I have a utility building which houses my well water pump and the various water filters and treatments. It’s about 200 yards from my home. It is on it’s own power. I’ve thought of an emergency battery-backup power light system, but that doesn’t last long enough.- maybe 3-4 hours. If the power failed while I was gone, I would not know there was a problem if the battery had died. Other ideas that will light up when there is loss of power? Ideally a flashing LED to catch my attention. Of course there has to be a rechargeable battery to power the LED. I guess I could build something, but beyond my electronics knowledge how to use the absence of AC power to trigger the system to turn on and to turn off/recharge when power returns. TIA for ideas.