I'm gettin a green corrosion buildup on my 401 bat. Had the bat about 2 weeks. It occurs on the thread connection end on the ring insulator between + and - connectors. It resembles the corrosion on car bat terminals. Have 4 bats and all are getting it. I soak the connector end in baking soda+water solution for a min and helps but comes back in a few days. Anybody having the same problem? 