Mobile power station for storing some juice to power our phones and other devices on the trail! We created our own battery modules with 138.24Wh of capacity, made from 8 21700 cells. 28.8V so we can use simple step down converter to get constant 24V, we don't need to use step up step down converter full bms with cell balancing and overvoltage, undervoltage and overcurrent protection 10A fuse of last hope, if other safety measures would fail!