When batteries are being charged, explosive gases are produced. Heat and sparks can ignite these gases causing a fire or explosion. All smoking, open flames, and spark producing items such as grinders, welders, or other electrical equipment, should be kept well clear of batteries. Surface leakage is a condition caused when dust mixes with spilled electrolyte on the battery, creating a low resistance path. This low resistance path can “short” the battery. Batteries should be kept clean and free of excess dust to protect against shorting.