2015-2019 Smart Fortwo — Replace Battery

1

Prepare the vehicle

Park on level ground, set the parking brake, and open the hood (or access panel). Note radio presets and any power-window/sunroof settings that may reset. On EVs/hybrids the 12V battery may be in the cargo area, under a rear seat, or under a cover — not always under the hood. Wear gloves and eye protection.

2

Disconnect negative first

Loosen the negative (−) terminal clamp and remove it first, then disconnect the positive (+). Keep the negative cable clear of the terminal so it cannot spring back into contact.

3

Remove the hold-down

Remove the battery hold-down clamp, J-bolt, or tray fastener. Note the group size stamped on the old battery and the terminal orientation before lifting.

4

Lift out the old battery

Lift the battery straight up and out. Batteries are heavy — use a battery lifting strap if available. Keep it upright to avoid acid spills.

5

Clean the tray and terminals

Clean corrosion from the tray and cable ends with a wire brush and battery terminal cleaner. Dry the tray and check the tray drain is clear.

6

Install the new battery

Set the new battery in the tray matching group size and terminal orientation. Install and tighten the hold-down snugly — do not crush the case.

7

Reconnect positive first

Connect the positive (+) cable first, then the negative (−). Ensure clamps are tight and protected with covers. Do not overtighten soft lead posts.

8

Reset and verify

Start the vehicle and confirm charging/12V system status is normal. Reset the clock/radio. Some vehicles need a window/sunroof or battery registration reset after replacement.