White, green, or blue crust on a golf cart battery post is corrosion from acid vapor. It raises resistance, so the cart feels weak even when the batteries still have charge, and it makes the charger work harder.
Clean the posts
Turn the key off and disconnect the main negative cable first. Mix a paste of baking soda and water and brush it onto the crust. It will fizz as it neutralizes the acid. Scrub the post and the cable lug with a terminal brush, rinse with a little water, and dry everything. Do this outside or in a wash bay, not over a finished floor.
Put it back tighter than you found it
The lug has to sit flat on clean lead. A rocking cable will arc and pit the post. Coat the post with a thin film of dielectric grease or a terminal protectant after it is tight. Replace any cable whose strands are green inside the insulation or whose lug is eaten through. A new battery on a rotten cable will not fix the cart.
If the hold-downs are loose, the batteries bounce and crack the posts. Tighten them before you close the seat. When you are ready to replace the pack, match the terminal style (S, UT, UTL, or marine) so the cables you just cleaned still fit. See the fitment guide.
