Battery Service Intervals
Mercedes-Benz black cased batteries are Valve Regulated Lead Acid (VRLA) and have no maintenance. White cased lead acid batteries should be serviced regularly. The electrolyte should be topped off with distilled water at every service. Only use distilled water in a battery. Make sure the terminals are clean, and wipe it down. Use baking soda solution if you have acid on it otherwise plain water is fine. Although these routinely receive no maintenance even during services, they have a surprising ability not to dry out and still last 5 years ignored. We don't recommend overlooking battery maintenance, and the electrolyte level should be checked with any service and the battery tested. Midtronics battery testers are now routinely able to identify a battery that needs replacement without doing a load test, by using inductive tests to check conductivity and calculate theoretical output. Dealers only use this tool for warranty replacement, because it is quicker and more accurate.
Mercedes Benz batteries are expensive but they are very heavy duty. Hold an aftermarket replacement in one hand and the factory in the other you can feel the weight difference. The plates on the OE battery are thicker and have more surface area. They hold up better longer subject to shock and thermal cycling and don’t dry out easily. If you have to buy an aftermarket battery buy an exact fit as they can be unsafe if not secured in a collision. Interstate supplies Mercedes batteries so they are an excellent OEM source. We can order either for you.
Another overlooked point is the battery vent tube. The vent tube discharges any battery vapors or gas out of the vehicle. Without the vent tube gases collect in the vehicle or flow over delicate components such as the vehicle wiring harness. Don’t forget to connect the vent tube if present, as there are two outlets on each end. One is plugged, so don’t forget to take the plug from the old one. The other attaches to the vent tube. If you replace the battery you may want to use a vehicle memory keeper or you may have to normalize the windows, roof, steering angle sensor, code the radio, and set as many as two clocks on some models.