Camping On weekend

My friends and I are planning to have a camping this weekend. This has been planned a month ago in fact it has rescheduled for the third time. I will be bringing a lot of food so we can all have fun. At the same time I think I should also bring some basic tools and blanket just to keep ourselves safe. I will list down all the things needed  but hey I forgot to ask, where can I buy power tool batteries? Maybe I should go and check in the nearby store.