Slendertone Optimum switches off during a toning session? Recharge the batteries for 3 hours, once charged start your toning session again. If the problem persists please contact us. Related articles What happens if I connect the coloured leads incorrectly? The controller does not switch on when the Power button is pressed How long does the battery take to charge? Optimum Instruction Manual The Connect controller keeps beeping Comments 0 comments Please sign in to leave a comment.