On Dec 14, 10:50, Sellam Ismail wrote: free for as is Any reasonable UPS will be heavy, because big batteries are heavy :-) Whether it's worth doing anything with it depends on whether you need a high-current or long-duration UPS. That one would allow you to boil the kettle for a cup of tea (or run the coffeemaker) during those power outages when there's nothing else you can do :-) It's not that hard to come by second-hand UPSs, the usual fault being that the batteries have gone bad (sulphated), and that's usually because people don't cycle them properly. There's some evidence to suggest that -- providing they've not gone too far -- high current high-frequency pulses can rejuvenate lead-acid batteries, and there are some circuits around designed to provide the remedy. I built one, and it seems to work, so long as the cells have *some* life left. Measure the voltage on each cell. If it's below 1V, or the cell looks at all swollen or distorted, it's past redemption. http://www.shaka.com/~kalepa/desulf.htm -- Pete Peter Turnbull Network Manager University of York