Power (Watts)

Electrical power represents the overall value of electrical energy based on both the Voltage and Current, so the overall energy measured in Watts and is simply:

(Volts X Amps = Watts)

Devices that consume electricity, known simply as 'loads' are usually rated by Wattage (such as lamps for example) this refers to how much overall energy the device consumes, and offers some indication of how much work the device will do. However devices that provide a source of electricity, such as batteries, cables and fuses are rated by the current they can carry in Amps. For this reason we need to be able to work out the Current based on Wattage ÷ Voltage, and the wattage based on voltage X current. The video lesson below covers this in great detail.



  • 1200W load on a 12V supply will consume 100 Amps (1200 / 12 = 100 Amps)
  • 1200W load on a 24V supply will consume 50 Amps (1200 / 24 = 50 Amps)
  • 1200W load on a 48V supply will consume 25 Amps(1200 / 48 = 25 Amps)
  • 1 X 50Ah 12V Battery contains 600Wh of energy (50 X 12)
  • A 10A load on a 12V system is 120W (10 X 12)