While most e-bike manufacturers focus on maximizing range with ever-larger battery packs, content creator Seth from Berm Peak took the opposite approach, engineering what may be one of the smallest functional e-bike batteries possible.
The “Bermacell” pack utilizes just 14 Samsung 18650 cells arranged in series, each rated at 3000mAh, delivering a total capacity of 156Wh at 52V. The minimalist design prioritizes portability over endurance, targeting riders who need just enough power for short recreational rides rather than long-distance touring.
Seth’s construction approach was refreshingly straightforward: spot welding the cells in series configuration with an off-the-shelf battery management system, then housing the entire assembly in an oversized 3D-printed case styled after a classic 9V battery. The playful form factor belies the pack’s serious engineering underneath.
Real-World Performance Testing
To validate the Bermacell’s capabilities, Seth integrated it with a Bimotal e-bike conversion system on his trail bike for testing at Kanuga bike park. The compact pack delivered three full laps with approximately 1,500 feet of total elevation gain—impressive performance considering its minimal capacity. Seth believes a fourth lap would be achievable with more conservative throttle management.
For urban riders, a separate test involving a 13-mile round trip to a local coffee shop demonstrated the pack’s viability for short commutes when combined with pedal assistance.
Future Iterations
Seth plans to push the compact design even further with a sub-100Wh version specifically designed for air travel compliance, opening up new possibilities for cyclists who want to bring e-bike capability on flights without shipping restrictions.
This project continues Seth’s track record of innovative e-bike modifications, including his previous work reverse-engineering pay-to-ride e-bike systems.
Watch the video here:
