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Thread: Power tablet via Radio Wiring Harness

  1. #1
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    Power tablet via Radio Wiring Harness

    I'm trying to keep costs as low as possible for a carPC, so I'm gonna go with a Galaxy Tab 2 7" (unless there are better options). My question is, can I splice up a car charger to the 12v constant line on the factory radio harness, and use a relay on the switched line to turn it on and off with the ignition? This seems likes the cheapest, and nicest way to power the tablet.

  2. #2
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    Is there a reason you do not want to plug the car charger into the cigarette lighter?

    that would be the cheapest option.

    only reason not to, that i can think about, is if the cigarette lighter port does not turn off at all.

  3. #3
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    Quote Originally Posted by trinybwoy View Post
    Is there a reason you do not want to plug the car charger into the cigarette lighter?

    that would be the cheapest option.

    only reason not to, that i can think about, is if the cigarette lighter port does not turn off at all.
    Its going to be a permanent installation, so it would be pretty ugly if I ran a wire out of the dash. I guess I could splice into the wires for the cigarette outlet...see its going to be in an Acura RSX, which I don't own yet, so I'm not sure if the cigarette outlet never shuts off. I know in my current car its always-on.

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    Plus, I'm not sure how many amps the cigarette outlet puts out, I also have an AC inverter that plugs into the cigarette outlet, so I don't want to waste some off those precious watts on the tablet, and end up blowing a fuse on the line, if I can power it from the harness.

  5. #5
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    for a permanent install, i would heavily recommend running a new power wire from the battery. it is perfectly fine to use the acc wire to trigger relays and amp turn-ons, but i don't like relying on factory wiring any more then i need to. there are a ton of variables to using the factor wiring for stuff like this. you might save a few pennies now, but it could cost hundreds of dollars later if you happen to damage the wire or the car adding a load that the car's wiring wasn't designed to handle.

    for instance, in my car, there is a 10A fuse for all the accessories in the car(i know of this fuse because i've blown it more then once 'troubleshooting')-- so by the time you factor in the draw of all the other components, what started as a 10A fuse now only looks to have 2-3A available at the very most, which is usually not enough overhead for certain devices..

    i have used walmart wiring kits in the past-- most are under $20, and they do the job fine.

  6. #6
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    I figure it can't draw more power than a factory/aftermarket head unit would, and I won't be having a head unit. So load on the circuit shouldn't be an issue right? a 5v 2A charger is drawing 10w...a head unit operates at 12v so it would need to draw 833ma to draw the same amount of current. I guarantee you it draws more than that.

  7. #7
    Raw Wave
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    If that radio circuit is capable of the Amps required, fine. (Old constants were low current "memory only". These days it seems the ACC or IGN +12V are sensing only with the "constant" supplying the main power - ie, 10A fuses/circuits or higher.

    I assume you have a switch or circuit to turn it off?

  8. #8
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    My plan was a relay on the ACC line, so it was only on when the car was on.

    EDIT: Free from mod verification on my posts. Feels good...

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