It can be wise to use rechargeable batteries for your guitar pedals, both as a cost-saving measure and as a matter of convenience. Though rechargeable batteries are more expensive than their non-rechargeable counterparts, they'll last considerably longer through multiple charges. Energizer says its rechargeable batteries can withstand "hundreds of charges." The number of charges varies based on the draining power of the device in which they're used, and Energizer says its batteries must be charged at least every six months for optimal life. Additionally, you won't have to spend as much time going to the store to buy replacement batteries.
According to the website Green Batteries, the common belief that disposable batteries last longer in electronic devices than rechargeable batteries is largely a myth. Green Batteries says that in many electronics, rechargeable batteries will provide power for a longer duration. As such, it's useful to use rechargeable batteries in guitar pedals.
If you choose to use rechargeable batteries in your guitar pedal, read the information on the package to learn about the charging process. Typically, the package will explain how many charges the battery will withstand. Rechargeable batteries also last longer when they're charged from empty, rather than charged when they still work. In this case, it's wise to leave your guitar pedals on until the batteries are dead and then recharge them prior to your show.
Many guitar pedals give you the option of using batteries or an AC current. If you're concerned about battery life and are playing in an area that has easy access to wall jacks, consider using the pedals' AC jack as an alternative to batteries. This way, you'll have power to your pedals without having to consider the life of the batteries.