2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 110Get this manual
CHECKING AND CHARGING THE BATTERY Charging method using constant voltage charger
Measure the open-circuit voltage prior to charging
Leave the battery unused for more than 30 minutes before measuring its open-circuit voltage
Connect charger and ammeter to the battery and start charging
Is the amperage higher than the standard charging amperage written on the battery?