Friday, October 6, 2017

Installing Coach Battery Powered 12-volt DC sockets on Sprinter Dashboard

My 2011 Agile has two factory 12-volt DC sockets located in the cab, one by the pull-out cup holder (only powered when engine is running) and one just below the pull-out cup holder which is always powered. The MB factory sockets are wired into the chassis battery.

I installed 2 additional 12-volt DC sockets for charging our phones/ tablets/ cameras/etc. I wired the new sockets from the coach battery so as not to put extra drain into the starting battery when we are out dry camping. The additional sockets were installed on the outer sides of the dashboard top vents thus minimizing charging cables clutter hanging from the dashboard and interfering while driving. I opted for 12-volt DC sockets and use plug-in USB car chargers in lieu of surface- mount USB charger sockets for more universal mobile charging approach. Also replacing a malfunctioning USB charger with our setup would be much easier, not so with the surface- mount USB charger sockets.

Things you need:

Tools needed:

First is to remove the center dashboard trim, use nylon trim removal kit or equivalent to prevent marring or damaging the plastic trims. Green arrows points to dashboard center trim retaining holes, you can easily pop the center trim out using a trim removal tool.

Once the center trim is removed, unscrew 4 Philips head screws that holds the side trims (pointed by green arrows above).

The 4 retaining locking tabs (pointed by green arrows) releases easily by gently tugging on the trim towards you. One of the locking tabs located on the upper top left needs a little coaching to release. Once all 4 locking tabs are off, the plastic side trims easily slides out towards you (notice the L-shaped retaining tabs circled in green).

The top vents (both sides) can be easily removed by gently pulling it towards you.

With the top AC vents removed. Carefully mark the preferred location for the 12-volt socket so it clears the AC vent  before  drilling any holes.

With the driver side 12-volt DC socket mounting hole done. Due to limited space to maneuver a drill, I use a 90- degree drill attachment and step-drill bit to make this hole.

With the driver side 12-volt socket wired.

The  new 12-volt sockets (+) wire with inline-fuse is tapped from the Coach Battery Disconnect Relay which is located under the driver seat. The ground is wired to a factory ground point located left of the MB fuse box next to the driver foot rest.

The MB two fuse holders needs to be unscrewed from the seat base to access the Battery Disconnect Relay. A 3/8" ring terminal crimp connector is used to connect the in-line fuse to the Battery Disconnect Relay switched power post.

The positive wire from the relay is then routed behind the foot well plastic trim (needs removal) then  under the dashboard to the new installed 12-volt sockets location.

The passenger side 12-volt DC socket.

The driver side 12-volt DC socket with USB car charger plugged in.

My new wireless car charger mounted next to the cup holder using a very sticky suction cup mount.

Sporting my dinosaur Note II phone with added wireless charging capability.

For our newer phones, like the S8/9 which is Qualcomm Quick Charge capable, I use this one "Fast Charger QC3.0". The USB QC3.0 charges the Samsung S8 and S9 pretty quick. The charger comes in 2-pack for about 12 bucks, you can't go wrong with that price. I also bought a heavy duty Nylon Braided USB Type-C Charging 3.0 USB-A to USB-C cable from Amazon, a quality made cable for $12 (Two 6-ft cables).


  1. Excellent write up. I completed this mod a couple of weeks ago. Using your instructions, very easy to complete. What a difference not having cords catching on our feet as we get up from our seats! Made our trip this weekend that much nicer. Unfortunately on this trip it sounded like the macerator blades tore up. I can hear the motor running but no flow. So I will be using your macerator removal instructions shortly.

    1. Thank you. Make sure it's the blade and not something else because replacing the macerator blade is a PITA to do.

  2. Great write up and mod for the reasons already mentioned. Not having cords all over the floor or getting in the way. Thank you!!

    1. You're welcome and thank you too for the compliments.


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