Power Inverter questions

Discussion in 'Mac Basics and Help' started by doubledee, Aug 25, 2014.

  1. doubledee macrumors 6502

    doubledee

    Joined:
    May 14, 2012
    Location:
    Arizona
    #1
    I am wondering if there are any "experts" out there that can shed some light on this topic...

    1.) Exactly how "evil" is one of those cigarette power inverter thingies you can buy?

    2.) Can they damage you car battery?

    3.) Can they fry your car wiring?

    4.) Can they blow up your Mac?

    5.) How long should they power my MBP when my car if not running?


    -----
    Last summer I bought a 100-watt power inverter at Target for like $50 and it was one of the best investments I ever made. (I live on the road and often get stuck working in my car, and so it is nice to have a "mobile office". I also use my MBP as a "radio" and listen to streaming audio as I work and travel, so I have a need for using my MBP in my car for "extended" periods of time.)

    Anyways, this power inverter worked great for a year until a few weeks ago it started acting up.

    I thought the male adapter was just loose, because when I would jiggle it, it would come on. But it kept shutting off or not working more and more in the past week.

    I finally decided that maybe it was going bad, so I bought a similar one - but different brand - but I am having problems with it going on and off and my screen flickering. (And this is like after I have been driving and have had the engine off for a few minutes... )


    Had my battery and alternator tested at AutoZone, and they said things were 100%.

    Bought a Sears Diehard back in January, so I think I'm doing good with my car battery.


    And based on some research last night, it seems it is better to get a heavier-duty inverter...

    (I bought another 100-watt for fear a 300-watt would fry my Toyota, but it sounds like it is better to have the larger inverter.)

    It also sounds like a 100-watt inverter is not enough to power my MBP - especially when listening to streaming audio, rendering music, or developing.

    Furthermore, it doesn't help than Apple makes cheap *ass power adapters, and the sheathing on mine cracked and so I had a bare wire before I wrapped it in electrical tape?!


    ----
    All of this is really strange behavior to me, because I often listen to a 4-hour radio show (e.g. AT40) with my engine off, and maybe once an hour I start things up for 5-10 minutes.

    My old inverter always supplied enough juice - even with 15 apps open - and when my car was running, it would take a dead MBP battery and charge it up completely in maybe 2 hours. (That's about as good as being plugged in to the wall.)

    Never once did I feel the old inverter wasn't doing it's job.


    So, I am hoping that I just wore out that Target power inverter, and maybe the new Duracell one I got isn't as good and I just need a larger wattage one?


    What do you think about all of this?


    To me, it should not be that hard to power a laptop from my car whether it is running or off. (Especially if I am just checking e-mail or surfing the Internet.)


    Thoughts?

    Recommendations?

    Sincerely,


    Debbie
     
  2. superbovine macrumors 68030

    superbovine

    Joined:
    Nov 7, 2003
    #2
    1.) Exactly how "evil" is one of those cigarette power inverter thingies you can buy?

    not "evil" like a gremlin. "evil" like gizmo.

    2.) Can they damage you car battery?

    unlikely

    3.) Can they fry your car wiring?

    possible to prevent buy a lighter extension cord with an inline fuse.

    4.) Can they blow up your Mac?

    if a battery gets to hot it will explode or catch fire. However, this is unlikely and will have more to do with a bad battery.

    5.) How long should they power my MBP when my car if not running?

    no idea the factors included are what else is on, your battery condition, and how much you are using the lappy.

    You issue is the amp rating on your inverter.

    watts = volts * amps

    Standard US home electric socket is 15-20 amps depending on the age of the house and local electrical code.

    Depending on what inverter you bought, it might be only 2.1 amps etc. You need to read the specification for the amp of the inverter and the amp requirements for your MBP.

    My guess is without having hooked-up a multi-meter to it is that you are over drawing on your amps causing the behavior.
     
  3. glenthompson macrumors 68000

    glenthompson

    Joined:
    Apr 27, 2011
    Location:
    Virginia
    #3
    2- only if you let it completely discharge your battery.

    3- not if it is properly fused.

    4- as long as you're using the apple charger there should be no problem.

    5- typical starting battery is about 100 amp-hours. If you're drawing 120 watts that's 10 amps. Figure on 5 hours before reaching ½ charge which is the lowest you should go. If anything else is on add that in too.

    There are two type of inverters, modified sine wave MSW and pure sine wave PSW. Some devices don't like the cheaper MSW like heating circuits and some motors. A PSW costs more but provides cleaner power.

    I find it easier to load all my podcasts, audiobooks, music onto my iPhone and use it. Much lower power drain, easier to recharge, and easier to transport.
     
  4. doubledee thread starter macrumors 6502

    doubledee

    Joined:
    May 14, 2012
    Location:
    Arizona
    #4
    So if I was recording a 4-hour show, and I ran my car every hour for maybe 5 minutes, I should be more than okay?


    The point is if I am traveling and my show is on, the only way to listen to it is in my car.

    And since I also record shows using Audacity, that does make my MBP work much harder than just surfing.

    Sincerely,


    Debbie
     
  5. chown33 macrumors 604

    Joined:
    Aug 9, 2009
    #5
    Does the battery in your MacBook Pro not hold a charge?

    My MBP can run on its battery for at least 4 hours, so I'm wondering why you don't run from the Mac's builtin battery, instead of running it from the charger plugged into the power inverter.
     
  6. doubledee thread starter macrumors 6502

    doubledee

    Joined:
    May 14, 2012
    Location:
    Arizona
    #6
    It seems to do pretty good - maybe not quite as good as when it was brand new last March 2013.



    Because if I am listening to streaming audio in FireFox and recording things in Audacity, I don't think that I could get more than 2 - 2 1/2 hours out of my battery.

    (It's pretty processor intensive to record, and even more so to render music.)

    In addition, when I am listening to my radio shows, I am also working on my website, so you have to add in MAMP, NetBeans, OpenOffice, TextEdit, several Finder instances, plus several other apps...

    That knocks down my battery time of use even more!


    By contrast, if my battery was 100% charged, and I was just using FireFox to check e-mail, surf, and maybe post on MacRumors, then I could probably get 4 - 4 1/2 hours.

    Even when I have FF, MAMP and NetBeans open, I think I can usually get 4 hours.

    The streaming audio and Audacity is what kills things.

    Sincerely,


    Debbie
     

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