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

[Timbo2]

I try to understand what you mean by "load test the battery" ?

Just that. You can either run a resistive or electronic test to determine the capacity and internal resistance of the battery. However, if the 12V DC-DC is charging or active you won't get a good result.

The most common type now seems to be the electronic version which runs some kind of magic PWM or something and will calculate remaining life based on what it reads and the internal resistance.

Digital 12V Battery Tester - Schumacher Electric

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Old school runs a big resistor.

100 Amp, 6/12V Battery Load Tester

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[Watts_Up]

Just that. You can either run a resistive or electronic test to determine the capacity and internal resistance of the battery. However, if the 12V DC-DC is charging or active you won't get a good result.

The most common type now seems to be the electronic version which runs some kind of magic PWM or something and will calculate remaining life based on what it reads and the internal resistance.

Digital 12V Battery Tester - Schumacher Electric

Looking for a Digital 12V Battery Tester? Visit Schumacher Electric for portable jump starters, battery starters, EV chargers, and more.

www.schumacherelectric.com

Old school runs a big resistor.

100 Amp, 6/12V Battery Load Tester

Amazing deals on this 100 Amp 6/12V Battery Load Tester at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Does those tester should be used when the battery is diaconnected from any load?

Note: I would recommend installing a 12 V monitor, so you can check on your phone the status of your 12 V battery.
You get a 24 hour graph, so you can see when the battery get charged and see the attery getting discharge otherwise.
The battery voltage after been charged is around 13.5 V and the battery get charged around 12.5 V after two days.
So 1 V / 48 hours = 20 mV / hour.

 

[Timbo2]

Does those tester should be used when the battery is diaconnected from any load?

Note: I would recommend installing a 12 V monitor, so you can check on your phone the status of your 12 V battery.
You get a 24 hour graph, so you can see when the battery get charged and see the attery getting discharge otherwise.
The battery voltage after been charged is around 13.5 V and the battery get charged around 12.5 V after two days.
So 1 V / 48 hours = 20 mV / hour.

On an ICE vehicle you can run the resistive tester to check the alternator.

Otherwise you'd run both testers with the car off. Small accessory loads will skew the results, but not badly. The issue with our cars is the the charging.

I should add the loading is important. You can have batteries that have good solid voltage when measured, but under any kind load will drop down immediately. That's the downside to just monitoring voltage.

 

[STS-134]

I would recommend installing a 12 V monitor, so you can check on your phone the status of your 12 V battery.

Typically the battery voltage will be between 12.5 V and 13 V when the car is sleeping.
When driving, the Inboard DC/DC inverter get activated to avoid getting the 12 V battery to be discharged.,
and the battery voltage will then be around 13.5 V.
When the car is sleeping and the Inboard DC/DC inverter is charging the battery, the voltage is around 14.5 V,
After charging, the battery voltage is around 13.5 V

For what I observed, when the car is sleeping for few days, the battery voltage is dropping from 13.5 V to 12.5 V in about two days.
When reaching 12.5 V, the Inboard DC/DC inverter get activated and charge the 12 V battery for two to three hours.

Interesting device but I don't think the voltage of the battery has anything to do with its state of health.

 

[Timbo2]

Interesting device but I don't think the voltage of the battery has anything to do with its state of health.

It will tell you state of charge. As it dies you may not be able to fully charge it or alternatively your car may come on frequently to top it off. With the continuous 12V monitoring you will likely see that. But just monitoring voltage isn't a complete solution.

As the plates sulfate up internal resistance goes up making that one of the better ways to monitor health. These new electronic testers will test for that. I'm not sure how much I trust the absolute readings they provide, but I'm more interested in change over time.

 

[PianoAl]

I had Tesla replace mine at 2.5 years and 45k miles. When I set up the appointment, they had a charge (cost) for it, but ended up doing it for free. I assume they found something wrong with it.

 

[eglove]

Just had mine replaced at 15,300km. (2021 M3 LR) Having a ranger come to you is so awesome haha

 

[texas_star_TM3]

I had Tesla replace mine at 2.5 years and 45k miles. When I set up the appointment, they had a charge (cost) for it, but ended up doing it for free. I assume they found something wrong with it.

Just had mine replaced at 15,300km. (2021 M3 LR) Having a ranger come to you is so awesome haha

was something wrong with it? or are we now down to replacing 12V batteries annually as preventative maintenance?

