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AA's Running EVO

Discussion in 'Android Devices' started by Selfdestruct, Jun 13, 2010.

  1. Selfdestruct

    Selfdestruct Well-Known Member
    Thread Starter

    Jun 5, 2010
    In other news (i.e., enough screen separation talk)

    How long can 4 Eneloop Rechargeable AA's run an EVO?

    Amazon.com: Sanyo Eneloop: Electronics

    First I have one of these for when I travel as a backup -- since AAs are readily available anywhere its easy to find and replace

    USB Emergency Charger / USB Battery Pack - Battery Adapter PRO

    Next I drained my Evo down to 62% when i decided to do this test

    Plugged into boxwave and charged to 100%

    Once at 100% i let it drain overnight, when i woke up the battery was 45%(yikes i only had wifi on)

    I plugged it back into boxwave (same AAs in it)

    It then charged to 68% and batteries were done

    First Test Total charge: 61% of EVO battery

    I should do a full charge and not have a break in between but i will do that eventually if anyone wants a unbroken test


  2. axisofoil

    axisofoil Well-Known Member

    Jun 4, 2010
    Rocket Scientist
    well, the question is a bit complex.
    Those batteries will store anywhere between 1500mAh and 1700mAh each on a typical charge. But they're only 1.2-1.5v depending on how charged they are.

    Short of ripping the device apart and looking at it's electronics, I would assume it uses them in series (from looking at the picture. wiring batteries in series adds their voltages, but not their total capacities) and uses them to charge the phone's battery via usb's 5v pin, so you will get around 1500-1700mAh total power available to use at 4.8-6volts, maybe less depending on how well those particular batteries charge.

    Then you have to transmit and charge the phone's battery. Li-ion batteries have realistic charging efficiencies of up to 80% or so, but depending on how fast you charge it, it can go a lot lower. Because the EVO's battery is 1500mAh, it means you're pushing it to want a single, full charge.

    So, if you charge your phone while it's off, you SHOULD get ONE full or nearly full charge from fully charged NiMH AA's. If you charge while your phone is on and/or that charger is a high current charger, you will get less, probably close to around 60% or so, as the battery will heat up, and the phone is still using power.
  3. cabbie

    cabbie Well-Known Member

    Mar 23, 2010
    I went from about 35% to 18% letting it drain overnight. Interesting. Glad I was too drunk to plug it in or else I wouldn't have noticed.
  4. Selfdestruct

    Selfdestruct Well-Known Member
    Thread Starter

    Jun 5, 2010
    Yup i guess it is much more complex haha

    Well i ran another test... ran battery down to 5% then powered EVO off

    Plugged into boxwave with 4 freshly charged batteries

    18:00 to 20:51 it was off -- LED light became Green so i turned it on thinking it was all set

    battery @ 90%

    plugged it back into Boxwave and charging again with airplane mode on

    21:07 Update: charged to 94% and AA's dead

    soooo 89% battery from 4 AAs not bad when camping or traveling when in a pinch for juice
  5. Biggest Fro

    Biggest Fro Well-Known Member

    Jan 20, 2010
    Or you could just carry a few replacement Chinese battery's in your pocket and just switch them out. :D
  6. mattcnz

    mattcnz Active Member

    Apr 5, 2010
    Would this charger have any negative effects on the EVO if I used regular disposable alkaline Energizer AA's?

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