Honda EU20i Owner's Manual page 38

DC application
The DC receptacle may be used for charging 12 volt automotive-type
batteries only.
NOTE:
In DC operation, turn the Eco Throttle switch to the OFF position.
1.Connect the charging cable to the DC receptacle of the generator and
then to the battery terminals.
• To prevent the possibility of creating a spark near the battery,
connect charging cable first to the generator, then to the battery.
Disconnect cable first at the battery.
• Before connecting charging cable to a battery that is installed in a
vehicle, disconnect the vehicle's battery cable. Reconnect the
vehicle's battery cable after the charging cables are removed. This
procedure will prevent the possibility of a short circuit and sparks if
you make accidental contact between a battery terminal and the
vehicle's frame or body.
CAUTION:
• Do not attempt to start an automobile engine with the generator still
connected to the battery. The generator may be damaged.
• Connect the positive battery terminal to the positive charging cord.
Do not reverse the charging cables, or serious damage to the
generator and/or battery may occur.
CHARGING CABLE
(Optional parts for all types,
except U type)
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