These instructions apply to the Tesla Model S (2012-2021).
For other models, please choose your vehicle here.
Disconnecting the 12 V battery on your Tesla Model S (2012–2021) is something owners do for a handful of ordinary reasons — renewing a tired 12 V battery, laying the car up for long-term storage, or making the car electrically safe before any work goes on near the airbags and seat-belt pretensioners. It sounds daunting on an electric car, but the job you are doing here is the low-voltage 12 V battery only. That small battery wakes the computers, runs the door handles and screens, and closes the contactors that connect the big drive battery. The high-voltage traction pack is a completely separate, sealed system, and nothing in this guide asks you to go near it. Done in the right order, the car powers back up and relearns its settings cleanly within a short drive.
Where the 12 V Battery Is
The 12 V battery is at the front of the car, reached by opening the front trunk (the “frunk”) and lifting out the liner and trim to expose the battery below. Once the cover is off you will see two terminals: the negative (−) post, usually the black lead and the one bonded to the body earth, and the positive (+) post, normally the red lead under a protective cap. Identifying the two correctly before you touch a spanner is the single most important step, because the order you take them off and put them back on is what keeps the job safe.
High voltage: never touch, cut, or unplug any of the thick orange high-voltage cabling. That is the traction system and it stays sealed. Everything in this procedure concerns the 12 V battery and nothing else.
Before You Start
- Put the car into its parked, powered-down state and make sure it is not READY — power it off from the touchscreen and give it a couple of minutes so the modules stop talking to each other.
- Keep the key card and any phone key well away from the car so it does not try to wake up while you work.
- Switch off the climate, lights and screens, and close the charge port if a cable is connected — the car should be fully asleep.
- Wait a couple of minutes after powering down so stored energy in the low-voltage modules drains and everything settles.
- Have a set of gloves and eye protection to hand, plus the correct spanner for the terminal clamp, and note down any settings you would rather not re-enter.
Disconnecting
- Power the car off from the touchscreen (Controls → Safety → Power Off) and wait a couple of minutes for it to go fully to sleep.
- Open the frunk and remove the liner and trim so the battery and both terminals are clear.
- Loosen and lift off the negative (−) terminal first, then move it aside so it cannot spring back onto the post.
- Now loosen and remove the positive (+) terminal. If you are working near the airbags or pretensioners, wait a few more minutes before doing so.
Reconnecting
- Fit and tighten the positive (+) terminal first, making sure the clamp is snug on the post.
- Fit and tighten the negative (−) terminal last, again checking it is properly clamped down.
- Refit the frunk liner and trim, then give the car a minute to re-establish its systems before you try to drive.
What You’ll Need to Reset Afterwards
The Model S keeps most of your profile in your Tesla account, so far less is lost than on a conventional car, but a few things settle over the first few minutes and the first short drive:
- Clock and any screen preferences re-sync once the car reconnects.
- Power windows may lose one-touch and anti-pinch — if a window will not auto-close, re-initialise it by holding the switch at the fully closed and fully open limits.
- Air suspension re-levels itself once you are moving.
- TPMS tyre-pressure readings re-store after a short drive.
- Any warning messages that appeared on power-up will usually clear themselves once the car has run for a few minutes.
If a Warning Message Stays On or the Car Feels Off
- Re-check both terminal clamps are tight — a loose negative is the most common cause of odd behaviour.
- Take a short, gentle drive to let the car relearn window travel, tyre pressures and suspension height.
- If a window still will not one-touch, repeat the hold-at-the-limits re-initialisation.
- If messages persist, the 12 V battery itself may be old or genuinely flat rather than anything you did — a weak 12 V is a common fault on these cars.
- A message that will not clear has stored a code — look it up on autodtcs.com.
Frequently Asked Questions
Where is the 12 V battery on a Tesla Model S?
It sits at the front of the car, under the frunk liner and trim. It is completely separate from the high-voltage traction battery, which stays sealed and must never be disturbed.
Which terminal do I disconnect first?
Always the negative (−) first when disconnecting, and reconnect it last. When reconnecting, the positive (+) goes on first and the negative (−) goes on last.
Is it safe for me to disconnect it myself?
Yes — the 12 V battery is low voltage and owner-safe to handle. The rule is simple: stay clear of the orange high-voltage cabling, which is a different, sealed system you never touch.
What will I need to reset afterwards?
Very little, because most settings live in your Tesla account. Expect the clock, window one-touch, air-suspension level and tyre-pressure readings to settle over the first few minutes and a short drive.
Does a new 12 V battery need coding?
A like-for-like 12 V battery of the correct type for your build normally needs no coding. Fit the right specification for the car and let it wake up on its own.
Will disconnecting clear fault codes or reset the service reminder?
It can clear some transient messages, but it is not a reliable way to fix a real fault — a genuine problem will simply log the code again. Read any stored code rather than assuming a disconnect has cured it.
If a warning message stays on after reconnecting, look up the code on autodtcs.com.
Independent guide — not affiliated with Tesla. Always follow your official service manual and safety precautions. Read our full disclaimer.