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  1. #1
    Sr. Apprentice
    Join Date
    Oct 2007
    Houston, TX

    Question How to provide more accessory electrical power?

    Folks, having just returned from our yearly trip to visit my ailing mother, with three adult children, 2 large dogs, my wife and myself in the 1990 GMC Suburban (now with 332000 miles), the need for more electrical accessory power is definitely felt.
    With portable DVD players, Laptop computers, MP3 players and cell phones, the one lone cigarette lighter adapter has serious limitations. I tried using a multiple female cigarette lighter thingy that plugged into the cigarette lighter, but the kids in the back of the car had a hard time getting juice to power their devices.
    I used a 60 watt little power inverter from Harbor Freight, which worked very well, but just didn't put out enough juice to power everyone's electronic devices.
    I am thinking of purchasing a larger inverter, but I am not sure how to wire it in.
    Ideally, I think if I attached at least one more female cigarette lighter to the rear of the center console, and if I could provide a power strip or several 110 outlets also at the rear of the center console, that would be a great solution.

    Has anyone else done this, and what has your experience been? How do you wire things in? Some things I'm concerned about with a larger, permanently wired power inverter is that someone would turn it on and after the car was shut off it would run down the battery.

    Any suggestions, help and advice are greatly appreciated, thanks so much in advance!
    1990 GMC Suburban 329,000 miles

  2. #2

    Davandy's Avatar
    Join Date
    Jun 2005
    Haasdonk Belgium


    You could work with a relay and take power directly from the battery
    Then control the relay when the ignition is on.
    I hope my explanation is clear enough?
    Peter Smet
    Haasdonk, Belgium

  3. #3


    I would agree with davandy. They make relays and contacters(solenoids) that can be triggered by an accesory wire (the switched power wire for the radio would be dandy) and tranfer large amounts of power to the inverter to provide 100VAC. However, 99.9% of power inverters nowadays have low voltage cutoff switches. The effectiveness of those switches is variable, it keeps your battery from going flat dead, but for the most part, it doesn't turn off soon enough, so you can't crank the truck back up from the battery in that state. If I were you, I'd go the relay route. Just make sure that the relay/contacter you use can pass as much power as the inverter wants to take, plus 10% or so. I've seen relays that "just barely did the job" stop working, oftentimes in the stuck on position because they were overloaded. Good luck!

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 277K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

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  4. #4
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    High Deserts of SoCal


    So far I haven't had much luck with inverters to power my laptop with. I've tried everything up to 1000watts and they won't keep up with the demand of one laptop. I didn't want to spend the money for a larger inverter so I went with a dc to dc converter since the input to the laptop is dc. The dc to dc converter gets the job done for me.

    You have to be very careful to use the proper gage wire when powering an inverter. Using wire that is too small can have disastrous results.
    There is no way to happiness....happiness is the way.:yipi:  _vXMYypuKMJFw671uF2ZPhjez_j-atRmcjM2zQKpQi1JSsB75/burb1.JPG
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  5. #5
    Sr. Apprentice
    Join Date
    Oct 2007
    Houston, TX


    Guys, I'm sorry, but I'm not at all sure about wiring in a relay, nor where I would wire it into, nor where I wold place the inverter. Regarding laptops, I have had good success with the little $6.99 60 watt power inverter sold by Harbor Freight. It worked great over the weekend to power a laptop and a dvd player for
    ~ 20 hours , but it doesn't put out enough juice to power two laptops.
    Can someone give me some specifics regarding what relay, where to wire it in, etc.? Thanks so much!

  6. #6


    this is easy and not too painfull. the first point would be the power tap is looks like the one below.

    this is behind the cover on the pass side of the engine compartment on the fire wall. there is 2 plastic bolts that hold it on. remove them and you got a good 12V power tap.
    next get one of these constant power relays.

    the 2 large lugs are the load lines (one side to the power strip and the other to the components that draw power. one of the little lugs goto a ground (Frame or neg battery) and the other to an ignition on trigger wire----the stock fuse panel or the radio power wire. i would get a 4 port cig liter plug for the other end of the load side..........mike
    Michael Collins
    1993 4X4 Suburban
    many other toys as well

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