16:46 PM

Battery Pack Hack for a Bicycle Boost


Bored at home during the pandemic, people across the nation picked up new hobbies and purchased bicycles en masse. These newfound cycling enthusiasts in the City of Pittsburgh had to learn to adapt to some of the topographical obstacles around the city, including the miles of steep, rolling hills. Unsurprisingly, the popular city bike share — Healthy Ride — reported that stations at the top of hills empty out much quicker than the bottom of hills, prompting the introduction of electric-assist bicycles, or e-bikes. But what can new pandemic bike owners do to give those quads and lungs a rest?

A new 3D printed device from students at the University of Pittsburgh Swanson School of Engineering can provide a cheap, do-it-yourself solution for cyclists looking to add a boost to their bike.

“Our team created a system to power e-bikes using commercial off-the-shelf power tool batteries,” said Maya Roman, a mechanical engineering undergraduate at Pitt. “We designed 3D printed parts and simple wiring harnesses to securely mount two 40V RYOBI batteries to a bike to reliably power the 500W motor we installed. 

“By using commercial power tool batteries we hoped to employ the economies of scale that are soon to come for lithium-ion batteries, take advantage of the safety features already incorporated in the battery, and provide a battery solution for an e-bike that is easy to source and replace.”

The average e-bike costs more than $1,000, so tech-savvy hobbyists could potentially save a significant amount of money using batteries and other materials they have on hand.

You need slightly advanced knowledge about bikes to install the mid-drive motor we used, so you may need a bike-savvy friend to help you remove your bike’s bottom bracket,” Roman added. “Luckily our system will also power e-bikes with hub motors, which are easier to install.”

Users will also need access to a 3D printer and know how to use a soldering iron.

“To make our mount, you’ll have to 3D print the parts we designed and solder a couple wire harnesses that connect the battery contacts to the motor power input,” Roman explained. “You’ll have to install the internal harness to the mount, then bolt the mount to your bike. Then you just attach the wire cover, mate the connectors, slide the batteries into place and go for a ride!

This project is part of Pitt’s XProject program, a university effort to provide students with co-curricular design and engineering experiences that go beyond the classroom.

“We created the XProject program to give students a unique opportunity to solve design problems hands-on,” said Dan Yates (MechE ‘19), innovation project coordinator in the Swanson School. “Students get an immersive experience as they learn how to work through the design process, collaborate with teammates and clients, and apply the material they’ve learned in courses to a real-world project.”

Check out the following video to learn more about how the student team created their open source, DIY e-bike battery system.