Firstly thx for reply,not sure i understand ,reason i tested the battery was i just replaced the motor ,had a rod go thru side,so found a 12 hp same vintage and pulled my carb,flywheel,stator ect to keep everything the same.I cheaked battery to make sure everything was workin rite and chargeing,thats when i noticed the high voltage,really don,t want to ruin a perfectly good new battery and boil it dry or worse blow it up if thats possible.I always assumed u want the voltage to be somewere between 12.2 and 14.7.So replacing the Current Diode with a Zenner Diode will help? Please explain heat sink .Thx