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Why can't I charge my phone by holding it and shuffling my feet across a carpet? (lemm.ee)

submitted 1 week ago by [email protected] to c/[email protected]

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[–] [email protected] 10 points 1 week ago

That will generate a high voltage, extremely low amperage static electric buildup along the friction surfaces.

We’re talking about 4KV, 1.2 mJoules for 10^-5^ amp seconds.

Phone chargers contain 2400mAh of charge running 5 volts at 3A.

So somehow, you need to convert an ultrahigh voltage and minuscule amperage to a low voltage and relatively high amperage over an extended period of time. You’ll lose some energy in the conversion, and as a result, you’d have to have around 300 people feeding power into the charging circuit with their feet, over an extended period, to build up enough power for a measurable charge.

You’d do better to charge it using a stationary bike and a dynamo, which results in significantly less conversion loss. Or, for that matter, a swing dynamo that generates current from the swing of your walk (some old watches do this).