 100 times a day or so since Feb 22 (there was no update installed the day before to trigger this) . I dont have a single 3rd party accessory or 3rd party apps connected, and all the usual features that keep the car up have been disabled.

You can read more about my issues here: Model 3 Multiple Issues

While it's not yet proven that my 12V is causing the issue, I recently installed a 12V monitor only to see all kinds of voltage drops and spikes. It seems like the car has been frantically waking/sleeping to keep the 12V topped up due to rapid discharge of the battery. It is either a sign of my 4 year old original 12V failing, or abnormal parasitic drain from a software bug/faulty hardware component.

What's more interesting is this issue arose when the car had been left for 4 months, only being charged as the HV battery drained. From a physics standpoint this is in line with a use-case that would cause sulfation as the car wasnt waking up long enough to free sulfate build up.

Do you think this makes sense... I've been troubleshooting for months now so I tend to tunnel vision when things add up like this.

Here is what my graph looks like (the periods where it holds voltage indicate not sleeping, or a drive:

View attachment 813858

Replace the battery if it's 4 years old is a good start.

 

[kayrish]

Replace the battery if it's 4 years old is a good start.

Of course, just never got any alerts. Tesla had the car at their shop four times for the issue. Surprised it was glossed over.

 

[KenC]

Just wanted to provide some input on 12V battery monitors:

While it may not be the go-to tool in assessing the health of your 12V. It can certainly help diagnose unusual behaviour which are signs of a failing battery. I've been having all sorts of sleep/wake issues where the car is waking up 100 times a day or so since Feb 22 (there was no update installed the day before to trigger this) . I dont have a single 3rd party accessory or 3rd party apps connected, and all the usual features that keep the car up have been disabled.

You can read more about my issues here: Model 3 Multiple Issues

While it's not yet proven that my 12V is causing the issue, I recently installed a 12V monitor only to see all kinds of voltage drops and spikes. It seems like the car has been frantically waking/sleeping to keep the 12V topped up due to rapid discharge of the battery. It is either a sign of my 4 year old original 12V failing, or abnormal parasitic drain from a software bug/faulty hardware component.

What's more interesting is this issue arose when the car had been left for 4 months, only being charged as the HV battery drained. From a physics standpoint this is in line with a use-case that would cause sulfation as the car wasnt waking up long enough to free sulfate build up.

Do you think this makes sense... I've been troubleshooting for months now so I tend to tunnel vision when things add up like this.

Here is what my graph looks like (the periods where it holds voltage indicate not sleeping, or a drive:

View attachment 813858

Any electrically-related wonkiness, always check the 12v.

 

[texas_star_TM3]

Replace the battery if it's 4 years old is a good start.

yeah... once you are out of warranty and the battery didnt fail within the 4yr warranty period... I'd probably go for a pro active replacement after 4 yrs.

 

[threeputts]

Another data point: I have mobile service scheduled to come out and proactively replace the 12V in our LR MY next week - estimate total is $110.90.
$26 for them to deliver and install? Sold.

 

[Theone8181]

Another data point: I have mobile service scheduled to come out and proactively replace the 12V in our LR MY next week - estimate total is $110.90.
$26 for them to deliver and install? Sold.

Do they typically go yo any address? For me (although I'm in the uk), it would be handy for them to do it there rather than my house.

 

[SilverString]

Do they typically go yo any address? For me (although I'm in the uk), it would be handy for them to do it there rather than my house.

I have gel pack battery in my 50K miles three year old MS, and had it done yesterday at my home. Cost was $205 + tax which included labor in the amount of $40. Took the tech less than 10 minutes.