ZAP Donates Charger to University of Michigan Bike Project

ZAP Donates Charger to University of Michigan Bike Project

Dear ZAP:

On behalf of the University of Michigan school of Mechanical Engineering and the Environmental Protection Agency, thanks a bunch for sponsoring our team with a battery charger. We are developing a hydraulically powered, 2-person, 3-wheeled vehicle, and needed some way to charge the 3-12 volt batteries that power the electronics on the bike (HPV).

The EPA is sponsoring the grant to UofM, and the generous help of companies like ZAP will really make the vehicle a success. Our facility has been developing hydraulics for hybrid motor vehicles for over 7 years. Hydraulics are nothing short of awesome for efficiently storing braking energy and 0-30mph launching power for vehicles. The students came to us almost 2 years ago and proposed that we use this technology for making hill climbing and stop-and-go traffic easier for bicycle applications.

For their 2-seater demonstration tricycle, the hydraulics can store 95 percent of the braking power from 20mph down to 5mph. And then releasing this energy makes for a very efficient and powerful launch from 0 to 20mph in just over 4 seconds (about 200ft-lbs launching force!). It's nothing short of exhilarating. Once up to cruise speed, the hub-motor maintains the speed. During cruising, or at a typical 1-minute stoplight, the passengers can continue to pedal pump up the accumulators for successive launches or for hill climbing.

Here's a simplified energy explanation: The average human can easily pump at a power rate of 1/3 of a horsepower (250 watts). Two people pedaling for one minute gives a 2/3 horsepower-minute (or 40 horsepower-seconds) of energy. Releasing this energy with some stored pedal assist over 4 seconds provides a 10 horsepower launch (on Free energy), without the exhaustion. For a bike, we figure that with state-of-the art technology and some smart packaging, a regenerative package could fit within a shoebox and weigh about 20lbs.

The shell will be made for the vehicle next term, Winter 2004. Last Fall 2002 term's students designed the frame so that the final shell would make the vehicle look like the vehicle attached. We appreciate your help and the contributions that ZAP has made to our group. The UofM athletic department offered to let us parade the vehicle around the UofM stadium on game day next fall.

Thanks again for your help!

Braden Baldwin, UofMi
Jonathan Ho, UofMi
Adam Ouimet, UofMi
Ming Zhu, UofMi
David Swain, EPA