Honda EU3000is Owner's Manual page 60

SERVICING YOUR GENERATOR
Battery Charging
The battery is rated at 8.6 Ah (ampere-hours). Charging current should
equal 10% of the battery's ampere-hour rating. A battery charger
should be used that can be adjusted to deliver 0.9 amps.
1.Connect the battery charger following the manufacturer's
instructions.
2.Charge the battery 3—4 hours.
3.Clean the outside of the battery and the battery tray compartment
with a solution of baking soda and water.
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The battery will expel explosive
hydrogen gas when overcharged.
A spark or flame can cause the
battery to explode with enough
force to kill or seriously hurt you.
Always use a regulated charger that
provides the correct charging
current to prevent overcharging.
Wear protective clothing and a face
shield, or have a skilled mechanic
perform the battery maintenance.