Got a 2008 Mercedes CL500, one of the batteries is getting drained when the cars running

SOURCE: 1993 mercedes sl300 convertable

Hi,
The early 300 SL suffered from dodgy HT leads and spark plugs if not regularly maintained, the problem with Mercedes Benz though is that the cars have so many features that it is almost impossible to diagnose without seeing the car. Some things to try (in this order) are : - Spark plugs, Ht leads, remove and clean Distributer Cap, replacement of HFM sensor (common fault), if none of these help then faults have been known in throttle valves and fuel pumps/filters

Happy fault finding

SOURCE: cl500 2001 merecedes

I had a similar problem with my car and was advised that the ESP and BAS normally come out as a direct result of the low voltage on the battery.Chances are your battery life has expired. Replace your battery with a new one. To remove the ESP you need to start your engine, turn the steering wheel all the way to left and right, repeat this a couple of times, switch off and restart your car.Make sure you don't leave your lightsand wipers on the auto position as this sometimes drains your buttery power unnecessarily. These simple steps should take away the frustration and make you enjoy your car again.

SOURCE: battery on mercedes A140 drains. I drove the car

aftermarket stereo? dome lights? car alarm? Use a multimeter and see what fuse has power draw when car is off.

SOURCE: 1995 Mercedes S 320 won't start. battery is fine

I know on the L.H. (previous fuel injection system) models there was a module called a base module that worked as a big overvoltage relay and powered up all the control units for the engine and drivetrain,they had 4 to 6 10amp. fuses in the top and theywould blow fuses and sometimes fail themselves causing no start conditions. I beleive yours is an H.F.M. system. I used to do roadside and i'm also a mercedes benz tech. The first thing I would try would be to put the car in nuetral and see if it starts. the nuetral safety switches of that era are problomatic. next I would check my brake light fuse in the engine compartment fuse box. That fuse also powers the starter relay-even though it doesn't state that on the fuse schematic. Also to answer your question about a lockout relay-yes there is but they rarely cause a problem. I hope I have been helpful

SOURCE: Battery drain in MB C320

Unplug the power seats.