The short answer is: Those coin cells aren't meant to source 25mA constant current. An occasional spike of current is fine; constant current ruins the battery and you get a much worse lifetime. Notice that the battery is rated, in your case, for 0.2mA load! If you look at the graph at the bottom of the datasheet, the capacity drops off exponentially with increased continuous load:
http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_Lithium_CR2330_CR2354.pdf Lithium coin cell batteries drain without affecting voltage, and then fall of a cliff when their life is over. The Panasonic 2354 is a fairly bad choice for wireless sensor networks with a duty cycle larger than about 0.5% (avg system current consumption of 100uA). -Joe Keep in mind that the capacity of the battery, rated in mAh is at a particular discharge rate. In your case On 12/7/05, Amanda Williams <[EMAIL PROTECTED]> wrote: > Does anyone have any idea what might cause xbow mica2dot motes to devour > batteries? I checked the data sheet for the motes and the batteries > (panasonic 2354s... the ones they came with). The batteries ought to > have about 560 mAh, the mica2dots suck 25 mA while the radio is sending, > and the led draws another 5mA.... even drawing the maximum amount of > power all the time, I'd expect the battery to last close to 18 hours... > mine died in 7. > > And, testing these guys out now, they're not really using the radio > *that* much. twice a second max, and they are going for long periods > without receiving or sending over radio at all. > > thanks, > amanda > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
