On 14/03/2011 09:39, Jonathan Hallameyer wrote: > On Sun, Mar 13, 2011 at 8:51 PM, Forrest W Christian = wrote: >> >> Michael Watterson wrote: >>> A rechargeable can self discharge in 2weeks to 16 weeks depending on >>> exact type. NiMH seem worse than NiCd >>> >>> Lithium Primary cells can last 10 years. >>> >> Although I agree - for the poster's purposes, non-rechargeables seem to >> be the way to go. And probably just good quality Alkaline is best >> because of the low current draw. I don't think Lithium gains you >> anything to speak of in this application - Alkalines seem better suited >> to low-discharge applications, and Lithium seems to do better in bursty >> high-current applications like cameras, although the exact nature of the >> application would probably have to be analyzed. >> >> -forrest The Camera type Primary Lithium batteries (non-rechargable) may not be=20 the same kind as used in Memory/Clock backups, not sure. They almost=20 certainly perform better in constant low current drain than in=20 intermittent high peak current applications though. AFAIK only NiCd especially likes bursty use as then nickel dendrites=20 don't grow? >> -- > Speaking of bursty... Lithium primary cells aren't anywhere near as > bursty, leakage wise, than alkaline. Which may be another reason to > use them in something you're going to let sit for a while. > Some PCs CMOS (originally clock power and the 64 bytes RAM in same chip)=20 used Alkaline batteries. Later they changed to large 2/3rd ish AA size=20 Primary Lithium Some early 286 used NiCd. These tended to go flat and also corrode=20 motherboard Now they all use a CR2032 or similar Primary Lithium coin cell. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .