John R Pierce wrote: > On 07/01/11 4:05 AM, Timothy Murphy wrote: >> It seems to me that it should be possible >> to have a simple, torch-battery operated > > assuming 'torch' in this context means what us yank's call a flashlight, > and that a 'torch battery' is a C or D cell, lets see how much juice we > could get out of a reasonable setup.. > > According to HP's 'quick specs', the Microserver has a 150W supply, that > nominally draws 0.63 A (from 115VAC) or 0.35 A rom 220VAC, about 75 watts. In fact, my MicroServer has never exceeded 45 watts, and usually runs at about 30 watts. I'm not sure what sort of current a computer uses when shutting down? > According to wikipedia, an alkaline D cell is typically rated at 1.2 amp > hours at 1.5 volts. Most inexpensive AC inverters run on 12V > (automobile power), so we'd need 8 of them to get 1.2AH at 12V or about > 14 watt*hours... My calculations seem to suggest you'd get maybe 9 > minutes total from those 8 batteries with an 80% efficient AC inverter > at 75 watts. And then of course, you'd be throwing those 8 D cells > away and replacing them with new ones. Actually, I would only want the batteries to last long enough to shut down the computer cleanly, which I think takes about 30 seconds. And we can get quite large 12 volt batteries pretty cheaply this side of the pond. Nb I didn't say, or mean to say, that I wanted to _make_ a "flashlight UPS". My electronic skill is close to zero. I was simply expressing surprise that no-one had done it. I've been completely convinced that a UPS is what I need, and am trying to source the APC UPS-BE350G, which was recommended. -- Timothy Murphy e-mail: gayleard /at/ eircom.net tel: +353-86-2336090, +353-1-2842366 s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland