Have a Cordless Tool Battery Won't Recharge? You Can Fix That.
Ryobi P117 One+ 18 Volt Dual Chemistry IntelliPort Lithium Ion and NiCad Battery Charger (Battery Not Included, Charger Only) - Power Drill Accessories - Amazon.com
DIY Fix for a Ryobi 18v Battery That Won't Charge – Home Battery Bank
How to Fix a Ryobi Battery that Won't Charge - Easy - Not Sealed