Mercury Electric Outboards 222 Thruster Service Manual, Page 9Get this manual
may form an explosive atmosphere around battery if ventilation is poorThis explosive gas may remain in or around battery for several hours after it has been chargedSparks or flames can ignite this gas and cause an internal explosion which may shatter the batteryThe following precautions should be observed to prevent an explosion 1DO NOT smoke near batteries being charged or which have been charged very recently2DO NOT break live circuits at terminals of batteries because spark usually occurs at the point where live circuit is brokenAlways be careful when connecting or disconnecting cable clamps on chargersPoor connections are common cause of electrical arcs which cause explosIOns3DO NOT reverse polarity of battery terminal to cable connections, as components can be severely damaged ACAUTION
If battery acid comes Into contact with skin or eyes, wash skin Immediately with mild soapFlush eyes with water Immediately and see doctor