How should I maintain the battery pack to maximize its lifespan?

Store and charge batteries in a cool area, as temperatures above or below normal room temperature will shorten battery life. Never store batteries in a discharged condition — recharge them immediately after they are discharged. If storing the tool for long periods without use, recharge the batteries every month or two to prolong battery life. Do not disassemble the battery pack or attempt to replace individual cells. (Page 15)