When considering any kind of EV, one of the first steps is to determine how much power your vehicle will need to attain the desired speed.
The power requirement is mainly a function of speed, wind resistance and hill climbing power. Keep in mind that wind resistance is both headwind and speed added.
As speed increases, the wind resistance increases exponentially. Below 10mph, wind resistance can be largely ignored.
Hill climbing power requirements are a function of total vehicle weight and grade (steepness). These relationships are linear.
Below is a chart based on "typical" values. If your weight is substantially more, the power requirements will be more.
You can use one of the many EV calculators to punch in your specific numbers. Here are a few:
http://www.kreuzotter.de/english/espeed.htm
http://www.ebikes.ca/simulator/
http://www.geocities.com/CapeCanaveral/lab/8679/evcalc.html
http://endless-sphere.com/forums/viewtopic.php?t=538
The power requirements are "at the wheel" with most of these calculators. This is ususally how most electric motors are rated.
To find the power requirements of the batteries, we must factor in efficiency. The batteries must supply more power than what you get at the wheel due to losses. In some cases the losses can be huge. At best, with typical bike motors, you'll be in the 80-85% range.
Climbing hills where the motor bogs down, or running too high of a gearing can cause the efficiency to drop below 50%. This is bad. Not only are we wasting half the power under these conditions, the half we're wasting goes into heating up the motor, which can overheat or destroy it.
The power requirement is mainly a function of speed, wind resistance and hill climbing power. Keep in mind that wind resistance is both headwind and speed added.
As speed increases, the wind resistance increases exponentially. Below 10mph, wind resistance can be largely ignored.
Hill climbing power requirements are a function of total vehicle weight and grade (steepness). These relationships are linear.
Below is a chart based on "typical" values. If your weight is substantially more, the power requirements will be more.
You can use one of the many EV calculators to punch in your specific numbers. Here are a few:
http://www.kreuzotter.de/english/espeed.htm
http://www.ebikes.ca/simulator/
http://www.geocities.com/CapeCanaveral/lab/8679/evcalc.html
http://endless-sphere.com/forums/viewtopic.php?t=538
The power requirements are "at the wheel" with most of these calculators. This is ususally how most electric motors are rated.
To find the power requirements of the batteries, we must factor in efficiency. The batteries must supply more power than what you get at the wheel due to losses. In some cases the losses can be huge. At best, with typical bike motors, you'll be in the 80-85% range.
Climbing hills where the motor bogs down, or running too high of a gearing can cause the efficiency to drop below 50%. This is bad. Not only are we wasting half the power under these conditions, the half we're wasting goes into heating up the motor, which can overheat or destroy it.