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Recharging Laptop From Plane Headphone Jacks? 19

Posted by Cliff
from the is-there-enough-current-for-the-job dept.
krow asks: "So every flight I get on I wonder, could I partially recharge my laptop off of the headphone outlet? What about using alligator clips to the recharger for the airphone? Anyone else have some creative ideas? How much juice do you think you could pull before tripping a breaker?" Well, this was a fun question for once. I've always wondered the same thing but figured the current/voltage would be insufficient for anything more than a trickle charge, if even that. Anyone have any clues? Or better yet ... anyone have alligator clips for those wacky Airphones?
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Recharging Laptop Batteries From Plane Headphone Jacks?

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  • its entirely possible, it's similar to the inverters that let you run 120 volt devices off of a car battery. the problem is that its designed as a data transfer where the power is varying in intensity and duration. you'd first have to find some way to get even power, then find a way to store/magnify it to produce enough juice. i can't see powering a laptop but maybe a personal organizer or palmtop/handheld device. we must also consider the more important question: if theres an R rated movie on and your computer isnt 17 would it still be allowed to plug the headphones in? nevarmore (my slashdot login doesnt always work from this computer)
  • why not just use the 120v outlet on most planes?

    Well, most - actually all - planes I've been on have not had 120 VAC outlets available for me to use. It could be that I always fly economy...

    First class seats probably do have outlets almost all of the time, but people who can afford to fly first class can probably afford an extra battery or two for their laptop.

    -mdek.net [mdek.net]
  • Then you just need a daytime flight with a north facing window (or east in the morning, west in the afternoon). Oo, that's for the Southern hemisphere. Northerners'll need a south facing window maybe...
  • Several of the planes I've been on have 12v car 'cigarette lighter' plugs between the seat cushions near the knee. Usually seats which have it are marked with a sticker on the label by the row number.

    As for headphone jacks, I dont think you could get any real power out of those. Usually its a standard 3.5mm stereo headphone jack.

    They never show R-rated movies on planes. Dont forget the screen can be seen by everyone, and usually the r-rating is for the video, not audio.
  • by Christopher Thomas (11717) on Friday December 29, 2000 @10:42PM (#1420861)
    Trying to pull that much power from a headphone jack would probably blow the buffer or amplifier that's on the other end. The headphone jack on your typical sound card, for example, is only specced to about 4 watts. Your computer consumes much more power than that, and the power consumption for charging will be comparable to this or greater than this (unless you want to spend far more time charging than using).

    OTOH, if they wired the headphones the cheap and crappy way (in parallel), you can pull a fair bit more power without damaging anything... as long as nobody else is trying the same stunt. YMMV. I wouldn't risk it.

    An outlet that's specifically designed for charging other devices might be more practical, but bear in mind that something like an airphone probably has lower power consumption than your computer, and the charger will thus be specced for lower power on charging (no reason to charge it faster than, say, 4x usage power consumption [random figure]).

    Lastly, if you have a power converter in your charger (as is likely), you'll probably be producing a lot of RF noise during charging (as most compact power supplies/power converters are switched at high frequency to let you make inductive components smaller).

    My advice: Shell out for an extra battery.
  • by stubob (204064) on Friday December 29, 2000 @11:16PM (#1420862) Homepage
    But don't all Slashdotters get aisle seats because they hate Windows?

    -1, groaner. The current moderation system is boring.
  • by Anonymous Coward
    Most planes I've been in use non-standard headphone jacks so people don't steal the headphones...It's not even an electrical connection, the headphones are like a stethoscope and the speakers are directly in the chair's armrest...
  • At least, it is for my laptop. If you happen to have a Dell, try here [dell.com] for some options. Other manufacturers, ask your OEM.
  • I know that this sounds wacky, but in the bathrooms on most planes (at least ones designed for transoceanic flights) there is usually an outlet for plugging in an electric razor. I have actually used them to charge up a laptop, and I bet they would work even better for something like a Palm that charges in the cradle. Or, maybe you could work out a deal with the flight attendants to let you use one of the outlets in the galley (kitchen area). There's usually a couple there. Good luck.

