After firmly re-securing the cables to their respective batteries, coat the battery posts and terminals with a light coating of grease to inhibit corrosion. If your vessel is not fitted with an on-board battery charger, your batteries will probably need to be charged using a portable charger. If you have a automatic battery charger aboard, check its output with a voltmeter at each battery bank. Your readings should be about 13.5 volts. Check your engine's alternator output too, by performing a similar test.
Batteries contain sulfuric acid.
Consider all areas on or around batteries to be contaminated with acid and take the necessary steps to protect eyes, skin and clothing. The failure of bilge pumps, float switches and related devices have caused problems this winter for some boat owners. Inspect the pump impeller area for debris or obstructions. Examine wiring terminals for corrosion and poor connections. Verify that the pumps do pump water.