Honda TRX450ER Owner's Manual page 172

Battery ( TRX450ER only)
Battery Charging
Refer to Saf ety Precautions on page 77 .
(1)
(1) ''trickle'' charger
Be sure to read the information that came with your battery charger and
follow the instructions on the battery. Improper charging may damage
the battery.
We recommend using a ''trickle'' charger ( ) for home charging. These 1
units can be left connected for long periods without risking damage to
the battery. However, do not intentionally leave the charger connected
longer than the time period recommended in the charger's instructions.
Avoid using an automotive-type battery charger. An automotive charger
can overheat an ATV battery and cause premature damage.
Servicing Your Honda 163