An employee was watering a lift battery (approximately 350 lbs.). The battery did not have the retainer in place at the time. As he was pulling on the lid of the battery, it rolled out of the compartment and fell over. He tried to catch it and it fell on his right hand, smashing fingers two - five. Sulfuric acid also leaked from the battery onto his hand. His right long finger had to be amputated at the second knuckle.