I've used rechargeable batteries in the past and had horrible results. They'd last about half a football game and be done. I'm now delving into other kinds of work and am using three 580EXII and a 320EX speedlight setup for portraits and other subjects. I recently did my first real portrait shoot using this lighting setup and noticed the Duracell AA's didn't last very long (shooting mainly manual at various power outputs). I've spoken with a couple of hobbyists such as myself and they've mentioned that rechargeable technology has made leaps and bounds so I'm looking into it but would appreciate any suggestions and/or experience you've had with these. OR, if there is another setup that lasts even longer, like a powerpack, I'd be interested in knowing your experience with those as well. Those can get expensive though. Thanks.