Emergency Lighting

[macrouser 0]

Hello,

 

I want to make a cheap emergency lighting out of the stuff i already have here,

 

Ive got a spare UPS, Its designed to hold 2 loads e.g pc and monitor, How long would it last for if i was to place a normal lamp on it?

[Soundy 1]

That depends on the actual capacity of the UPS, and the wattage of the lamp (what wattage is "normal"?). Given those two numbers, you could calculate the time fairly easily.

 

Keep in mind that a UPS is designed to always supply its load when the power is on, and keep supplying it when the power goes out... emergency lights are typically designed to only go on when the power goes off. If you want this sort of functionality, you'd need to rig a relay circuit of some sort.

 

Actually, most of your readily-available emergency lights are 12VDC bulbs that run straight off a 12V lead-acid battery, very similar to the one that's inside your UPS. It's far more efficient, since you're not needing to convert the 12VDC back up to 120VAC, a fairly wasteful process in itself. A standard emergency light is very simple: a charging circuit that consists of a step-down transformer, rectifier, ripple filter and usually some form of current limiting; the battery; the lights; and a relay between the lights and the battery that stays open as long as AC power is supplied. Lose the AC feed, the relay closes, and powers the lights straight off the battery.