Hilti lithium Ion Batteries

Hilti, I need your help with the use of Hilti B22 Lithium Ion Batteries. We were concerned about how to extend its life because some of our batteries are used regularly, while others are not even utilized in months. Some are charged almost daily, while others are not charged for long. Can you recommend a charging schedule for these batteries in order to get the most out of them? Is it OK to charge the battery and leave it uncharged for an extended period of time, or should we charge the battery right before use? Also Suggest the best practices for Lithium Ion Batteries Usage.