After buying my first Onewheel, a Onewheel Pint in 2022, I slowly learned that I wanted more range. The Onewheel Pint delivers plenty of torque but has a limited range of 7 miles. Onewheels with larger range, Onewheel XR and GT, cost over $2000. To create a cheaper long-range board, I decided I wanted to purchase a used Onewheel Plus due to its low cost, larger size, and most importantly, ability to be easily modified.
I found a Onewheel Plus on Facebook Marketplace for $550 that included an extra external battery. Since it had an external battery, I had no doubt that its power source could be modified. I needed a Onewheel that would operate as long as the controller received the correct voltage but did not require any communication between motor controller and BMS. The Onewheel Plus is only the second board made by Future Motion and thus did not require any communication between these two devices.
Soon after buying this board, as any engineer might do, I took it apart. The seller told me that the main battery in the board was not working and he had added an extra external battery. So the Onewheel did work when I bought it, but only with the external battery. The seller had supplied an additional Onewheel battery to replace the current one. This was why I took it apart.
After swapping the batteries, I found that the battery was not the cause of the need for the external battery. After another deconstruction and some research, I found that the BMS was probably the cause of my problem. This led me to a more immediate battery build.
To build a cheap, performant battery, I sourced some INR21700M50LT cells from Battery Hookup for about $1.70 per cell. These are 5000 mAh 14.4A max discharge cells. My goal was to build a 14s3p pack allowing for a max current of 43.2A. I purchased a 100A smart Bluetooth BMS to manage the pack. This pack was 756Wh or 15Ah up from the stock 2.6Ah.
Unfortunately, this pack could not fit inside the normal battery compartment even with my custom 3D printed Battery box and aftermarket rear bumper from The Float Life. To accommodate this large pack, I placed the BMS on top of the box and made the foot pad go over it, making the rear foot pad higher than the front.
This pack came to a halt when one cell hit its bottom voltage of 2.5V when the rest were still around 3.7V. At its worst, along with some bad BMS configurations, this caused the board to give out long before it should have, while moving 20mph.
I later built a 14s2p pack with P42A cells which are 4200mAh and 45A Max discharge. I also used two different BMS's and redesigned my battery box to accomdate the battery and the BMS along with a stronger over all design. More Information on this design coming soon...