These instructions apply to the Porsche 718 Boxster / Cayman 982 2016-Present.
For other models, please choose your vehicle here.
Disconnecting the 12 V battery on your Porsche 718 Boxster or Cayman (2016–present) — the 982 — is straightforward once you know one thing that catches owners out: on this mid-engined car the battery is not with the engine. Because the flat-four sits behind the cabin, the battery lives up front, in the luggage compartment. You might disconnect it to fit a new one, to store the car over winter on a maintenance charger, or to isolate the electrics before working near the airbags. In the right order the 718 restarts cleanly and relearns the few settings it drops.
Where the 12 V Battery Is
The 12 V battery is in the front luggage compartment, under the carpet and floor trim. Because the engine is mounted behind the cabin, there is nothing to find in the rear boot — don’t waste time looking there. Lift the front-compartment floor trim to expose the battery and its two terminals: the negative (−) post carries the black earth lead and the positive (+) post carries the red lead, typically under a red plastic cover. Confirm which is which before you start.
Before You Begin
- Switch the ignition fully off and make sure the car is not in its READY state.
- Keep every keyless transmitter well away from the car, outside range, so it cannot wake and re-power the circuits.
- Open the front luggage compartment and remove the floor trim to reach the battery; make sure the doors are shut and the lights, climate and accessories are off.
- Note your radio presets and, if the car uses one, your audio security code.
- Give the modules a couple of minutes to power down before loosening a terminal.
- Have the right spanner ready, and wear gloves and eye protection.
Disconnecting
- Switch the ignition off and keep keyless transmitters well away from the car so it cannot wake up.
- Lift the front-compartment floor trim, then slacken the clamp and disconnect the negative (−) earth cable first; move it clear so it cannot spring back onto the post.
- Now slacken and remove the positive (+) lead.
- If you are working near the airbags or seat-belt pretensioners, insulate the earth cable and wait about a minute before starting that work.
Reconnecting
- Refit the positive (+) lead first and tighten its clamp.
- Refit the negative (−) earth lead last and tighten it.
- Check both clamps are secure — a loose terminal causes flickering electrics and false warnings — then refit the floor trim.
What You’ll Need to Reset Afterwards
After power is restored the 718 relearns a short list:
- Clock and radio presets — re-enter them, plus the audio code if the car asks.
- Power windows — the one-touch and anti-pinch function usually needs re-initialising by holding each switch at its fully up and fully down limits.
- Steering-angle and driver-assistance systems settle over a short drive.
- Seat and mirror memory, where fitted, may need re-storing.
- A new battery should be a like-for-like unit of the correct spec; a straight swap runs fine, but registering it to the car’s energy manager needs Porsche equipment.
If a Warning Light Stays On or the Car Feels Off
- Check both clamps are tight and clean — a poor connection is the usual culprit.
- Let the car relearn over a gentle drive; many lights clear once the assistance systems recalibrate.
- Re-do the window re-initialisation if one-touch or anti-pinch has stopped working.
- If a light stays on, rule out a tired or flat battery and read any stored code — look it up on autodtcs.com.
Frequently Asked Questions
Where is the 12 V battery on a Porsche 718?
In the front luggage compartment, under the carpet and floor trim — not with the mid-mounted engine. Lift the front-compartment floor trim to reach the battery and its terminals.
Is the Boxster different from the Cayman?
No. The 718 Boxster and Cayman share the same platform and layout, so the battery location and this whole procedure are identical for both bodystyles.
Which terminal do I disconnect first?
Always the negative (−) earth first, and reconnect it last. On reconnection the positive (+) goes back on first, then the negative — this keeps the risk of a short to the body to a minimum.
What needs resetting after disconnecting?
Re-enter the clock and radio presets, re-initialise the one-touch windows, and let the steering-angle and assistance systems relearn on a short drive. Seat and mirror memory may also need re-storing where fitted.
Do I need to code a new battery?
A like-for-like swap will start and run the 718 normally. Registering the new battery to the energy manager needs Porsche diagnostic equipment — worth doing at a service so charging is managed correctly, but not essential to get moving.
Can I jump-start it instead of disconnecting?
If you only want to recover a flat battery, a careful jump-start avoids the disconnect. Disconnecting is for renewing the battery, winter storage on a charger, or isolating the electrics for work near the airbags.
If a warning light stays on after reconnecting, read the stored code and look it up on autodtcs.com.
Independent guide — not affiliated with Porsche. Always follow your official service manual and safety precautions. Read our full disclaimer.