Get a charger for the old rechargeable pendant if your pendant is on a wire this is what you need to charge it. Sadly, if you are looking for a battery for this version I don't have anymore, and will not be getting more since I have now upgraded to the new usbc type pendant. Please email Lucas@aglowgeo.com if you have lost the old battery and want to upgrade from this old version to the new improved usbc rechargeable pendant and we could work something out!