Live cigarette socket - Mercedes GLA Forums
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post #1 of 3 (permalink) Old 04-23-2019, 03:54 PM Thread Starter
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Join Date: Apr 2019
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Live cigarette socket

Hi folks anybody been able to turn the boot power socket live all the time ? I carry a wee car freezer at times for work and need it powered all the time the freezer has a cut out if battery drops so not a problem
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post #2 of 3 (permalink) Old 05-19-2020, 12:15 PM
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Join Date: Apr 2019
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Boot 12V Socket Power

The socket in the boot is only live with the ignition on and is protected by a fuse under the cover behind the passenger foot-well carpet. I've tapped power from the fuse to power a dash cam.

If you want to ran a freezer from the socket you'll first need to ensure that the socket will deliver sufficient power. 8 to 10A max I'd say. You also need to make sure that you don't leave the car for too long such that the battery gets drained. You need to know the approximate duty cycle of the freezer. Sums required !!

Once all that is satisfied you'll need to change the source of the supply to one that is powered direct from the battery but you must include a fuse. 15 to 20A I'd say.

If you look at the fuse-holder cover you'll see a slot for a paper sheet detailing all the fuse positions. From that, you can, as I did, find the correct fuse for the boot socket. It will then take a bit of ingenuity to supply the wire to the boot from a different source. Either isolate the wire from the harness or adapt a fuse to connect to it within the fuse holder then to a permanent supply via a fuse.

Watch out if your car is still in warranty !! Hope this is of some assistance.
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post #3 of 3 (permalink) Old 05-19-2020, 01:08 PM
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Boot 12V Socket Power

I've been thinking a bit more re your freezer supply. Not knowing what it's consumption is, makes it a bit hit and miss.

I think I'd be tempted to run a separate supply direct from the battery under the bonnet via, of course, a fuse near to the battery terminal. It could be that the volt-drop on the existing socket wire will be enough to trigger the automatic cut-out in the freezer. I'd use a nice thick wire in order to minimise volt-drop. Bit of a pain but should yield a good, reliable result with little mods required to vehicle electrics. Hope this helps.
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