I use AA and AAA rechargeable batteries, and I have developed a system that is dependable and effective for me.

My charger recommendation is Lacrosse BC-700:
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

My rechargeable battery recommendation is Eneloops:
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

The Lacrosse charger is a smart charger - it can charge any mix of AA and AAA batteries, you can change charge settings for each individual battery if you want, it will not overcharge (when battery is full, it switches to trickle charge to maintain). It is great. The Eneloops are durable batteries. I have been using the same 8 AAA's and 8 AA's for over a year, and they still hold a charge and function great.

My system:

I run two headlights (which use 2 AA's each) and two taillights (which use 2 AAA's each). So I have 4 AA's and 4 AAA's in use at any one time.

So I got 8 AA's and 8 AAA's and two Lacrosse chargers to run in a rotation. At any given time, 4 AA's and 4 AAA's are in the lights, and the other 4 + 4 are on the two chargers.

When I first started, I tried using just one charger, and trying to keep track of which batteries were which... but it was more complicated trying to keep charged batteries guaranteed that way. With my two charger method, I just keep the two chargers at my desk and swap battery sets every morning when I get in to the office. As the work computer is firing up and I'm getting my first shot of caffeine, I swap batteries and am done with it. 8 on the chargers, 8 in the lights, every day.

Whatever system you go with, definitely get some good lights. They are important. Good luck!