My 2021 MY wouldn’t turn on

[ScoobyDoo82]

Weird story for ya.

Today I got home from work and relaxed for an hour before I had to leave for a doctors appointment.

I got into my car to leave for the doctor appointment and was sitting there looking at a blank (black screen). Car was completely dead.

The Tesla app was showing (my last recorded battery percentage from an hour ago at 33% and the ac on). However, interacting with the app didn’t change anything or wake up my car. It was completely dead.

I took the wife’s car to my appointment. When I returned home I removed the “blank” plug from the front of the front bumper to gain access to the emergency frunk pop release leads, grabbed one of my M12 Milwaukee batteries (I’m an electrician) and was able to pop the funk open. I removed the plastic cover from the section between the trunk and the firewall and tested the 12v battery. It was showing ~7 volts. Dead.

I called my local Tesla service center and they told me to have the car towed to them to have the vehicle looked at. My car is almost 3 years old with 60k miles - I knew I just needed a low voltage battery replacement. They said that once they receive my car it would be looked at and that if all ok, a new 12v battery would be installed. Estimated cost: $500 and 2-3 days!

I was like “you guys are crazy, can’t I just come by and buy a new 12v battery?”

They informed me that “it’s a safety issue and that swapping out for a new 12v battery is “not as simple as it seems” blah blah blah.

I took the wife’s car to the service center, got the exact OEM replacement battery for $93 (including tax) and replaced the battery myself.

The car came back to life with no issues.

Screw these service center guys for trying to make an extra 5x on somebody..

Rant over. Hope you enjoyed!

 

[Watts_Up]

... tested the 12v battery. It was showing ~7 volts. Dead.

I would strongly recommend to anyone getting a Bluetooth 12V Battery Monitor to control your battery voltage.
And in particular to check how often the 12V battery get recharged by the DC/DC inverter when your car is sleeping.

Typically the DC/DC inverter will run every two or three days for about two hours. If you notice that the DC/DC imnverter
starts running every day this is an indication that the battery cannot keep the charge and needs to be changed.

For info, when sleeping the battery voltage range is between 13.5 V and 12.5 V.​

​

The DC/DC inverter will be trigger when below 12.5 V.​

When the DC/DC inverter in running the battery voltage is 14.5 V.​

​

When driving the DC/DC inverter is running and is set to about 13.5 V,​

so the 12 V battery doesn't get discharged,​

I called my local Tesla service center and they told me to have the car towed to them to have the vehicle looked at.
My car is almost 3 years old with 60k miles - I knew I just needed a low voltage battery replacement.

They said that once they receive my car it would be looked at and that if all ok, a new 12v battery would be installed.
Estimated cost: $500 and 2-3 days!

I guess it was just an over the phone estimate.
The normal process is to submit a service request
and you should receive a printed estimate after a very short time.
Also this could be perform by a mobile service.

I would recommend looking at the following TMC threads dealing with battery replacement:

12V battery is dead. What do I look for when buying a replacement?

#3​

The OE low voltage battery is covered by the new vehicle 4 year / 50k mile warranty;​

Tesla will replace at no cost if the low voltage battery fails within the warranty period.​

​

If your Tesla Model Y has the older 12V lead-acid battery then you can change it yourself​

(or have Tesla Mobile Service install the replacement).​

​

The price (may be out of date) was $85 (battery only), $135 (with Tesla Mobile Service installation). ​

​

If your Tesla Model Y has the newer 15.5V low voltage lithium battery module​

instead of the 12V lead-acid battery then Tesla Service or Tesla Mobile Service would replace.​

​

#22​

Recap update after leaving Tesla service center: 2019 model 3 FSD. Under 6000 total miles.​

Tesla fee for replacing 12 volt aux battery was $85.00 and a labor cost of under $27.00. ​

Testing the health of 12v battery?

#20​

Maybe your state is different, but the 12V battery in California is about $85 and labor to install $25-50.​

​

And where can you find a 51R battery with a vent hose port for $70?​

​

It's more on the order of $200 (as most of the available ones are AGM).​

Even a conventional vented battery is well over $100,​

so Tesla's OEM battery is by far the cheapest option available. ​

​

You can fault Tesla's parts cost for other items, but their 12V battery really isn't one of them.​

​

 

[EVRider-FL]

They informed me that “it’s a safety issue and that swapping out for a new 12v battery is “not as simple as it seems” blah blah blah.

