I am looking for an out of the box board / shield that can be used as a Li-Po UPS system for the photon / core. Essentially what I require is a board that implements ‘load sharing’ such that the Li-Po battery is not constantly charging / discharging when there is available USB power. Thus, when USB 5V power is available, the photon / core will be powered off that source and the UPS board would maintain the charge level of the Li-Po battery (without constant charge / discharge). When no USB power is available, the photon / core will be powered off the Li-Po battery. Ideally, the UPS board would also be able to signal the photon / core when USB power is lost / regained and when the Li-Po battery reaches low power levels / full charge.
The closest board that I can find is the Adafruit 390, but it is more than what I need (it is actually designed for solar power management) and is currently not in stock anywhere I can find.
Any tips about boards that are currently being used by the community would be greatly appreciated!