Honda FourTrax Rancher TRX420FA5 2019 Owner's Manual page 195

Battery Storage
Refer to Safety Precautions on page 107.
If you plan to store your ATV, we recommend you remove the
battery and store it where it can be charged at least every 30 days to
maintain its service life.
If you do not remove the battery, we recommend disconnecting the
battery cables (negative cable first).
You will get the best storage results from removing the battery and
slow charging it every 30 days (see Battery Charging, page 188).
Before you remove the battery, be sure to read all the information
that follows, as well as the information on the battery label.
WARNING
The battery gives off explosive hydrogen gas
during normal operation.
A spark or flame can cause the battery to
explode with enough force to kill or seriously
hurt you.
Wear protective clothing and a face shield, or
have a skilled mechanic do the battery
maintenance.
WARNING
3
Battery
Servicing Your Honda 185