ATOMO:  The Electric Bike Project

ITEM Details Cost (USD) Image
A Bike I Craigslisted a bike, 25 dollars. Took 2 weeks to find a cheap bike, but it was worth the wait
(not a pic of the actual bike but rather close)
The Batteries This is key, batteries are the achilllies heel of any project. I managed to get NiZn recycled forklift batteries via a friend (john you rock). Yea, NiZn, i had no idea they existed in this format either.  Check your local recycling center, or just ask around Craigslist.  I scavenged somewhere near 36V at 30AH of power. total mass is less than 40lbs. 36
The Motor Defunct Alternator. defunct from lack of brushes for field winding, then again, i didnt really mind, as i wasn't planning on using them. free
Controller Homebrew 12 Images and Schematics Will be posted pending further tests.
Gearing and Chain Mcmaster
(#50 chain + 9 tooth sproket)
Sprocket:  link
Chain: link
Battery Charger Homebrew. 38V, 10/15A. 2-3 hr charge time.  24 Images and Schematics Will be posted pending further tests.

The design of the cycle is, well kinda ridiculous. Quite a number of modifications were necessary to achieve the necessary structural stability and handing for proper operation. As shown below, the cycle operates in 3 distinct states, Human, Electric, and Hybrid mode. To achieve this, two rear (free-wheeling) tires and hub assembles were used. the second tire was scavenged off of cambridge's re-use system. FEA was used on the front end to determine if aluminum braces were sufficient
In case 1, its a normal bike with a lot of extra mass, the motor and drive train for the electric side are completley isolated from each other, and pedaling isnt loaded by the motor, it actually doesnt move the chain at all (thus the 2 free wheels). In case 2, the system is a purely electric bike, it has a fixed gear ratio, and is front wheel drive, when the motor is over driven (bike is going faster than motor, like in a long down hill, the motor isnt forced by the wheel, its in a freewheel state. also the pedals arent forced to spin up when the motor is on, they are also in a free wheel state In case 3, the system is a parallel hybrid, wherein rear wheel propulsion is provided by the human, and front wheel propulsion is provided by a motor. This instance would happen when the cycle is started up from a complete stop, like after a red light.

Rensselaer Polytechnic Institute 
Electrical & Electrical Power

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