I've carried a 9 volt battery on hiking/camping trips before, as an emergency fire starter with a bit of "fine" steel wool. And since duct tape is always handy in an emergency also, a short length of duct tape was halved and wrapped around the 9 volt battery in two directions, two or three wraps around the wide sides of the battery and up, over the top of the terminals to keep anything metal from touching them, and the rest of the length of duct tape was wrapped around the battery for storage. The steel wool was packaged and kept in a separate compartment. Never had problems with the battery shorting out on anything and never needed to use it in place of a Bic lighter or matches. The duct tape did come in handy a few times. I carry spare AA batteries for my headlight and a AAA battery for the tail light, but they're not a problem for shorting out in the repair bag.