Honda GCV520 Owner's Manual page 7

The battery gives off explosive gases; keep sparks, flames and
cigarettes away. Provide adequate ventilation when charging
or using batteries in an enclosed space.
The battery contains sulfuric acid (electrolyte). Contact with
skin or eyes may cause severe burns. Wear protective clothing
and a face shield.
If electrolyte gets on your skin, flush with water.
If electrolyte gets in your eyes, flush with water for at least 15
minutes and call a physician immediately.
Electrolyte is poisonous.
If swallowed, drink large quantities of water or milk and
follow with milk of magnesia or vegetable oil and call a
physician immediately.
KEEP OUT OF REACH OF CHILDREN.
Use only distilled water in the battery. Tap water will shorten
the service life of the battery.
Filling the battery above the UPPER LEVEL line may cause the
electrolyte to overflow, resulting in corrosion to engine or
nearby parts. Immediately wash off any spilled electrolyte.
Be careful not to connect the battery in reverse polarity, as this
will short circuit the battery charging system and trip the circuit
breaker.
7