Power calculation
An ebike's power is typically measured in wattage. This can easily be calculated using Ohms' law where:
watts = max amps of your controller x voltage of your battery
If for example you have a 36V battery and a 14A controller, then your Max W=36 x 14 = 504
An ebike's power is typically measured in wattage. This can easily be calculated using Ohms' law where:
watts = max amps of your controller x voltage of your battery
If for example you have a 36V battery and a 14A controller, then your Max W=36 x 14 = 504
How much power do you need
The answer depends on a number of factors:
In Johannesburg, which is pretty hilly, my wife, who weighs around 60kg rides an ebike with a 36V 250W motor (actual max wattage is 504W) and she manages perfectly well. This is actually the maximum configuration that is allowed to be sold in Europe and the UK, irrespective of rider weight.
If you think of it, it is a lot of power. A tour de France rider can typically sustain around 350W for about an hour and a bit over 400W for 30 minutes. So, you can think of a 250W motor as the assistance of a fit rider who weighs nothing.
I weigh about 100kg and can easily manage with a 48V 500W motor (with a maximum wattage of 1,056 (48V x 22A). However, I have opted to install a 48V 750W motor giving 1,200 maximum watts), simply because I'm ma lazy rider.
The answer depends on a number of factors:
- your weight
- the terrain you'll be riding - tar vs dirt and loose sand, flat vs hills
- how fit you are and how much assistance you want from the motor
- whether you'll be riding into head winds
In Johannesburg, which is pretty hilly, my wife, who weighs around 60kg rides an ebike with a 36V 250W motor (actual max wattage is 504W) and she manages perfectly well. This is actually the maximum configuration that is allowed to be sold in Europe and the UK, irrespective of rider weight.
If you think of it, it is a lot of power. A tour de France rider can typically sustain around 350W for about an hour and a bit over 400W for 30 minutes. So, you can think of a 250W motor as the assistance of a fit rider who weighs nothing.
I weigh about 100kg and can easily manage with a 48V 500W motor (with a maximum wattage of 1,056 (48V x 22A). However, I have opted to install a 48V 750W motor giving 1,200 maximum watts), simply because I'm ma lazy rider.