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.