I’m trying to understand the correct way to add a secondary “long term” battery to a CubeCell (AB01) for a standalone LoRa sensor (target is 1y to 2y continuos working time)
one of the sensors I’m using has a high drain current (2mA) and that is a hard limit I cannot change.
On CubeCell we can user solar+lipo battery and have a decent working time, but how can I add a secondary battery (i.e. an external lithium/alkaline + regulator) that will take over when the lipo battery is empty (for example in winter time?)
right now I’m using a voltage detector directly on the lipo battery and when I sense ~3.3v I enable the voltage regulator on the external battery which is connected to V3.3 on the CubeCell pin.
but I’m worried this is not the best way of doing an UPS for CubeCell because I suspect there could be a situation where the onboard CubeCell regulator is still pumping some power.
Is there a better place/pin where to sense for power input and trigger an external power supply?