I have an N9 Ford Tractor. It has been converted to a12 volt with alternator. It has no spark recently. I found there was no voltage getting to the coil. Which was because there was no wire coming off the key ignition. It looked like someone pulled it off. There was also an old wire heading straight to the positive terminal that broke that was connected to the resister that connected to the wire that ran to the coil. So I connected the resister to the key ignition. It started up multiple times and ran. Then I went to replace the ignition switch cause it was not working. I have been doing screw driver starts for a while. After replacing it I put the terminals back on the battery but it sparks and sizzles. Why is the battery getting fried all of a sudden?