Dead 12V Battery with a bunch of codes.

[CKwik240]

2018 M3P. 63k miles.

Yesterday morning, I got out of the house, opened the trunk and placed some items in and then went to leave, only the front door wouldn't open. Could not access through the app. Tried the key card. After a few attempts, it popped open, but the window didn't lower itself. Got in and the charge cable was still attached so I got back out to release it and it wouldn't respond. Tried to disconnect from the car and the screen went black. Realized the battery might be dead. Could not open the frunk. No 9 volt or 12 volt source available. Went and got a 9 volt battery and no response. Couldn't do anything so Ubered to my mom's to borrow her Model Y since my parents are out of town for the holidays then went to my business for the day. Noticed the Tesla app came online at some point and while I had it up, I tried popping the Frunk. When I got out, picked up an A23 battery just in case. Got home and Frunk had not opened. Used the battery trick and popped it open. I had my NOCO charger in there so I plugged it in. The lowest red bar started blinking slowly. So battery is dead for sure. Noticed a crap ton of codes on the screen now.

Had to manually release the charger so I could plug my mom's car in since I had kept it at 50% while they were gone. Left the 12v battery charging overnight and when I got up, the lowest bar is still red. So dead battery for sure. Pulled the ground but left the charger in supply mode. No change. I think the dc-dc converter is active and keeping power on. HV battery is losing range slowly and computer is responsive. One of the codes indicated it's unable to support switching off features to conserve energy. Though the frunk still does not open with the controls and left side doors do not open. 2 button reset doesn't work. I'm about to go pick up a NOCO jump starter.

I set up a service appointment yesterday for tomorrow morning. The estimate includes the battery replacement as well as a low voltage circuit integrity check at $275.

I'm trying to see if I can get it to respond normally with the 12v supply voltage with the hope that I will only need the battery replaced. I can't even plug the wall charger in as there is no response. A lot of functions are disabled. Anyone know how to reset everything? Here's some of the codes:

This is great start to a new year. On a side note, my security camera monitor at my business went out yesterday so gotta but a new one today as well. It's an old monitor so it's not surprising, but totally bad timing.

 

[android04]

Keep in mind that the two wires behind the tow hook cover are only to jump open the front trunk, which it seems you did. Just want to point out that they do not connect directly to the 12v battery. Did you close the frunk again after connecting the charger? You mention that it doesn't open again?

Here's what I would do to reset the car if
it is inside a garage. Lower all the windows and keep the driver and passenger rear doors open. Disconnect any battery charger or jump starter you have on the 12v, and disconnect the 12v battery ground cable. Then use the two latches under the front edge of the rear seat cushion to lift it up. Unplug the black and gray connector on the passenger rear side under the seat to disable the high voltage battery from powering up the low voltage system. You should hear a clunk and everything should power down. After a minute, you can plug the connector back in under the seat cushion, then connect the 12v battery. You might have to jump starter the 12v battery at this point to get the car to start again.

 

[E90alex]

Don’t worry about any of that until the battery is replaced. Tesla will probably clear the errors after replacing the battery.

 

[CKwik240]

Keep in mind that the two wires behind the tow hook cover are only to jump open the front trunk, which it seems you did. Just want to point out that they do not connect directly to the 12v battery. Did you close the frunk again after connecting the charger? You mention that it doesn't open again?

I can still open it with the battery on the two wires. It just doesn't open with the controls.

Here's what I would do to reset the car if
it is inside a garage. Lower all the windows and keep the driver and passenger rear doors open. Disconnect any battery charger or jump starter you have on the 12v, and disconnect the 12v battery ground cable. Then use the two latches under the front edge of the rear seat cushion to lift it up. Unplug the black and gray connector on the passenger rear side under the seat to disable the high voltage battery from powering up the low voltage system. You should hear a clunk and everything should power down. After a minute, you can plug the connector back in under the seat cushion, then connect the 12v battery. You might have to jump starter the 12v battery at this point to get the car to start again.

I'll take a look at that. Thanks.

 

[CKwik240]

Don’t worry about any of that until the battery is replaced. Tesla will probably clear the errors after replacing the battery.

I'm just trying to see if it clears whatever concerns Tesla has that has them putting the $275 diagnostic procedure in the estimate. Maybe even ease my mind a bit.

I actually had the service day wrong as well. It's on Wednesday.

 

[davewill]

If you don't want to pay the diagnostic charge, you could just request they change the LV battery. Or you could simply buy the LV battery and change it yourself. Of course, if it doesn't fix everything, you will then have to pay the diagnostic fee.

 

[CKwik240]

If you don't want to pay the diagnostic charge, you could just request they change the LV battery. Or you could simply buy the LV battery and change it yourself. Of course, if it doesn't fix everything, you will then have to pay the diagnostic fee.

I had set up the appointment as I'm the only one watching the family business while my parents are visiting my sis and I didn't think I would have time to make it down to the service center. I managed to find a bit of time this morning before opening to pick up the battery. Installed it tonight, reset everything and it's working fine. I went ahead and cancelled the appointment.

I also tried resetting it by disconnecting the connector under the rear seat. It didn't fix it, but it got the charge door and left side doors working. I reckon the frunk might have been working after that, but I didn't try it.

It's rather disappointing there aren't any non-OE options available at local stores. I'd go lithium, but reading through the threads, it sounds like a big hassle everytime Tesla changes something that causes some kind of issue. I've ordered a set of charger leads (NOCO) that I can connect at the terminals. I want to evaluate if it can find a spot where I could hide the end but have easy access. I used to occasionally plug my motorcycle to a battery tender this way. While I'm not sure there would be any benefit to maintain the LV battery this way, but it would allow me to get some power to it in case it goes completely dead. When this first started, I'm not sure the emergency frunk release would have worked as the car wouldn't unlock. It just came back online sometime during the day while I was at work. Perhaps as the temps increased, it got just enough juice to kick things on and then just relied on the HV battery to keep things minimally running from there.

At this point though. I'm just glad it's all back to normal at a pretty minimal cost.

 

[Jkimo11]

I've been reading a few "I went out to my car and it was dead" kind of stories..... what percentage of Tesla owners experience this I wonder. I live hours from a service center.

 

[joebruin77]

I'm sorry you had to deal with this.

I see you have a 2018 M3P like me. Just curious, have you previously replaced the 12v battery or is this the original 12v battery? If you have previously replaced it, how long ago was that?

 

[CKwik240]

I'm sorry you had to deal with this.

I see you have a 2018 M3P like me. Just curious, have you previously replaced the 12v battery or is this the original 12v battery? If you have previously replaced it, how long ago was that?

I bought my M3P used so I hadn't replaced it prior. I just checked and the battery was manufactured 11/7/2018, so it appears it's the original.

 

[joebruin77]

I bought my M3P used so I hadn't replaced it prior. I just checked and the battery was manufactured 11/7/2018, so it appears it's the original.

Thanks for letting me know.

Not sure if you have already seen it or if you would find it informative, but here is an interesting post I started quite a while ago discussing whether or not it is a good idea to proactively replace the 12v battery. Personally, I think it is "cheap insurance" to replace the 12v battery once every 2 years:

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

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...

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