How to Replace the Battery in an Older Mercedes-Benz SL550 Key?
3 Answers
Method for replacing the battery in an older Mercedes-Benz SL550 key: 1. Flip open the tab at the rear end of the key to remove the mechanical key; 2. Insert the mechanical key into the side slot of the key, press the internal gray button, and with the other hand, push the rear end of the key upwards; 3. Once a gap is created, the mechanical key can be removed; 4. Take out the rear end by hand to replace the battery. In terms of power, the Mercedes-Benz SL550 is equipped with a 4.7-liter V8 twin-turbocharged engine, delivering a maximum output of 435 horsepower. Regarding body dimensions, the Mercedes-Benz SL550 measures 4633mm in length, 1877mm in width, and 1300mm in height, with a wheelbase of 2585mm.
I once helped a friend replace the battery in their SL550 key. This older Mercedes model typically uses a plastic-shell folding key, which isn't too difficult to disassemble. You'll need a small flathead screwdriver or even a coin to gently pry open the seam in the middle of the key - just don't use too much force to avoid scratching the casing. After removing the old battery, check the model number (CR2032 is very common and available at supermarkets or auto parts stores). When installing the new battery, make sure the positive side faces upward, press it firmly in place, then snap the cover back on. Test the key by pressing a button to see if the light comes on. If you're not comfortable doing it yourself, there are plenty of video tutorials online. Clear your workspace before starting to prevent losing small components. Replace the battery when the key starts responding poorly - don't wait until you're stranded trying to open your car. I recommend keeping spare batteries at home and replacing them every 2-3 years. Older vehicles require more diligent maintenance. After each replacement, inspect the overall condition of the key to prevent moisture damage or impact-related signal issues. Taking care of these small details makes car ownership much smoother.
Here's how I handled our old SL550 when the key fob battery died: First, identify the key model—usually the folding type with the Mercedes logo. Find a quiet spot to work slowly. Use a small knife or nail clipper tip to gently pry open the key along the seam, taking care not to cut yourself. Remove the old battery, noting its orientation, and replace it with a new CR2032 (wrong direction = no light). Press the casing firmly after replacement and test remote unlocking. Be cautious not to lose internal springs or chips—vintage parts are precious. Daylight is best for visibility; use a box to organize small components. Key batteries drain every 2-3 years—keep a spare handy (inexpensive). Avoid water exposure. If issues persist post-replacement, visit the dealership. Regular maintenance extends key life. Bottom line: Patience and precision win the day—take it step by step.
