Safety first: Designing an electric battery with street smarts
Kendall Bristow, Founder at FTN Motion, and Tim Hodgkinson, Lead Electronics Engineer at FTN Motion, share the story behind the Streetdog Classic’s electric battery.
"Safety has always been a major design focus for the battery," says Kendall Bristow, Founder at FTN Motion. The initial concept for the Streetdog Classic battery was initially designed by Bristow and Luke Sinclair, founders at FTN Motion, and then further developed by Lead Electronics Engineer Tim Hodgkinson. Here, Bristow and Hodgkinson explain the craftsmanship behind the battery powering the future of urban transport.
People waste hours every day commuting across town in gridlock traffic, pumping out endless clouds of emissions. This isn’t great for people or the planet, so Bristow and Sinclair set out to create a new commuter experience; one that brought back the fun and freedom to urban travel. They started tinkering with an old push bike in their garage, attempting to convert it into an electric motorbike with street smarts.
“The idea was to create a new breed of electric motorbike that complimented the urban lifestyle” says Bristow. “It had to be street smart, so easy to handle, fun to ride, nice to look at, convenient to charge, and safe to use around town.”
Thus, the Streetdog was born, along with an electric battery specifically engineered for urban commuting.
Safeguard against performance anomalies
Battery Management System (BMS): Designing a BMS to ensure the safe usage and longevity of the Streetdog’s electric battery was crucial, as Hodgkinson explains: “Our approach involved developing software to monitor battery and motor performance, including voltage, temperature, and electric current. We use multiple sensors placed at various locations in the battery to track performance. The BMS continuously monitors the discharge/charge current as well as cell group voltages and pack voltage. If performance reaches a concerning level the BMS initiates a series of protection protocols, activating switches to disconnect the battery and ensure safety.”
“The components that act as switches include a contactor, transistors and fuse. A signal from the bike controller tells the BMS to close the contactor, which supplies power to the motor. Transistors switch the electric load on and off under fault conditions, and the fuse acts as a last resort to fully disconnect the battery if needed. The contactor also allows the battery terminals to be fully disconnected when not in use, preventing the user from potential shocks. This three stage protection process makes the battery a lot safer than most other batteries.”
Battery cells built to last
LG 21700 Li-Ion Battery: Ensuring battery components are fault-free is another critical safety aspect, particularly in the cells where the electrochemical reactions occur to generate energy.
“We have partnered with LG Energy Solution in South Korea,” says Bristow. “LG is renowned for its battery cell technology, with their cells used widely across the automotive industry, from Tesla’s range to Porsche new electric Taycan.”
Protected from wild weather
“Protecting the battery from environmental factors is another key safety consideration,” says Hodgkinson. “We use a die-cast aluminium casing to achieve an IP68 waterproof rating and dust protection. This casing also acts as protection against knocks or drops.”
Charge and go
“A battery wouldn’t be street smart if it weren’t removable” adds Hodkingson. “This feature allows you to charge it at home, at work, or from any standard power outlet, alleviating range anxiety. It also means you can easily switch batteries, effectively doubling your range. A second battery fits into the 30-litre storage compartment. At just 15 kg, the battery is also relatively lightweight, making it easy to remove and replace on a daily basis.”
Maximising battery performance and safety remains a key design focus as the R&D team at FTN Motion designs the next generation of urban motorbikes, or as we like to call them, Streetdogs.
To upgrade your commute or explore around town, the Streetdog is the electric motorbike bringing fun and freedom back to urban travel. Crafted in limited runs in New Zealand, you can reserve yours today and take one for a test ride.
