In most cases, how much current a car radio draws is approximately ten amps.
Another way to think about the electricity draw is as an hourly rate. The average power draw from a car radio is 0.02 kWh per hour. In simpler terms, that’s not much more power than a small LED light! Of course, a drive-in movie might be several hours long—and that could draw the battery down quite a bit, especially if you drive an older car.