Ryobi One - BPL1815 Double-up battery case

thingiverse

Warning: Do not attempt to modify or service the battery if you are unsure of what you are doing. Avoid asking about building or modifying batteries; do this at your own risk. My BPL-1815 battery was showing signs of age and needed a rebuild. I decided to replace it with double the number of cells, but only had space for 5 cells. So, I designed this replacement bottom part for the battery case, which fits about 95% of the original BPL-1815 battery and probably most Ryobi One+ batteries. I used the original top plate, BMS, screws, and buttons. When using the original BMS, there's the benefit of using OEM chargers (as long as the BMS is okay). Keep in mind that the BMS in the BPL-1815 batteries have MOSFETs that max out at around 20A current, so use this information when choosing battery cells. I chose Sony VTC5A cells, which are overkill for this application. Something with 10-15A and 2500-3000mAh would be suitable for this modification. I reshaped the button springs to fit the new case height. Use an old solder iron to melt filament in the spring holes and on top to keep the springs in place and provide some insulation, preventing shorts between cells. I couldn't use the rubber piece in the bottom; the design is a bit too small. I ended up not using it since I felt the battery cells were firmly in place without it. The fit is about 95% or so. It goes together with some mild to medium force. Mine is built, and I have no more batteries to service at the moment, so I probably won't make any adjustments.