I would like a short-term backup power supply for an SBC4. It needn't last more than a minute or two. The idea is just to let the SBC send a notification of a power failure (detected on a Digital Input). Ideally, this would be a small Li-ion or Lipo battery and it would just float on the power supply/charger.
Also, extra points if the power-supply could be mounted on a DIN rail.
There are a bunch of devices that perform these kind of functions for RPi
They supply 5V
From that get a 5V to 9V DC-DC booster board and then power the SBC
the RPi UPS's are available and the DC-DC modules are available - then make a housing?
Other option would be to just use a stack of primary cells and a pair diodes as an OR
For example power the SBC from 15V
and then add a 12V Primary cell pack using something like the energizer lithium alkaline cells with 15 year shelf life
the lithium cells are unused until you need them.