2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 137Get this manual
CHECKING THE BATTERY Open-circuit voltage (V)
Relationship between the open-circuit voltage and the charging time at 20 C
the condition of the battery using the following chartsExample: Open-circuit voltage12.0 Charging time6.5 hours Charge condition of the battery2030 Charging method for MF batteries
Charging time (hours) These values vary with the temperature, the condition of the battery plates, and the electrolyte level
CAUTION: