Saving any type of RYOBI drill battery requires properly maintaining, using and storing the battery in an appropriate location when not in use. This will notably extend the life of any battery, including the 18 volt Ryobi batteries generally used in conjunction with Ryobi cordless power tools. Failing to fully charge your batteries before use, overcharging, or storing your batteries for a prolonged period fully charged will all shorten a battery's life.
Insert the 18 volt Ryobi battery firmly into its associated charger when you are ready to use it. Plug the charger into an electrical outlet and let the battery charge for at least one hour.
Take the battery out of its charger only when it is fully charged. The indicator light on the charger will turn from red to green once the battery is ready (depending upon the model). Partially charging BPP-1815 batteries before use on a repeated basis will shorten the battery life.
Operate your Ryobi power tools on lower power settings when possible so as not to drain all of the battery's power.
Turn off the Ryobi cordless power tool you are using as soon as you have finished your job in to further preserve the battery.
Remove the 18 volt Ryobi battery from its associated power tool when you wish to store it. Place the battery in a location where it will be out of direct sunlight and where it will be stored at a temperature below 80 degrees Fahrenheit. Storing at the correct temperature will help save the Ryobi RB18L40 battery.