A:Answer My first set did the same, one of the connections wasn't touching the terminal on the charger all the way. I cleaned it real well and it started working again. You will have to reconnect it after changing. 2nd time it happened, i took it to my local electronic repair shop and they fixed it for $20. Not sure what all they did but it fixed it. They lasted 5 years before the battery on the left one wouldn't hold a charge anymore. Im on my 2nd set now, so far so good.