Work out battery charge cost instantly with clear inputs, formula shown and shareable results.
Stored energy is capacity in amp-hours times voltage, and the charger draws more than that because of conversion losses. A 5,000 mAh phone battery holds 19.3 Wh, draws about 24 Wh from the wall, and costs well under a penny to charge.
Charge cost
stored Wh = Ah x V; drawn Wh = stored / efficiency; cost = drawn kWh x tariff
Because 24 Wh is 0.024 kWh. Charging a phone every day for a year costs around two pounds — less than a single takeaway coffee.
Heat, in the charger and in the battery itself. That is why both get warm during fast charging.