AA NiMH Charger
AA NiMH (nickel-metal hybrid cell) is a type of rechargeable battery of a penlight-size with two to three times the capacity AA NiCd. Like AA NiCd, NiHM batteries maintain relatively constant voltage when discharging but do not contain the toxic cadmium and do not have memory effect - loss of maximum energy capacity following repeated recharge after being only partially discharged what makes them ideal for digital cameras. The only disadvantage of NiMH batteries is higher self-discharge rate which can be as high as 5-10% on the first day stabilizing at 1% per day at room temperature although low self-discharge AA NiMH batteries are available as well since 2005.
To charge AA NiMH batteries you are highly recommended to use only AA NiMH battery chargers. Technically, AA NiMH batteries can be charged with some AA NiCd and alkaline battery chargers as well but they may result in overheating and overcharging as well as damaging of your NiMH batteries. AA NiMH battery charger can be bought together with batteries or separately. You can choose between different types of AA NiMH battery chargers (simple, smart, fast, universal and solar) from different manufacturers. Before purchasing both AA NiMH batteries and NiMH battery charger it may be helpful to inform yourself about the differences between AA NiMH battery chargers from different manufacturers and their quality although you will not find an unique answer to the question which one is the best. In first place choose an AA NiMH battery charger according to your needs and do not be guided by price alone.