All batteries dead, can’t unlock car.

[Kcct82]

Thanks for all the helpful replies!

So I’ll be attempting to open the charge port with the ICE battery (with Tesla’s negative disconnected). Say I get the charge port open and electronics fired up. Should I go ahead and plug the main charger in with the ICE battery still attached? Or should I connect Tesla’s 12v back before charging? Thanks!

 

[Kcct82]

My concern with the second route (putting Tesla’s potentially dead 12v back on) is that the charge port won’t recognize the charger without functioning electronics since the 12v is depleted or dead.

 

[brkaus]

Thanks for all the helpful replies!

So I’ll be attempting to open the charge port with the ICE battery (with Tesla’s negative disconnected). Say I get the charge port open and electronics fired up. Should I go ahead and plug the main charger in with the ICE battery still attached? Or should I connect Tesla’s 12v back before charging? Thanks!

I would leave the ICE battery attached.

First step, once electronics are fired up, is to check the battery level of the main pack. Not much you can do about it, but it would be good news if it is in the middle range. Also, set the charge level to 80 or so. No need to top it off if it happened to be set very high.

You can try to trickle charge the 12v once it's disconnected, but I think you will have to just buy a new one.

 

[Sophias_dad]

Is there some reason you don't just call a ranger out to replace your 12V under warranty?

Aside from that, I'd trickle charge the old 12V while its disconnected and try to charge(or at least check on) the main battery while the ICE battery is connected.

 

[brkaus]

Is there some reason you don't just call a ranger out to replace your 12V under warranty?

Aside from that, I'd trickle charge the old 12V while its disconnected and try to charge(or at least check on) the main battery while the ICE battery is connected.

Would “I have a model 3 parked for a very long time without being plugged in” fall under warranty?

but, I do agree. Buy the 12v from Tesla or have a ranger come out and put it in.

 

[rrolsbe]

My concern with the second route (putting Tesla’s potentially dead 12v back on) is that the charge port won’t recognize the charger without functioning electronics since the 12v is depleted or dead.

Since you let the 12V battery totally discharged and if Tesla can see that it did, the battery might not be covered under the 4 year/50K mile warranty period. A 12V battery is only required for about 10 seconds to close the contactors and allow time for the 12V DC-to-DC converter to start operating (car to wake up) . After the initial wake up, the car is fully operational without the need of a 12V battery attached, assuming the DC-to-DC converter is applying a voltage to the battery cables and to the rest the the cars 12V loads. I would disconnect the 12V battery that you call an ICE battery after the initial startup and attach a Smart AGM battery charger to the dead M3 battery. The car should remain awake if you are charging the traction battery, driving the car, have summons enabled or anything that requires 12V. The charger would be connected across the battery posts with the negative cable NOT attached. After allowing time for the AGM battery time to be charged, I would remove the charger and verify the post voltage was at least 12.6 volts. If the fully charged unloaded post voltage is below 12.6V maybe even up to 13V. the battery probably needs to be replaced or it could even have one or more shorted internal cells. I am not sure what the car would do if the battery had one or more shorted cells and you reconnected the negative cable to the battery post?

 

[Sklith]

I had the 12V battery in my Model 3 die a couple months ago.
One morning, I tried to open my doors, used the keycard as well, no good. I had to go to work so I took my motorcycle instead. I came home later that day, and used a lithium jump starter kit on the front bumper, then jump started it for real under the hood. My car was drivable but the A/C didn't work. I had Mobile Service come and replace the battery, was super quick.

I had no prior warning that the 12V battery was dying.

 

[rrolsbe]

I had the 12V battery in my Model 3 die a couple months ago.
One morning, I tried to open my doors, used the keycard as well, no good. I had to go to work so I took my motorcycle instead. I came home later that day, and used a lithium jump starter kit on the front bumper, then jump started it for real under the hood. My car was drivable but the A/C didn't work. I had Mobile Service come and replace the battery, was super quick.

I had no prior warning that the 12V battery was dying.

Never tried the AC with the 12V battery disconnected. The car was drive-able and everything seemed to work except for a 12V on screen battery error which would be expected.

 

[pjensen]

I am not sure what the car would do if the battery had one or more shorted cells and you reconnected the negative cable to the battery post?

My guess is the inverter would see a high load (too much current) and shutdown itself to protect its components.

 

[jstjohnz]

I would leave the ICE battery attached.

First step, once electronics are fired up, is to check the battery level of the main pack. Not much you can do about it, but it would be good news if it is in the middle range. Also, set the charge level to 80 or so. No need to top it off if it happened to be set very high.

You can try to trickle charge the 12v once it's disconnected, but I think you will have to just buy a new one.

The problem is that the main battery pack is fully discharged also, that's why his 12v battery is dead. The vehicle was left unused and not on charger for 'several months'. If that was my vehicle I would be in one hell of a hurry to get it going to the point of being able to recharge and ascertain the health of the main battery. I don't think the OP shares that sense of urgency. This thread is more than a week old and it seems like the only thing done so far is to get the frunk open.

 

[brkaus]

The problem is that the main battery pack is fully discharged also, that's why his 12v battery is dead. The vehicle was left unused and not on charger for 'several months'. If that was my vehicle I would be in one hell of a hurry to get it going to the point of being able to recharge and ascertain the health of the main battery. I don't think the OP shares that sense of urgency. This thread is more than a week old and it seems like the only thing done so far is to get the frunk open.

