How will I know if my battery is fully charged? March 15, 2018 14:03 Updated Follow When you are charging the racket, the red light turns to green when the battery is fully charged. Related articles What is 100% of power for the forehands and the backhands? Will my racket warn me if the battery is low? How long does it take to fully charge my battery? Comments 0 comments Article is closed for comments.