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qwerty11's avatar
qwerty11
Explorer
May 22, 2013

Help with calculations: length of time running on battery

I need help with this as I'm getting confused. Could somebody break down the calculations to figure:

How long will a 12V battery with an amp/hr rating of Y (assuming its based on 20hrs) maintain a steady watt load of X before the battery reaches 50% discharge?

Need to build a spreadsheet I can play around with where I can change the wattage and see how long I can go.

Thanks for the help!

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  • HiTech's avatar
    HiTech
    Explorer
    May 22, 2013
    An interesting question given non linear discharge curves that vary by battery, and that constant watt loads are not constant amp. A battery that drops volts faster on discharge has to sacrifice more amps to keep constant watts. And then there is of course the non linearity of peukert losses as amp draws increase.

    But I bet there is a calculator somewhere.

    Jim

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