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For anyone who still has devices with old AA, AAA, C, D, or 9V type batteries in it I highly recommend you move over to the USB chargable Li-ion type of the same format.
Most of those devices dont work with traditional rechargable batteries like NiMH because the voltage is a bit lower. Even if they do work they tend to last only a short period of time because as they discharge the voltage drops even further. So your device will often die even with 70% of charge still in those batteries.
With the newer USB rechargeable Li-ion type batteries of the same form factor, however, you have a drop-in replacement that doesnt have those issues. They basically are a LI-ion battery with a built in charger but more importantly with a DC-Dc converter to keep the voltage fixed at the desired voltage (1.5V or 9V) for the entire life of the battery. So they work in any device that they can fit in and lasts a long time as they deliver 100% of their power before cutting out (at which point it drops from 1.5V directly to about 0V).
The only downside is if your device reports a battery percentage then it will report 100% battery right up until it hits 0.
Anyway I replaced all my devices with batteries like this and they last longer than regular batteries in some cases (especially with 9V)... so I am sold!
This is Mur 
@freemo
But how will I extract graphite then?
@mur2501 Use pencils, it wont be caked in chemicals that way either. The easiest way I found to get them out of pencils is to expose the graphite on both ends then hook a voltage onto it. Crank it up until the pencil starts smoking, leave it like that for a minute or two, turn it off, let it cool down then the graphite will slide right out.
@freemo
Indian consumers don't really plan much when it comes to this things, as batteries would only be used in wall clock and remote controllers so they would just go with the cheapest option. Actually a peculiarity of Indians is that we will invest more in stuffs which will showoff our wealth to others rather then tye stuffs which increases efficiency, reliability or quality of life. This is the main reason why Indian weddings are so lavish and costly.
@mur2501 Fair, I certainly cant speak for the average consumer. Only to what is a "smart" buy in this case.
@mur2501 I'm not so sure.. most people have very few devices that need them.. 20$ - 60$ will likely cover all your devices. I'd say thats more than worth it since it means you never buy another battery again, your devices last forever, and now you've made them rechargable.