What are WATTS ?
Once we know the voltage (or pressure) and current (or volume), we can calculate the power , or wattage by multiplying the two figures together. The number of watts in a system is the most important figure of all, because it defines the power output. A few examples: The Zap motor draws 20 Amps x 12 Volts = 240 Watts The Giant Lafree Lite draws 15 Amps x 24 Volts = 360 Watts The Powabyke draws 20 Amps x 36 Volts = 720 Watts The Curry Drive draws 80 Amps x 12 Volts = 960 Watts Not surprisingly, the Curry is the fastest motor, followed by the Powabyke and the Lafree, with the Zap coming in last. Note that the Giant Lafree draws the smallest number of amps, but the highest voltage. Note also, that the Curry Drive is the fastest, but has the lowest voltage. It's impossible to calculate the power without knowing both the number of amps and volts. I thought the legal limit was 200 Watts in the UK? Well, yes and no. The legal limit refers to the maximum continuous power output, whereas the figures above are for absolute maximum power. Most motors can give a high output for a minute or two, but they'd melt if asked to do it all day - just like a cyclist.