DC to AC car adapter, can you pull too much juice?

  1. My wife wants to run her hair straightener (flat iron) in the car during long trips.
    Can this item pull too much juice and harm the car or battery?
  2. Doctor John

    Doctor John TechSpot Enthusiast Posts: 247   +15

    It would depend on the power rating (wattage) of the straightener - if you pull more than about 130 - 150W through the average car wiring, either the fuse blows or the insulation starts melting/burning! (also I would suggest not running anything mightier than 100W for more than 10 minutes per session, then cooling it off a bit).
    I trust that your wife won't be driving? ;-)
  3. SNGX1275

    SNGX1275 TS Forces Special Posts: 12,266   +218

    Your inverter isn't likely to be able to handle that. I don't know what a hair straightener would use, but I would be very surprised if it was LESS than 500W.

    Now, yes, it can be done. Those people with 12-15" subs in the back of their car are pulling 1000+ watts easy. But they do it by running a BIG fat wire from the battery, and sometimes have large capacitors involved as well (you wouldn't need caps for an iron). Also for the really impressive setups they use a much larger alternator to supply more power to/recharge the battery from the engine better than a stock one.

    So, what I'm saying is yes, you can run a lot of power off your car, but a regular cigarette lighter inverter is probably not capable of it. They make big inverters, but you'll need to run better gauge wire than what is ran to the cigarette lighter. Assuming your wife doesn't have 5' of hair, she's not going to be draining your battery down enough to cause any problems if the car is running.

    There is a possibility that your car has a "cigarette lighter" style plug that is solely for use as a 12V source for random stuff and inverters. In that case, it may run fairly hefty wire. Your car manual will probably tell you the max power you can draw from it. Keep in mind the DC to AC conversion is not 100% efficient. I don't know how efficient it is, but I'd guess ~70%.


    EDIT: My girlfriend had a straightner with 1" wide elements. I just tried it on my Kill-a-watt meter and it pulled 168W from the wall. So it isn't near as many watts as I expected. I suppose if you have a 250W inverter, and if your car manual gives a max wattage inverter you should use (and its 250W or better) then you should be good to go. If you only have a 200W, I wouldn't feel comfortable with a 168W pull from it. My gf also had a brush curling iron thing and it only pulled 98W from the wall...
  4. princevulpine

    princevulpine Newcomer, in training Topic Starter Posts: 32

    I know more know...

    I purchased a inverter, but I am going to take it back.
    The wattage of the straightener is 200W. That just TOO much juice without some heavy rewiring. Heavy to me, I'm not at all versed in the art of auto power wiring.
    So, if she is going to use a travel flat iron, I am going to look for one that is specifically designed for use in a car. I found several on amazon that has built in cord for plugging into the car. I wouldn't think that those would hurt the vehicle...


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