A 20v XR Lithium Ion 4.0A battery on my DeWalt reciprocating saw while fully charged has begun stopping and restarting while under load. If I pull it free it will run strongly. I changed batteries and the saw works fine. Battery is about 3 years old. I have worked it pretty hard cutting 3" holly trees down over its life. Is this a typical lifetime for that battery? Will a 5.0A battery last any longer?