48-Volt Mild Hybrid Systems: Mercedes-Benz

Mild hybrid systems are not new. They were some of the first hybrid vehicles to be put into production. The 48-volt mild hybrid system is now becoming more common among some vehicle makers. What consideration are there for repairing a vehicle equipped with a 48-volt mild hybrid system? Let’s see what Mercedes-Benz has to say.

Mercedes-Benz introduced the 48-volt system on late model vehicles equipped with a 256 or 264 6-cylinder engine. The 48-volt system is used to support systems such as the stop/start function, coolant pump, electric refrigerant compressor, and heated windshield. This helps reduce fuel consumption, aid in performance, and provide additional occupant comfort.

Per the Mercedes-Benz 48 V On-Board Electrical System Technology Guide:

"For this reason, the 12V on-board electrical system remains virtually unchanged. It is merely supplied by a 48V/12V DC/DC converter instead of by a 12V alternator."

Per Mercedes-Benz vehicle-specific repair information, Notes On Battery:

  • "A 48V connector may only be unplugged in de-energized state. The 48V on-board electrical system is de-energized if the 12V battery is disconnected for longer than 10 s."
  • 48V ground line is colored brown and purple

The OEM Hybrid and Electric Vehicle Disable Search features a battery layout and step-by-step directions to locate the procedure to disconnect the negative battery cables.

For additional Mercedes-Benz information, check out the Mercedes-Benz OEM Information page.

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