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.
Ideas?