From NY -Times: While rechargeable batteries can be more economical than their disposable counterparts, they do have drawbacks. A new one usually requires a long period of initial charging before it can be used. Rechargeables are also notorious for their inability to hold a charge over time, even when sitting idle.
Various batteries (www.hybriousa.com) are ready to use right from the store and the company says that even after one year they will maintain 70 percent of their charge. Uniross estimates that once charged, Hybrios will run devices for up to four times longer than alkaline batteries. However, other brands are on selves at most menards (I bought them there ;-)
Hybrios, which the company says can be recharged up to 500 times, are available in packages of four AA- or AAA-size cells for $12. A kit with four AA batteries and a charger is $20, but any existing charger can do the job. RechargeablesOnline.com.