From: Alexandre P. N. <al...@om...> - 2006-09-08 16:11:13
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Alec Waters escreveu: >Hi Brad, > > > >>I wrote that and I might also be out of my depth, but nimh aa batteries >>are 1.2v so I figured four was a better setup. >> >> > >D'oh! 1.2v, not 1.5v. Makes sense now :) > > 1.2v x 3 = 3.6v, which works but the bare minimum for gumstix is 3,4v, since nimh drops voltage fast as it discharges (as opposed as li-ion, at least), that means gumstix would shutdown when batteries still had a long way to discharge. 1.2v x 4 = 4.8v , which wastes a little extra power as heat (because of the voltage regulators), but will probably allow you to go all the way down the discharge cycle of the batteries. >>ah yes I meant to get back with the supercap specs. I'm actually not >>sure about nimh. they don't have the high internal resistance that makes >>the supercap good for alkaline. >> >> > >OK. > >thanks very much, >alec > > I remember reading some posts a long ago about that, I think I asked the same question myself, it seems like he is correct, the alkaline batts suffers if the load switches too much (the processor runs based on clocking, every clock cycle it does some work and that requires power, it idles between cycles and apparently this kind of battery doesn't appreciate that. It seems that nimh does fine). - Alexandre |