• Question: How many AA batteries would it take to power a phone for a year?

    Asked by nessie to Saiful, Petra, Jenny, Jawwad, Iain, Bethan on 19 Jan 2017.
    • Photo: Petra Cameron

      Petra Cameron answered on 19 Jan 2017:

      This is actually quite hard to answer!
      My phone has a 3000mAh battery and I normally charge it every 24 hours. AA bateries vary a lot , but a typical alkaline battery might be 2000 mAh. mAh is a measure of the charge (Q=it) that can flow out of my battery in an hour. However this doesn’t help us too much as we need to know how much energy the battery can deliver (in Joules) – which is measured by multiplying the instantaneous voltage by the charge (J=VxQ) and integrating over the time the battery is discharging. This will depend on how much I am using my phone and how much current it is drawing. An AA battery has a voltage of ~1.5V. A phone battery is more like 3-4 volts. So for a start you would have to connect at least two AA batteries in series to get a high enough voltage to run your phone.

      As a very rough estimate I would therfore say you need at least 1000 AA batteries to make the phone run for a year!

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