Its a useful idea if you already have the LiFePO4 cells lying about, but otherwise I tend to agree with reyalp. the capacity of the battery is the important factor, and these small 104500 LiFePO4 cells are typically around the 600mAh mark, some as low as 200mAh (although the actual capacity of a lot of no-name brands on the internet is often massively overstated, I bought some AAA NiMh recently that claimed a massive 1800mAh I suspect they are the same as the 800mAh ones, they were after all the same price, so I was under no illusion about their likely pedigree).
The increased voltage (3.2V vs. 2.4V for two NiMh AA batteries) shouldn't be a factor in a camera which is designed specifically to use NiMh, (older cameras which are designed for Alkaline cells might care, but probably not, they would either work fine for most of the full capacity of the NiMh cells, as their discharge curve is generally fairly flat, or simply fail to work at all). In this case you would have to do the experiment... 2 x quality fully charged 2000mAh AA NiMh cells versus 1x 600mAh 104500 LiFePO4, my money is on the NiMh cells with the higher capacity.
If you want to use LiFePO4 batteries, you would be better using them through the external power adapter jack, then you can get some serious capacity batteries. For example something like these...
http://www.hipowergroup.com/products/LiFePO4%20batteries/ 3v2 at 50 Ah that should keep your powershot buzzing for quite a while (someone do the maths for me please) The $100 price tag might put you off though (not including charger
)... However if you just want an alternative power source to replace the AA batteries in your point and shoot, you might be better to spend your $20 on a bunch of conventional AA NiMh re-chargables (typical capacity for a good named brand is around the 2000 mAh mark, Energiser do a 2450 mAh variety, they claim is good for 325 shots, not sure how they work that out... ), and just try to remember to charge them up, that way you will get more than 10 shots out of them next time you turn the camera on
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A side note, the poster of the article may have fixed his problem for an entirely different reason. Canon cameras tend to have an issue with the springs that hold the batteries in place, as has been discussed elsewhere on this forum, as I recall. The reason he may be having more success with the 104500 is that they are sometimes a fraction longer than your average AA cell, and it, or his wooden dummy cell, might simply be making better contact with the non springy springs in his SX110.
