The most important part of your Tesla is the battery. Range anxiety is real, but what happens if the battery dies? Don’t be alarmed. We’ll have you back with power shortly.
All Teslas have two batteries, 12V and High Voltage. The 12V dies because it has been drained flat or is at end of life. The High Voltage dies because it has reached 0% because of lack of charge.
In this article, we’ll look at both batteries and what to do when they die, and how to fix them.
Tesla 12V Battery Dead
Most people are surprised to hear that all Tesla have a regular 12V acid battery.
The 12V runs all the items we don’t really think about. We just expect them to work, such as locking and unlocking windows and media units.
When the 12V dies, this is a real problem as you can’t even get into your car. Because it’s a 12V we can boost it like an ICE (Internal Combustion Engine) car, but first, we have to gain access to it. It’s located in the frunk. If you can’t open your frunk Tesla has incorporated a way for you to do this.
Opening the Frunk
- Locate the tow cover (on your front bumper)
- Press the top of the circle to release
- Gently pull the cover towards you
- Two wires with connectors should be visible
- One red and one black
- One is usually attached to the two cover
- Attach each to a booster pack (Red to Red and Black to Black)
- Or a small 9V battery will also work
- The frunk latch will release
Once the frunk is open, locate the 12V. You’ll need to remove two attached covers with small plastic clips. Gently pull upwards; you don’t want to break the clips as you need to put these covers back on.
Under the second cover, you’ll see the 12V. A booster pack is a preferable way to charge your 12V.
Connect the red to red (the tesla end may have a jump post that requires you to remove the cap – it depends on the Tesla Model you have). Connect the Black to black from the booster to any metal part of the mount.
Switch on your booster, and your charge will start. The car may not come to life immediately; it can take 10-15 minutes.
You can jump your Tesla from another ICE car but not from another Tesla or EV. This can cause irreparable damage to your Tesla computer and the donor car.
Reasons Your 12V is Flat or Dead
Now that you’re back up and running, you will need to check why your 12V was flat or dead. There are a couple of common reasons:
- Something was left turned on
- Battery at the end of life
- Model S and Model X have 12V issues
Something left turned on
This is the most common reason you have a flat 12V, no matter what type of car you have.
Either interior lights have been on overnight, or a media unit has been left on for a prolonged period. You may have been washing or vacuuming your car and listening to some tunes, which has drained the battery.
Or you possibly went out to get something from your car late at night, you turned on the interior lights and forgot to turn them off again. It happens, and it’s not a big deal. A quick boost, and everything is working again. It’s more the inconvenience of it.
12V Battery at the end of Life
A standard 12V battery lasts approximately 4-5 years. If you’ve had your Tesla for that long or you are unsure if the battery has ever been replaced, if you have bought a used Tesla then it might be time for an upgrade.
They are widely available and easily switched out, but you might not feel comfortable doing this yourself. If not, you can easily book an appointment with a Tesla Service Center. This can be done through your Tesla app.
- Open Tesla App
- Select Service
- Select the problem you have
- Insert any details you think are relevant
- Enter the address you are available at
- Enter a time and date that suits
- Enter a cell number where you can be easily contacted
If you have boosted your battery a couple of times recently, and it doesn’t seem to be holding a charge, then the most obvious reason is that your 12V needs to be replaced.
Model S and Model X have 12V Issues
In late 2021 Tesla announced that all new Model S and Model X would be installed with Li-Ion 12V batteries. There had been reports of these model’s batteries failing in a much shorter time frame than normal when using the 12V acid battery.
The new Li-Ion replacement is much lighter (1.8kg) and much higher capacity (16V), which means it’s much more ergonomic for the car and also should never lose full charge.
If you’re having battery issues (failing repeatedly) and you have a Model S or Model X, then you might need to make an appointment with the Tesla Service Center to install the new Li-Ion battery.
High Voltage Battery Dead
Your High Voltage battery being dead can be a little more problematic as we can’t just take a booster to it. It also depends on where you are, at home or on the highway. We’ll look at each next.
If you have been on vacation or your Tesla has been out of use for some time, it is more than likely completely flat. But being at home is not such a problem. We simply need to plug it in and wait for the charge to build. Granted, this may take some time, depending on which Level charger you have, but it’s not the end of the world.
Even without any use, your battery will deplete at 1-2% per day and more if you check it on your app while on vacation.
Every time you check your Tesla, it wakes up for about 15 minutes, which leads to quicker battery depletion.
On the Highway
When you are out driving, you must keep an eye on the range of your battery. Your onboard computers constantly check how much range you have left and compare this to the distance away from a charger. When your battery gets to 10%, the notifications will become much more apparent, and you should not ignore them.
There is a 10-15 mile buffer in every battery, but this is not the case if you are highway driving and if the temperature outside is very low.
If you are not going to make it to the next charger, you need to pull off the highway and park in a safe place, and call Roadside Assist. It’s much less of a challenge to transport your car with even a 2-3% charge than with 0%.
Converting to Transport Mode
When you call roadside assistance, they will send someone who will either have a power pack to give you some charge or, more likely; they will put your car on a transporter and bring you to the nearest charger.
Some tow companies now specialize in rescuing EVs, and some will be able to give you a charge boost but to be honest, it’s nearly quicker to get them to bring you to a charge point as they are not going to have a fast charger onboard. Unlike a gas car, no one can bring you a can of electricity.
The more likely outcome will be that they tow you to the nearest charger or your home – whichever is nearer within 50 miles.
To call Roadside Assist, your car must still be in warranty or extended warranty (4 years or 50000 miles). Although you can avail of Roadside Assist, an Out of Charge call is not a Free service and will incur a cost.
To log a call:
- Open Tesla App
- Select Roadside Assist
- Select Out of Charge
- Request some help
They aim to be with you within the hour but realistically, by the time they arrive and get you transported to wherever you choose, your day will be a write-off.
Towing your Tesla
Your Tesla can only be moved ‘flat’ in a specific way. It must be transported on a flatbed truck. The front and/or back wheels can’t be moving while being towed.
The regenerative braking system uses the energy from the brakes and wheels by transferring it to the Li-Ion High Voltage battery. If the wheels are moving, but there is no power, this will cause damage to the drivetrain.
When the tow truck arrives, you must ensure that your Tesla is moved correctly onto the truck. To do this, your Tesla needs to be in Transport Mode.
- Put your car in park
- Press and hold on to the brake
- Select Controls – Service – Towing
- Hold until Transport turns ‘Blue’
It is now safe to transfer your Tesla to the flatbed tow truck. Unfortunately, if your car is now at 0%, you no longer have the ability to do this, and this is a much bigger problem.
If your Tesla is completely flat, you must inform the tow company. They will have to transfer your car to the flatbed using ‘Dollies.’ These extra wheels placed under your Tesla wheels to allow it to move without your Tesla wheels actually turning.
Your Tesla can’t be pushed or pulled onto a flatbed unless it has dollies attached.
This is an extra towing expense on top of the already 0% battery charge.
We all have busy lives, and sometimes we get into low-range situations that ultimately lead to Roadside Assist.
However, your onboard computer is always on the lookout for you. It definitely is not something you should ignore or think that you know better. If it says you should leave the highway, then please do.
Tesla recommends that your battery works best at 20-80% charge. Allowing full depletion regularly leads to battery cells dying. Although your High Voltage battery is covered under warranty Tesla Service Center will know from your onboard computer why the cells are dead.
The High Voltage battery is not known to die for no reason. If they are not charged regularly, they will degrade to the point that they can no longer receive a full charge.
Sitting on the side of the highway is no fun. You can’t even call a friend to bring you some ‘electricity.’ It’s better to be always topped up, but sometimes we find ourselves short, and Tesla Roadside Assist is there to help us out.
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