Tutorial on Replacing the Battery in an Older Mercedes SL400 Key

[Lincoln]

Method for replacing the battery in an older Mercedes key: 1. Before replacement, it is best to first understand the battery model of the car key, then select a new key battery according to the specified model. 2. Push the marked switch upward from the tail of the key, and the hidden mechanical key will pop out slightly, allowing you to remove the mechanical key. 3. Still at the tail of the key, use the just-removed mechanical key to press against the marked position, and with a slight force, the key shell can be opened. 4. After opening the key shell, you can see that the battery position is relatively deep. Insert an object along the gaps on both sides, gently pry, and the old battery can be removed. 5. Install the new battery, ensuring the positive and negative poles are not reversed. Then follow the installation steps: insert the top of the shell first, then press firmly on the other end to complete the battery replacement. Finally, don't forget to reinsert the mechanical key.

[AylaLynn]

I've figured out how to replace the battery in an older Mercedes SL400 key. There's usually a small gap at the back of the key. Use a thin tool like a plastic card to gently pry it open—avoid metal to prevent scratching the casing. The battery model is CR2025, which you can buy for just a few dollars at the supermarket. When opening it, pay attention to the orientation of the old battery, and insert the new one in the same direction, with the positive side aligned to the marking on the circuit board. After reassembling, test the remote locking function from a distance. If you encounter any difficulty, don't force it to avoid breaking the clips—it's better to watch an online tutorial for guidance. The battery typically lasts one to two years; opting for branded ones can extend its lifespan. Avoid exposing the key to high temperatures in daily use to prolong battery life. Doing it yourself is both convenient and cost-effective—just prioritize safety.

[SanDakota]

Having driven a Mercedes for years, replacing the SL400 key battery is a breeze for me. Start by locating the small gap along the edge of the key, then gently pry open the back cover using a fingernail or credit card—be careful not to apply too much force and damage the plastic casing. Remove the old battery and note its model, such as the common CR2025, which is easy to find. When inserting the new battery, ensure the metal side faces inward and aligns with the circuit markings to avoid reversing it and affecting functionality. After closing the cover, test all buttons like unlock and lock to confirm responsive operation. Keep in mind that prolonged use can deplete the battery, weakening signal reception, so it's advisable to check the battery status annually. If unsure, purchasing a new battery online with an installation toolkit can simplify the process.

[LaCaleb]

The key to replacing the key battery lies in the prying technique. For the older SL400 key, there's a tiny gap where you can carefully lift the back cover using a small screwdriver. The battery is a standard CR2025 size—make sure to observe the correct polarity when replacing it to avoid reverse installation. After completion, test the remote response distance. Be careful not to wet the internal circuitry, as it may affect functionality.