Yamaha YZ 2019 Series, Owner'S Service Manual, Page: 358 / 398

ELECTRICAL COMPONENTS
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plug in the battery charger until the battery
charger leads are connected to the battery.
• Before removing the battery charger lead
clips from the battery terminals, be sure to
turn off the battery charger.
• Make sure the battery charger lead clips are
in full contact with the battery terminal and
that they are not shorted. A corroded bat-
tery charger lead clip may generate heat in
the contact area and a weak clip spring may
cause sparks.
• If the battery becomes hot to the touch at
any time during the charging process, dis-
connect the battery charger and let the bat-
tery cool before reconnecting it. Hot
batteries can explode!
• As shown in the following illustration, the
open-circuit voltage of a VRLA (Valve Reg-
ulated Lead Acid) battery stabilizes about
30 minutes after charging has been com-
pleted. Therefore, wait 30 minutes after
charging is completed before measuring
the open-circuit voltage.
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Charging method using a variable-current
(voltage) charger
a. Measure the open-circuit voltage prior to
charging.
TIP
Voltage should be measured 30 minutes after
the engine is stopped.
b. Connect a charger and ammeter to the bat-
tery and start charging.
TIP
Set the charging voltage to 16–17 V. If the set-
ting is lower, charging will be insufficient. If too
high, the battery will be over-charged.
c. Make sure that the current is higher than the
standard charging current written on the bat-
tery.
TIP
If the current is lower than the standard charging
current written on the battery, set the charging
voltage adjust dial at 20–24 V and monitor the
amperage for 3–5 minutes to check the battery.
d. Adjust the voltage so that the current is at the
standard charging level.
e. Set the time according to the charging time
suitable for the open-circuit voltage.
f. If charging requires more than 5 hours, it is
advisable to check the charging current after
a lapse of 5 hours. If there is any change in
the amperage, readjust the voltage to obtain
the standard charging current.
g. Measure the battery open-circuit voltage after
leaving the battery unused for more than 30
minutes.
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Charging method using a constant voltage
charger
a. Measure the open-circuit voltage prior to
charging.
TIP
Voltage should be measured 30 minutes after
the engine is stopped.
b. Connect a charger and ammeter to the bat-
tery and start charging.
c. Make sure that the current is higher than the
standard charging current written on the bat-
tery.
TIP
If the current is lower than the standard charging
current written on the battery, this type of battery
charger cannot charge the VRLA (Valve Regu-
lated Lead Acid) battery. A variable voltage
charger is recommended.
d. Charge the battery until the battery’s charg-
ing voltage is 15 V.
A. Open-circuit voltage (V)
B. Time (minutes)
C. Charging
D. Ambient temperature 20

C (68

F)
E. Check the open-circuit voltage.
• Standard charging current is reached
Battery is good.
• Standard charging current is not reached
Replace the battery.
12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.