I use 2600mAh rechargeable batteries, and I have had them last for 1 month without them dieing. However, I have 4 controllers and all of them had batteries in them, and they are all really close to dead now, so I need to recharge them.
The fastest I've ever had to replace the batteries is ~1 week.
This is the charger I have, and it works great.
http://www.batteryjunction.com/ch10chsmchwi1.html








