While there is a lot of good info in this thread, I think that you may be confusing two different kinds of Lithium Primary cells. The ones which are targeted as replacements for Alkaline batteries are Lithium Iron Disulfide. They have better high-current discharge abilities and I believe that they are also lighter than Alkaline. New cells have an open-circuit voltage a little above 1.5V (Wiki says 1.8V). I do not think that they have better shelf life than Alkaline. The ones used for battery back-up for real-time clocks, etc., are Lithium Manganese Dioxide. They have a voltage of about 3V and have a shelf life several times longer than Alkaline. http://www.nexergy.com/lithium-manganese-dioxide.htm On Mon, Mar 14, 2011 at 7:15 AM, Forrest W Christian w= rote: > Michael Watterson wrote: >> The Camera type Primary Lithium =A0batteries (non-rechargable) may not b= e >> the same kind as used in Memory/Clock backups, not sure. They almost >> certainly perform better in constant low current drain than in >> intermittent high peak current applications though. >> > I meant in comparison to Alkaline - and in applications where a larger > (say AA-sized) battery would be in use. > > The 'rated' capacity of a Lithium AA and an Alkaline AA are nearly the > same - about 3000mAh. =A0However, the Alkaline can only provide that at > the low end of the current scale - say under 50mA of load. =A0 So, if > you're drawing under 50mA, and within normal temperature ranges, it > doesn't seem to make any fiscal sense to use Lithium over Alkaline, > considering Lithiums are easily 2x the price of an Alkaline. =A0 =A0 For > better comparison between the two, the datasheet at > http://data.energizer.com/PDFs/l91.pdf seems to do a really good job. > > You can also compare to the datasheet of an 'industrial' Alkaline at > http://data.energizer.com/PDFs/l91.pdf . =A0 Of particular interest are > the 'busty' voltage curves on this and the datasheet above. > > I will say that Lithiums are definitely more usable in a wider range of > temperatures and applications. =A0Personally, the 'Emergency Primary' > batteries I keep in the car are almost all Lithium cells. =A0For memory > backup, I'd use a lithium coin any day over about anything else - except > perhaps a supercap capacitor (1F or larger) if the amount of time for > backup was in line with what could be stored in the capacitor. > > -forrest > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .