Watt hours is a way to measure the energy capacity of a battery pack,
so you know what to expect from your new E-bike in terms of range
performance. To calculate the watt hours (WH) of a battery pack, simply
multiply the voltage by the amp hours (Ah) of the pack. A 36-volt 10-Ah
battery pack has 360 watt hours (36 X 10 = 360). If you are nitty with
your energy usage, each mile you travel will cost you about 20 watt
hours. Therefore a 360 watt hour pack will get you about 18 miles. The
range can vary widely depending on where and how you ride.
Watt hours determine the range of your bike, the cost of your bike,
and the weight of your bike….three very important factors to consider
when buying an electric bike.
Batteries come in different cell qualities. Name brand cells such as
Samsung, Panasonic and A123 will last longer (number of charge cycles)
than no-name Chinese cells. Of course if your pack consists of name
brand cells, the cost per watt hour will be much higher.
A 250 watt motor will burn 250 watt hours in an hour and will last
you an hour and 20 minutes at full throttle on those 360 watt hours, but
it will not provide you with very much assist.
A 500 watt motor will burn through the same pack at full throttle in
less than 45 minutes, but you will be given twice as much assist as you
get from the 250 watt motor. If you are nitty with your 500 watt motor
and run it at half throttle (250 watts) and pedal a lot, you will get
the same efficiency as you get with a 250 watt motor. However the
exhilaration of available electric power is sometimes hard to resist.
36V 9Ah = 14 Miles
36V 12Ah = 22 Miles
48V 10Ah = 24 Miles
48V 17.5Ah = 42 Miles
48V 20Ah = 48 Miles