At some point, the car will disconnect the main pack and let the 12v just die. The roadsters did not to this, but the current Tesla models try to protect the main pack.

 

[jstjohnz]

I have seen stories about permanent pack damage, but you are correct those were all roadsters.

 

[Phlier]

At some point, the car will disconnect the main pack and let the 12v just die. The roadsters did not to this, but the current Tesla models try to protect the main pack.

Yup.

From what I've read, the main battery pack isn't truly at zero when it says it's at zero; there is a portion of the pack that isn't seen or usable to the driver. The BMS will disconnect the main pack from the car when only the only energy remaining in the pack is the hidden buffer. This is to prevent people from completely discharging their packs and causing damage to it.

But even with zero load on it, these types of batteries will self-discharge over time. So you can't simply say, "oh, well the BMS took the system off line to prevent battery pack damage, so it's going to be fine," as the BMS can't do anything about the self-discharge. Eventually, a pack that says "zero" will self discharge through the remaining buffer energy, and the pack will completely discharge, causing damage.

Hopefully, the OP will be able to get his car charged back up before this happens.

 

[Willh24]

I had this problem, my 12v was bad so what I had to do was connect a battery charger to the 12v while connected to the car and then opened up the charge port and plugged it in and the car started charging the main battery pack after about an hour. After the car was up to 50%, I disconnected the 12v charger to see if the main would keep it charged. Seemed like it was, but I didn’t trust that battery anymore so set up and appointment and had Tesla replace it. When I asked if I could buy the 12v and replace it myself, they said no because they wanted to make sure the 12v battery was bad and nothing else in the system was going on.

 

[toolman335]

The problem is that the main battery pack is fully discharged also, that's why his 12v battery is dead. The vehicle was left unused and not on charger for 'several months'. If that was my vehicle I would be in one hell of a hurry to get it going to the point of being able to recharge and ascertain the health of the main battery. I don't think the OP shares that sense of urgency. This thread is more than a week old and it seems like the only thing done so far is to get the frunk open.

This is a fantastic point^^^^^
I've seen divorces happen quicker than the OP getting juice to his car. The well-being of the car is on life support now. Long-term damage must have been inflicted.

 

[Kcct82]

Thanks for the replies. To answer some of the questions from earlier...

I did call Tesla first. I explained to them what happened just like I did here in the first few posts. Their solution was to change my 12v for $285. I told them “Let’s get it to open first (utilizing the tow hook spot) so we can charge the main battery ASAP. If the 12v is dead, I’d be happy to pay $285.” The next thing they told me is I’d have to tow the car to them to get it open instead of sending someone out to give it a little zap to open the frunk. I decided to stop listening to Tesla after that.

Next, I called AAA to send someone out to give it a little zap. They said they don’t do Tesla’s.

So finally, here I am on this forum. Getting a ton more help from you guys than the previous two “solutions“.

Also, I know it’s an expensive car to have sit around. The problem is we got the car a couple of months before COVID hit us. Since then, our family didn’t need a second car, so the 3 has been sitting there. We have a Model X for when we go out to get groceries. Trust me, I hate to have this car just sitting there wasting away.

Now for the update, I disconnected the negative on the 12v and connected the car to an ICE battery. Everything powered right up. I’m now charging the main battery at home from a regular wall socket. The 12v from the ICE car was accidentally disconnected shortly after I started charging the car. Nothing happened and the 3 is continuing to charge. The main screen is still on and it just says “12v battery disconnected”.

Assuming I revive the main battery after a few hours of charging. What do I do next? Connect the old 12v back on and see if the main will charge it? If so, do I simply connect the negative back on? Or is there a special procedure to installing 12v batteries? Thanks again for all your help.

 

[Sophias_dad]

No special procedure I know of for installing 12V batteries, but it probably wouldn't hurt to open the frunk and tell the car to 'power off' before you do.

If you end up needing a new battery, I'd consider the Ohmmu lithium or Optima AGM battery(I understand group 51R fits nicely), if your're gonna get charged $285 anyway. I'd heard that the OEM battery is only like $90 if you get it from the shelf at a Tesla dealer, so maybe the extra ~$200 is to install it. I think the Optima is around $230, which is admittedly pricey and overkill. The Ohmmu is double that, but is lighter and might last considerably longer.

 

[1FASTROD]

Once a 12v battery goes completely dead it will not work well even if it charges back up (I.e. damaged plates). I suggest you replace the 12v battery even if the rest of the car appears okay. It'll save you grief in the near future.

 

[miimura]

There is no problem reconnecting the 12V battery at this point. However, as previously stated, its life has been drastically shortened by draining it so completely. If you want to postpone the expense as long as possible, you could just keep the old battery in the car until the "12V Battery Needs Service" message comes up. That is, assuming it properly charges the first time.

 

[Kcct82]

Ok thanks guys.

The main battery has been plugged in for a few hours now. It was showing “0 mile” for the first couple of hours, and then “0 mile” with a little bit red on the battery image. Now it’s at “5 miles”. I’ll continue to charge it to at least half full before installing the 12v.