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Help Needed: 12V SLA Battery to Charge a Phone

Discussion in 'Power Electronics' started by montclair, Jun 7, 2013.

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  1. montclair

    montclair

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    0
    Jun 7, 2013
    Hi Everyone,

    I'm going to be away from wall power for 10 days at the BSA National Jamboree. I want to bring a 12V SLA battery to charge my smart phone at night and possibly a tablet, too, but not as frequently. They advise that there will be charging stations, but I'm not going to rely on that.

    I'm going to go device > car charger > car charger socket with alligator clips > 12V SLA.

    My car charger's output is 5V and 950mA.

    Where I'm stumped is the size battery I will need. I will be hiking in from the drop off area to our camp site, so I need to be somewhat conservative with the size.

    Any help would be greatly appreciated.

    Rich

    EDIT:

    OK, maybe I just answered my own question. My phone's battery is 2100 mAh. Do I just divide that number into the mAh of the battery to get the number of charges? For example: a 7000 mAh battery would charge the battery from 0 to full capacity +/- 3.33 times?
     
    Last edited: Jun 8, 2013
  2. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
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    May 8, 2012
    I don't uderstand this. How are you going to charge a 12V battery from a 5V charger?

    Chris
     
  3. montclair

    montclair

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    0
    Jun 7, 2013
    It's the other direction.
     
  4. donkey

    donkey

    1,293
    56
    Feb 26, 2011
    if you are truly worried about weight then I would steer away from SLA battery. the smallest I have seen is about 7.2Amp hours, and its a half decent weight. about 2kg
    try http://www.ebay.com/itm/NEW-Dynamo-Hand-Crank-USB-Cell-Phone-Emergency-Charger-/300593826063
    this has the added bonus of being able to give you unlimited power as long as you are winding.
    there are other ways to do it but they rely on so many things that need a source (eg solar you may not have sun)
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    651
    May 8, 2012
    Ah, now it makes sense.

    Chris
     
  6. montclair

    montclair

    3
    0
    Jun 7, 2013
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