This is not a complete discussion of electrifying the bellcycle but mostly a product review of the AW Motor and Battery from Amazon.
36V Lithium ion Battery - AW 36V 14AH Li-Polymer Battery Water Bottle Type w Holder Charger For 36V 500W 800W Electric Bicycle https://www.amazon.com/gp/product/B00XP538DI
20 inch bicycle hub motor AW 16.5” Electric Bicycle Front Wheel Frame Kit For 20” 36V 750W 1.95”-2.5” Tire E-Bike https://www.amazon.com/gp/product/B01C6QZ2US
The battery kit includes a slightly noisy rear rack for mounting the battery. The rack was easy to install on the rear dropouts of the bellcycle. I just drilled and tapped two m5 holes into the dropouts and attached the upper mounts to one of the existing bolts on the rear pivot.
The motor kit includes all the wires you will need and they are already plugged in which is a nice time saver. The motor is heavy. I knew this but I forgot just how heavy. I mounted the motor controller under the rear battery rack.