Had my 12V batteries replaced in both our Model 3 and Model S by mobile service, both under warranty. Took about 10 minutes. I doubt the Y is any more complicated.

 

[ScoobyDoo82]

I would strongly recommend to anyone getting a Bluetooth 12V Battery Monitor to control your battery voltage.
And in particular to check how often the 12V battery get recharged by the DC/DC inverter when your car is sleeping.

Typically the DC/DC inverter will run every two or three days for about two hours. If you notice that the DC/DC imnverter
starts running every day this is an indication that the battery cannot keep the charge and needs to be changed.

For info, when sleeping the battery voltage range is between 13.5 V and 12.5 V.​

​

The DC/DC inverter will be trigger when below 12.5 V.​

When the DC/DC inverter in running the battery voltage is 14.5 V.​

​

When driving the DC/DC inverter is running and is set to about 13.5 V,​

so the 12 V battery doesn't get discharged,​

I guess it was just an over the phone estimate.
The normal process is to submit a service request
and you should receive a printed estimate after a very short time.
Also this could be perform by a mobile service.

I would recommend looking at the following TMC threads dealing with battery replacement:

12V battery is dead. What do I look for when buying a replacement?

#3​

The OE low voltage battery is covered by the new vehicle 4 year / 50k mile warranty;​

Tesla will replace at no cost if the low voltage battery fails within the warranty period.​

​

If your Tesla Model Y has the older 12V lead-acid battery then you can change it yourself​

(or have Tesla Mobile Service install the replacement).​

​

The price (may be out of date) was $85 (battery only), $135 (with Tesla Mobile Service installation). ​

​

If your Tesla Model Y has the newer 15.5V low voltage lithium battery module​

instead of the 12V lead-acid battery then Tesla Service or Tesla Mobile Service would replace.​

​

#22​

Recap update after leaving Tesla service center: 2019 model 3 FSD. Under 6000 total miles.​

Tesla fee for replacing 12 volt aux battery was $85.00 and a labor cost of under $27.00. ​

Testing the health of 12v battery?

#20​

Maybe your state is different, but the 12V battery in California is about $85 and labor to install $25-50.​

​

And where can you find a 51R battery with a vent hose port for $70?​

​

It's more on the order of $200 (as most of the available ones are AGM).​

Even a conventional vented battery is well over $100,​

so Tesla's OEM battery is by far the cheapest option available. ​

​

You can fault Tesla's parts cost for other items, but their 12V battery really isn't one of them.​

​

Very good and helpful advice. Thank you! However, the link you provided for the the BT monitor doesn’t work. Can you please provide me with more info? I definitely want to get one asap. Thanks.

 

[Watts_Up]

Sorry, the first character for the link was missing.

QUICKLYNKS Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car Battery Tester

 

[TMYB-C1]

Sorry, the first character for the link was missing.

QUICKLYNKS Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car Battery Tester

Can you sell me on using this over just looking at the battery health in service mode?

 

[Watts_Up]

Can you sell me on using this over just looking at the battery health in service mode?

I agree that the Service Mode (which became only recently publicly accessible) provides some battery voltage
and degradation estimate, but you cannot access this information directly from your phone without weaking up your car.

Also activating the Service Mode is a little bit cumbersome to do, and not something​

you want to do very often especially when driving and finally forget about and never do it.​

​

As an example, I remember how often I wanted to check my tire pressure but always forget before​

locking my car, and of course the information was gone. So I bought a Digital Pressure Gauge for that reason.​

Well, I know, finally recently, Tesla provided access to the last registered tire pressure value, so may be not too much relevant.​

Also you don't just get a voltage value but a full graph showing:
- How often the DC/DC inverter is activated to charge the battery
- Also you can check if there is any inexpected power consumption while the car is in sleep mode.


1. Picture of typical battery getting charged at 14.5 V every two or three days when the car is in sleep mode.



2. Picture of typical DC/DC inverter set to 13.5 V when the car is in driven so the battery doesn't get discharged.



3. Picture of typical battery getting charged few time a day when the car is in sleep mode because the 12 V battery cannot keep the charge.