Batteries generate explosive gases during vehicle operation and also when charged separately. Flames, sparks, burning cigarettes or other inflammable sources that may start a fire must be kept away at all times.
Always shield eyes when working with batteries, as sparks, acid splurge etc. may hurt the eyes.
When charging batteries, work in a well-ventilated area - never in closed spaces.
Always turn battery charger or ignition off before disconnecting a battery.