Awsum, I have 5 Spinners and 2 of them got warm the last time I charged them. I have two new chargers and have used one of them on all of the Spinners. Three of them charged without getting warm. I'll try charging one that got warm with the other new charger which I haven't used yet, just to rule out a charger problem. If it gets warm again then I'll know it's the battery. This is the first time I've ever had a battery get warm while charging and don't want to take the chance of using a battery that isn't safe. If they were both old batteries I would just dispose of them, but I just got one them the end of May. I thought I'd check it out before disposing of a new battery. I guess I could check with SI to see if that's covered under the warranty. Thanks for your help, Awsum. I appreciate it.