Mercedes-Benz SL key fob battery
6 of the 31 model years listed for the Mercedes-Benz SL have a proven battery. The most common answer is 2 x CR2025. Rows below run oldest to newest; a year can appear twice when the car came with more than one kind of key.
- 1996-2004Unknown
Not confirmed yet
- 2005Smart key
2 x CR2025
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “Lithium, type CR 2025 ... always replace both batteries.”
Find CR2025 on Amazon - 2006-2008Unknown
Not confirmed yet
- 2009Smart key
2 x CR2025
Owner's manual: manualslib.com (checked Nov 2, 2026)
Manual text: “always replace both batteries ... Lithium, type CR 2025”
Find CR2025 on Amazon - 2010Unknown
Not confirmed yet
- 2011Smart key
2 x CR2025
Owner's manual: manualslib.com (checked Nov 2, 2026)
Manual text: “always replace both batteries ... Lithium, type CR 2025”
Find CR2025 on Amazon - 2012Unknown
Not confirmed yet
- 2013Smart key
CR2025
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2014-2021Unknown
Not confirmed yet
- 2022-2024Smart key
Not confirmed yet
- 2025Smart key
CR2032
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2032 3 V cell battery.”
Find CR2032 on Amazon - 2026Smart key
CR2032
Owner's manual: manua.ls (checked Nov 1, 2026)
Manual text: “You need a CR2032 lithium cell battery (3 V).”
Find CR2032 on Amazon
Changing the battery
Smart key (push-button start)
- Start by freeing the hidden metal key: there is a latch or slide on the case, and the blade comes out once it moves.
- Look inside the empty key slot for a notch. Put the tip of the metal key or a small flat screwdriver wrapped in tape there and twist gently until the shell splits.
- Note which side of the old coin cell faces up (usually the side with the writing), lift it out with a plastic tool, and press the new one in the same way.
- Reassemble, refit the emergency key, and check that the car sees the fob when you press start.
On the common chrome Mercedes key, a slide at the back frees the mechanical key, and pushing that key into the opening releases the battery tray.
This key takes two CR2025 cells. Change both at the same time and stack them the way the old pair sat; mixing a fresh cell with a tired one shortens the life of the new one.
A CR2025 is 20 mm across and 2.5 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.
A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.
Keep spare coin cells away from small children. A swallowed coin cell can burn the throat within hours; if it happens, go to an emergency room at once.