I increased the size of the case to accommodate a cheap step-up regulator meaning the pack always puts out a pre-defined voltage (I set it to 8.4v).
Servo plug is for charging as my charger requires the discharge as well as balance lead connected. Do not plug the main discharge lead in to a charger as this is connected to the step-up regulator output.
DC Boost Converter: https://www.banggood.com/5X-DC-Boost-Converter-2A-Power-Supply-Module-2V-24V-To-5V-28V-Adjustable-Regulator-Board-p-1181876.html?p=DU271811622582015018
LED indicator board (2S version): https://www.banggood.com/1-5S-Lipo-Battery-Voltage-Display-Indicator-Board-p-1073721.html?p=DU271811622582015018
5.5x2.1 right angle DC jack: https://www.banggood.com/DC-Tip-Power-Plug-Jack-Connector-Dual-5_5-x-2_1mm-Male-Right-Angle-Cord-Cable-p-1161332.html?p=DU271811622582015018
Also requires 4x 20mm M3 bolts, 2s balance lead, standard servo lead, hot glue!
UPDATE:
If you buy the cheap DC boost converters be sure to buy a multipack. The first one I used blew about 10 minutes after assembling. The boost regulator IC burned up. Replaced the module and so far the second has been fine so perhaps just bad luck with the first module.
| 18650_case_bottom.stl | 66.2KB | |
| 18650_case_top.stl | 68.2KB |
