I have a few suggestions to see if I can help you, charging the battery first to look at the number of charging, you see how many times you can charge and discharge, the more sure the better, and then if it is not commonly used, you can also look at the \"Duracell\" brand of batteries, because we usually do activities are used this, the power can also be (declaration: I am not advertising!) If you keep singing, you can do it for at least six hours straight. That's my advice.