  • The EmPower jacks on airplanes are 15V, not 12V. Web searches for "airplane power notebook" will show you many manufacturers of power adapters for those jacks. Or use an EmPower-to-12V [laptopproducts.com] adapter with your notebook's car adapter.
  • by MemRaven (39601) <kirk AT kirkwylie DOT com> on Saturday December 30, 2000 @10:41AM (#1420867)
    The jacks that those will work with are specific recharging ports available on some airlines. Specifically, I've NEVER seen them in coach. In business class on international flights, I see them all the time. But even First Class on domestic flights seldom have them (flights are too short to make them that worthwhile, and they haven't upgraded the seats up there to the seats they can charge an extra $5k for).

    The specific question is whether you can charge your laptop on something which was not designed for it, and probably something you're going to find in Coach class.

  • Some airlines actually hand out adapters if you ask for them, so that you can use your own headphones. I've also been on one that handed out regular headphones as well as adapters so that you could use them with the plane's dual plug system. And, you can always use your own headphones without an adapter if you don't mind mono.

    --

  • Flight Engineer: "Three lavatories have been drawing 9 amps for 15 minutes. Tell the flight attendants to ask lavatories 3, 4, and 6 to quit playing wireless Quake or we'll have to turn off all their power."
  • Buy an extra battery. I'm not sure about anyone else, but I don't think I want you ripping into panels with alligator clips digging into the electrical system of a plane that I'm on. Call me a wimp.

    Two batteries will get you across the country on just about any modern laptop.


    http://www.superiorlabs.com [superiorlabs.com]
  • Flight Engineer: "Three lavatories have been drawing 9 amps for 15 minutes. Tell the flight attendants to ask lavatories 3, 4, and 6 to quit playing wireless Quake or we'll have to turn off all their power."

    Very cute, however...
    You know the part in the in-flight safety lecture where they tell you not to use any cellphones or other broadcasting devices? I think that would turn the conversation into something like:
    Pilot: "WTF! What's all the static on the air-to-ground loop? Where's my radar? The radio system is crapping out!
    Flight Engineer: "Three lavatories have been drawing 9 amps for 15 minutes. Tell the flight attendants to ask lavatories 3, 4, and 6 to quit playing wireless Quake or we'll have to turn off all their power. Oh, and tell the ground control at <destination> to get the police ready to arrest the three guys for reckless endangerment."

  • Actually, that's incorrect. That's a TAKEOFF saftey precaution, not inflight.

    And it has to be BS - consider - if it were REALLY a problem, they wouldn't let you carry them onboard. Are you REALLY going to risk a plane on the possiblity that some moron doesn't turn off his cell phone and receives a call??????
  • The 767 has one 120VAC outlet on each side in coach, which is powered during flight. It's on the floor under the window, forward of the wing -- about halfway to the cockpit bulkhead. (Exactly which row this is depends on how the airline configures the seats.) Other planes may also have such outlets, but you won't know if you don't look.
  • Unfortunately, anytime I've flown, the flight attendants insist that the windows be closed, to improve the viewing experience for the inflight movie... needless to say, it infuriates me every time.

    "...the people who are crazy enough to think they can change the world are the ones who do."

  • I have my laptop set up not to suspend when I close it. The screen will turn off, though. I get an extra hour or so listening to MP3s.

    You could also decrease power usage by removing PCMCIA cards.

    Also, if you have the patience, set up a RAM disk and store MP3s there. Then set it up so that the hard disk isn't used so much (look for cron jobs, and see the Battery-Powered HOWTO). Set up APM to power down the disk quickly.

Dennis Ritchie is twice as bright as Steve Jobs, and only half wrong. -- Jim Gettys

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