1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 33Get this manual
BATTERY Precautions When charging balleriesan ex plosive gas mix ture form in each cellPari of this gas escapes thru hol es in vent plugs and ma for an e: plos ive atmosphere around battery if ventilation is poorT hi explosive gas may remain in or around balte ry for several hours after it has been chargedSpar ks or names can ignite th is gas and cali se an internal xpl osion wh ich may sha ll er the halleryThe following precautions shoull] be observed to prevent an explosionJDO NOT smoke near batte ries being charged or wh ich have been charged very recently2DO NOT break live ci rcui ts 011 terminals of ballcrics because spark usually occurs at the poin where live circuit is broken Always be ca reful when con necting or disco nnecti ng cable clamps on chargersPoor connectio ns are common cause of electrical arcs which cause e1( plosions3DO NOT reverse polarity of battery lerminalto cable connections
ACAUTION
If battery acid comes Into contact with skin or eyes, wash skin Immediately with mild soapFlush eyes with water Immediately and see doctor