Rechargeable is definitely an option. The only problem is alkaline batteries are 1.5v and rechargeable are 1.2 - 1.25v. Even with a good set of rechargeable, 5 volts is the best you can get.
If you want more info you can PM me.
Bill Wheeler - Cleveland TN
competition team member: Jack's Old South & Myron Mixon Smokers.com
Southern Q Model 500 Water Smoker
Jacks Old South Original Patio Smoker
Jambo - FEC100 - Bradley Smoker - Nfusion