I mixed some baking soda into my favorite engine cleaner, Simple Green, for a fantastic battery tray cleaner. I give it two thumbs up!! And if Simple Green is too expensive, you can always get the Kirkland brand at Costco.

 

Strange...

I've got 7 year old stock batteries and never had to cleaner the batteries or the tray... A simple trick is to light coat all metal fastners, hardware and terminals with a light coat of engine oil and never have to worry again...

Have you ever noticed a oily/greasy part can never rust or corrode??

7 Years later...

 

yeah but this was on a duramax, they don't sweat horsepower like a cummins does!! it's all pretty, clean and quiet; and this one seems to overcharge the snot out of the batteries.

 

Ok... Then double check the wiring connections. Also like the Cummins there "should" be a battery temp sensor (Maybe) under the battery or similar to control the charge rate.