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The Challenge: Recharge a Battery

What voltage are car batteries?

Car batteries are made up of six 'cells' each giving a voltage of 2.2 volts (2.2v) when fully charged and about 1.8v when discharged. When a car battery is fully charged it has a voltage of 13.2v. So to fully charge a car battery we somehow have to produce a voltage of at least 13.2v (we'll aim at 14v) and force this back into the battery.


Row of cells in series