Install an Extra Car Charger




Introduction: Install an Extra Car Charger

How many times have you been in the car with the kids, or your homies, or that hobo you picked up hitchhiking, and suddenly everyone and their brother needs to charge their phone... o_O and then to make matters worse you have to stretch a cable all the way to the back seat to be passed around like two scuba divers on one tank of air. and of course you didn't need the 5ft cord, the 12inch one is you have a voltage deficient hobo squeezing between the front seats so he can check his status updates while his phone charges.....
Let's fix that..

Step 1: Finding a Power Source

So the idea here is that we don't want to run wires from the front of the car. but most of the wiring running to the back is for the signal light....let's not mess with those.
Fortunately there is an alternative for most of us, the trunk light.
Now in my case, and I suspect yours as well, my trunk light uses a 12v bulb. Perfect! That's the same voltage as your cigarette lighter!

Step 2: Connecting Your Charger

Once you know where you are getting your power from you need to convert it to something you can use. I wanted to keep this simple.
Since the trunk light uses the same 12v as the cigarette lighter then we can just use a regular car charger.
I am using a Belkin car charger I got from Wall-mart. but any charger will work for this. I do recommend a 2.1 amp charger just cause the extra wattage does charge the phone faster then the standard 1amp veriety.
Now, to wire this up is really simple. Red is positive + and Black is ground/common. If you look at the picture, the tip is positive (red) and the side is ground (black). Most of these have two side contacts but both are ground.

In my case I dismantled the light fixture and incorporated the pieces but honestly you can just run long enough wires to connect the contact from the light bulb to the charger.

Step 3: Cut a Hole

If you look at the previous step the charger I am using flairs out at end. so it was perfect for this I just cut a small whole in the rear window ledge and pressed the charger in. But as you can see it is metal under the felt. There was already a hole

Step 4: Finishing Up

Once you have your leads (wires) soldered to the car charger thread it through the whole and connect them to the contacts for your light bulb. MAKE SURE YOU CONNECT RED TO POSITIVE AND BLACK TO GROUND!!!
And that's ......

Step 5: One More Thing

You also might want to ground out the latch switch. or else you can only use your charger when the trunk is open... like when the light is on.



    • Water Contest

      Water Contest
    • Tiny Home Contest

      Tiny Home Contest
    • Creative Misuse Contest

      Creative Misuse Contest

    13 Discussions

    At Step 3:

    it is called a "Hole" not a "Whole"

    Feel free to delete this comment after correcting ^^

    1 reply

    Would this only supply power if the trunk lid was open? Would you need to splice into the line leading to the switch instead of the bulb?

    1 reply

    in all honesty I am not 100% on how the latch switch works. I played around with it and figured out that the circuit is closed when a contact in the latch is grounded. So (as you see in the last step) I grounded the connector to the trunk lid. this had the side effect that the the charger Is still running even when the car is off. which I think means it's grounding out the battery but it seems to be negligible I've had this set up for a week now and there doesn't seem to be an effect on the battery.

    Great idea, although the only thing I would warn is the amount of current you draw. A phone should be fine but heavier draws (a cool box for example) might draw enough current to melt the wires

    1 reply

    Most definitely. I am probably going to rewire it for a port. The wire I am using I'd pretty heavy Guage solid core so it should handle most loads just fine. My alternator only puts out 90 amps so I can't run anything too big of of it anyway.

    Now this is a great instructable!
    Very simple to do and cheap too.
    I like it!

    3 replies

    Thanks Joe. I'll be adding more soon. any feedback is always appreciated.

    I'm working on my boat this weekend. Might just install one of these.