It's frequently smart to carry extra fully-charged model #18650 Rechargeable Batteries if you will be away from your "base" for a long period. This gives you a secure backup. Additional #18650 Lithium Ion Rechargeable Batteries for flashlights that use them can be purchased either singly or in packs of two. If your flashlight does not have an interior charging capability, the Intellicharger (04D05.10)
is an excellent accessory.