I am outside USA. I got a Tennis Tutor 2 months ago. I charged it about 10 times. Now the battery is almost dead. I verified the charger and it works, but the eletric tension in my city is 127V and the output shows 18 VDC (not 12 VDC). I donīt know this 18VDC can reduce or kill the battery. Could anyone help me what to do?