 

[texas_star_TM3]

I had Tesla replace mine at 2.5 years and 45k miles. When I set up the appointment, they had a charge (cost) for it, but ended up doing it for free. I assume they found something wrong with it.

I'm approaching the 3yr mark and nearly 30k miles... not having any longer roadtrips planned throughout the summer ... so I'm waiting until the fall to get it replaced before upcoming trips where a dead battery would be a nightmare (or it fails and is under Tesla warranty before then)

 

[RayK]

I'll be at 4 years this July and currently at 23.5K miles with the original battery. Going on a trip up to Ashland, OR next month so I'm seriously considering proactively replacing the 12V battery even though I've had absolutely no problems with it.

 

[Watts_Up]

I'll be at 4 years this July and currently at 23.5K miles with the original battery. Going on a trip up to Ashland, OR next month so I'm seriously considering proactively replacing the 12V battery even though I've had absolutely no problems with it.

Try getting the battery to be replaced before the warranty expired.

 

[STS-134]

Try getting the battery to be replaced before the warranty expired.

Will they replace it under warranty if it's not actually failed yet?

 

[boiler81]

Replaced mine pro-actively on my M3D prior to 2nd cross country winter trip in Dec. 2020 (@ approx. 39K miles). Had heard of folks being stranded without warning, so pick-up replacement on my nickel from Tesla service and installed myself...cheap insurance.
The OEM M3 battery continues duty in my "garage queen" 2006 Miata as it was a direct fit, and I keep it on a trickle charger.

 

[PianoAl]

Will they replace it under warranty if it's not actually failed yet?

They did for me, but I'm hypothesizing that they found a problem with it. I'd have asked about that, but it had been a long day of fixes, and I was eager to drive the four hours home.

 

[android04]

Will they replace it under warranty if it's not actually failed yet?

No. But the battery costs $85 if you want to buy it and replace it yourself. Or about $135 to pay them to replace it.

 

[SilverString]

No. But the battery costs $85 if you want to buy it and replace it yourself. Or about $135 to pay them to replace it

Replacement for my 2019 MS was somewhat more. I'm going on a multi-thousand mile road trip soon and don't want any unpleasant surprises in the mountains. My car is three years old with 50K miles and Mobile Service said it was in the "gray area" as to whether to replace.

 

[android04]

Replacement for my 2019 MS was somewhat more. I'm going on a multi-thousand mile road trip soon and don't want any unpleasant surprises in the mountains. My car is three years old with 50K miles and Mobile Service said it was in the "gray area" as to whether to replace.

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Yeah, the Model S is more expensive probably because it's an AGM battery. I'm pretty sure the Model 3/Y lead acid is not AGM.

 

[Austindude]

I replaced mine proactively late last year, which was at about 3 years. I plan (if I still have the car) to replace it every 2 years since its only $85 for the part, and $129 total installed in my driveway by tesla.

I did it proactively after reading all the 12v threads here. Its cheap enough that its consumable on our cars.

Proactive battery replacement, I'm with you. After spending close to $60K on the car I felt proactively replacing the 12V battery was a good idea. So how much was it worth to me to not get stranded somewhere? Well for me the risk of not getting stranded is worth much more than the cost of an early battery replacement. Let's say I replaced the battery at 2 years but I could have gotten another year out of it. OK so I threw away the value of another year of the battery, so what? In dollars maybe I wasted half the cost of the replacement (around $65)? Hell, I've spent more than that on some dumb after market cosmetic upgrades! When it comes to my dollars it's always a decision based on risk reward and for me I'm proactive when it comes to the car.

 

[SilverString]

Yeah, the Model S is more expensive probably because it's an AGM battery. I'm pretty sure the Model 3/Y lead acid is not AGM.

Seems like a good price for delivering it and installing it, but I was unable find a US price on an AtlasBX U1 AGM. The tech also told me if that if my car did not already have this battery, which is yellow, then it would be a red battery, and they would make a configuration change in the car, otherwise the battery would only last about a year... never heard that before.

 

[jwharnish]

I'll be at 4 years this July and currently at 23.5K miles with the original battery. Going on a trip up to Ashland, OR next month so I'm seriously considering proactively replacing the 12V battery even though I've had absolutely no problems with it.

How often did you replace batteries with your ICE cars. I replaced every 4-5 years routinely to avoid issues, even though I had no problems.
Your car with 23.5K miles in 4 years, average 6K/yr does not see a lot of trips and charging cycles. I'd replace it to be on safe side for next 4 years. No reason to wait for a failure.