Power inverters, Car charging, etc.

Discussion in 'MacBook Pro' started by Papajohn56, Jul 6, 2007.

  1. Papajohn56 macrumors 6502

    Aug 13, 2005
    So I've been looking for a relatively inexpensive way to power my MacBook Pro in the car (Sub $50 preferrably), and I saw an inverter going for $30 on Amazon and at Wal-Mart. Are square wave inverters safe to use? Or do I risk damaging my computer?
  2. EngBrian macrumors regular

    Feb 7, 2007
    Ontario, Canada
    Don't have your exact answer but I was looking into this a few months ago as well. Here is the link to my thread.

    I ended up realizing that my emergency power supply in my car for boosting it also had an AC outlet and I am going to use that (haven't yet) if i need to.
  3. Papajohn56 thread starter macrumors 6502

    Aug 13, 2005
    The Pure Sine thing is what I'm wondering about. I know the MacBook Pro's power supply converts AC to DC, so I'm really taking these steps without pure sine:

    12v DC -> 120v AC Square Wave -> 18.5v DC in power supply
  4. booksacool1 macrumors 6502

    Oct 17, 2004
    I'd recommend a simple cheap ebay 70w modified sine wave inverter. The square wave ones are a bit dodgy as they emit basically a bunch of constant voltage positive and negative electrical pulses which don't approximate well to AC.

    But I've found the modified sine wave ones work well enough for laptop AC adapters and are very cheap (on ebay at least).
  5. southbark macrumors regular

    Dec 15, 2006
  6. keenkreations macrumors regular

    May 20, 2005
    I have no clue why Apple has nto made car chargers. My main concern is why Apple has not sent out the design to be used for third party manufacturers to use.
  7. amusiccale macrumors 6502

    Jun 5, 2007
    Wouldn't you want to get an inverter that can put out at least 85W, since that's what the power adapter uses?

    I've used a fairly cheap (modified sine, I believe) with my old ibook before, but that was a lower draw. Be sure your vehicle will be able to handle the extra pressure put on the electrical system--as long as you're not driving my old 88 Cavalier, you are probably fine.
  8. Papajohn56 thread starter macrumors 6502

    Aug 13, 2005

    That's one I've been looking at. 175 Watts, and a USB port so I can charge my iPod at the same time. Nice
  9. amusiccale macrumors 6502

    Jun 5, 2007
    and 175 W should be plenty--even assuming that, for a 29.99 device, that's probably a peak number--you'll be able to sustain the 85W with headroom to spare (which, in turn is a peak wattage requirement anyway?).

    Nicer than mine :) but that was several years ago.
  10. Papajohn56 thread starter macrumors 6502

    Aug 13, 2005
    According to the manufacturer, it's 150 sustained, 175 for 2 minutes at high temps, and 250 peak. This looks like a real good one.
  11. ezorc macrumors newbie

    Sep 18, 2007
    Bad behaviour with non-sine wave inverters

    We have a bush installation (Amboseli Elephant Research Project, Amboseli National Park, Kenya) with a solar system delivering non-sine wave power through a Xantrex inverter. Only problems appear to be associated with colleagues plugging in MacBooks. The following has happened: the power supply fries (older iBook); the inverter reports a short and shuts off. Our technical guy reports similar problems Mac-associated at other installations. So question: is there something special about Apply power supplies that obviate funtioning with inverter-based (esp. non-sine wave) systems. Thx for help.


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