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My New Hobby- Resuscitating Discharged and Dead Teslas!

mbp11

Member
Jan 30, 2019
380
207
SF Bay Area
I have recently found that I have a new hobby- showing local Tesla owners how to resuscitate their dead Teslas if they let the main battery (and subsequent 12 volt battery) discharge completely. Have helped several people on the Tesla Forum and even one of my associates who thought he could charge his 2019 Model S up to 100% and then fly to India for 3 weeks (and got stuck there for 6 weeks with the pandemic and cancelled flights. We knew this was going to happen!). Each model Tesla has different challenges. I am surprised more owners have not learned what to do when the Triple A guy


The strategy is the same for each car- have the main Tesla battery charger ready to go, get access to the 12 volt battery or the hot leads in the fuse box, jump the 12 volt battery until there is enough charge to open the charge port, and charge the car!


For the Model X (my car), you need to pull the plastic cover off of the front left side of the car and get access to the two pull cables labeled 1 and 2, release them sequentially, then open the frunk. Pull the housing off the flat part in front of the windshield and just behind the frunk, pop the fuse box in the left side (the battery is deep behind the frunk, you cannot get to it) and locate the hot lead and plug the hot lead of the charger to that and the ground of the charger to chassis, turn on charger and wait. When the car wakes up, open the charge port and charge.


(I also suggested leaving the 12 volt charger attached for a while to get the 12 volt battery up a little, until there is enough main battery charge to continue to charge the 12 volt).


For early Model S’s you don’t need to pop the frunk, but you can get access to the 12 volt battery hot leads by pulling the front nose cone off (carefully)- they are right there behind the nose cone on top. Repeat the charge and charging process.


The late Model S’s are a little more challenging. The emergency frunk releases are behind the right and left front wheel well plastic covers. You have to pry the bottom edge off of both sides and pull both right and left cables to release the two frunk latches. There are a number of good You Tube videos that demonstrate. Once inside the frunk, you have to pull the center plastic cover off (behind the frunk on top) to get access to the fuse box. Pop the fuse box, and attach the hot lead of the 12 volt charger to hot lead, and the ground to the chassis (but you can also barely see the ground of the 12 volt battery partially exposed to the left and I guess you could ground the charger there). Turn on the 12 volt charger, wait, and then when the car wakes up, pop the charge port and charge.


The Model 3 and Ys are unique- there is a round 3 inch port in the front bumper that can be popped open with a plastic pry bar (watch the You Tube videos, you have to pry from the bottom left to avoid damaging the cover) and attached to the cover are two leads, the 12 volt hot lead and a little ways back the ground lead. Plug into the 12 volt charger and wait. You will know what to do with the car wakes up!


So far this has seemed to work for me. I am amused that the hot lead in many of these cars are not covered with a red protective cover to prevent electrical shorting but this is my experience. Would welcome any other user’s experience and advice!
 

DonaldBecker

Member
Aug 24, 2020
138
147
95033
The Model 3 and Ys are unique- there is a round 3 inch port in the front bumper that can be popped open with a plastic pry bar (watch the You Tube videos, you have to pry from the bottom left to avoid damaging the cover) and attached to the cover are two leads, the 12 volt hot lead and a little ways back the ground lead. Plug into the 12 volt charger and wait. You will know what to do with the car wakes up!


So far this has seemed to work for me. I am amused that the hot lead in many of these cars are not covered with a red protective cover to prevent electrical shorting but this is my experience. Would welcome any other user’s experience and advice!

You don't pry on the cover, you push on the 2 o'clock position. The cover pivots to release the lower snap.

The leads are protected by a MOSFET switch acting as an "ideal diode". You can power up the car's 12V circuits, but not draw power from the wires.
 

mbp11

Member
Jan 30, 2019
380
207
SF Bay Area
You don't pry on the cover, you push on the 2 o'clock position. The cover pivots to release the lower snap.

The leads are protected by a MOSFET switch acting as an "ideal diode". You can power up the car's 12V circuits, but not draw power from the wires.

I have no direct knowledge since I don't own a model 3 but according the the you tube video, you can pop the trunk with a 9 volt battery across the circuit if the car is dead and you can change the 12 volt battery from this access to gain access to the charge port.

Just trying to be helpful, but no one will lend me his model three to try it


What do you think?
 

mbp11

Member
Jan 30, 2019
380
207
SF Bay Area
Question is why did his car discharge to zero in only 6 weeks? That's 24 days. Should be ~24% of battery discharge under normal conditions.

Have no idea. This was the description that I received. But the message is never charge your battery to 100% without immediately discharging it o a trip. It is hard on the battery.
 

Kzrman

Member
Jan 26, 2021
15
7
Northeast
Does anybody have a good answer as to how to prep a model Y for being off the road for a extended period of time,
say six months? What would be some of the things to keep in mind?
 

mbp11

Member
Jan 30, 2019
380
207
SF Bay Area
I think the electric cars are a lot easier to store for extended times than ICE cars. Consider suspending the car off of the tires to keep them in round, and keep the car plugged in with a nominal battery charge level of 50-60%. What might be better for battery health is to discharge the car a little during the day and then at midnight have the car charge back up with the scheduled charging feature. Perhaps keep the sentry mode on, and periodically contact the car through the app and have it wake up and tell you how it is doing.

I have a whole house battery (sorry, not a Power Wall) that maintains power to my house as an emergency backup (but is not controllable to go off the grid every evening) since I have occasional power outages where I live in urban California. The battery and system is made by SunVerge and is rated at 7.7 kW but maintains itself at 5.5 kW and cycles a small amount every evening. It discharges down to 85% at night and then charges by solar up to 99% during the day. This is what the company thinks is optimal for battery health.
 

BradYoder

New Member
Feb 21, 2021
4
3
Abbeville, South Carolina
I cant get my tesla charger to come on after my car has sat for quite awhile. THe 12v battery is 100% charged back up but i cannot get the main battery to charge. the light is solid yellow but never starts to charge. What should I do?
 

BradYoder

New Member
Feb 21, 2021
4
3
Abbeville, South Carolina
this is what my screen looks like after 24 hrs of plugged in time
 

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mbp11

Member
Jan 30, 2019
380
207
SF Bay Area
Sorry this is happening. Besides disconnecting the fireman's emergency cable, you can do the following:

I am developing a hobby of resuscitating dead or misbehaving Teslas in my small sphere of influence and there seems to be three levels of severity of reboots. However I am not an engineer, just a user and and an enthusiast. The first level is the double scroll wheel reboot that seems to reboot the MCU and fixes small issues.

A more severe reboot is located under safety and security and forces the car to "turn off." This seems to have fixed persistent misbehavior that the scroll wheel reboot does not. I think this reboots the whole car. I just fixed a MS that would not drive for its owner today. (I hope this fixes the problem, gulp!)

The most deep reboot that seems to clear caches and misbehavior I learned from this forum is to reset the wheel size of the car. I have done this on my MX once or twice and after resetting from 20" to 22" wheels, forces the whole car to reboot and clear memory caches... and then I set the wheel size back to to correct size. That has fixed a few problems I have had.
 

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