On Fri, 4 Jul 2008 22:47:30 -0700 "William \"Chops\" Westfield" wrote: > > >> would it not be best to make a statement such as "This battery > >> has 760 milliwatt hours and has an internal resistance of 5 ohms", > > No, it doesn't work that way. if it was only an internal resistance, > it wouldn't affect capacity, only maximum current draw. The > reduction in capacity is due to chemical effects (in ability to > recombine chemical byproducts of the electricity-producing reactions > at the full rate of production, for example) that aren't easily > modeled by purely electrical characteristics. > > BillW Exactly... Check, just as an example (no endorsement): http://www.pilasduracell.com.ar/oem/Pdf/new/MN2400_US_CT.pdf On the first page, it shows the discharge with several different loads, but the graph you're interested in, is on the second page, "Typical discharge performance". At 50 mA, the mA capacity doesn't even reach 1.2Ah (1200 mAh). DC internal resistance increases with discharge, as with all batteries, and just determines terminal voltage. John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist