2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 127Get this manual
CHECKING AND CHARGING THE BATTERY CHK ADJ
NOTE: The charge state of an MF battery can be checked by measuring its open-circuit voltage (i.e the voltage when the positive terminal is disconnected) No charging is necessary when the open-circuit voltage equals or exceeds 12.8 VbCheck the charge of the battery, as shown in the charts and the following exampleExample cOpen-circuit voltage12.0 dCharging time6.5 hours eCharge of the battery2030
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