Question: how much power do you need to charge a car battery?
Answer: A basic charger usually charges at around 2 amps - and so needs 24 hours to deliver the 48 amps needed to fully charge a flat, 48 amp hour battery. But there is a wide range of chargers with different charge rates on the market - from 2 to 10 amps. The higher the charge output, the faster a flat battery is recharged.