I have five cars all with 12 volts and electronic ignition but only one has had a problem for the past five years. I have replaced all wires and battery but every six months I will find the car hard to start. If I check the battery "post" cranking voltage it is near 12 volts, but if I check the lead battery post "clamp" it will show 8 or 9 volts. Take the clamp off the post and I find a very light white haze. Wire brush off the haze and all is well again for another six months. I have tried grease to prevent it along with pennies etc. Nothing I do seems to stop it from happening. The car can sit for months and crank well the battery never seems to be drained by this problem. Any ideas
Larry
Larry