Try refreshing your Li - ion battery before trashing it. What have you got to lose?
This describes how to refresh a Sony NP-FM50, 7.2v, 1180maH battery that seems to be used in many digital cameras, camcorders, and cell phones. Higher capacities, e.g. 1500maH, 1800maH, simply take longer to discharge. If the voltage happens to be different, just match the bulb referenced below to the voltage.
Li -Ion batteries work on passivation(a chemical layer that forms on the anode/cathode to prevent charge flow) of the "plates" that enable it to maintain its charge. If you haven't used the battery for awhile, completely discharge it using a 10ohm, 10watt resistor, and a 7v bulb in series. Recharge a couple of times, and it will probably start working normally again. Dont waste your money and resources by trashing a battery with life in it.
You should be able to get the resistor and bulb from stores like Radio Shack and Fry's. I discharged mine using 3 jumpers with alligator clips, a clothes pin, and piece of flashing. Just get the bulb lit up and go away until it goes out; very dim might be better if you're a stickler.
If you research this subject, you will find that complete discharges will ultimately reduce the overall capacity of the battery by a small amount. That is to be expected. Do you care as long as it works?