Yamaha WR250F Owner's Service Manual page 81

3. Remove:
• Battery band
• Battery
4. Measure:
• Battery charge
Measurement steps:
a. Connect a pocket tester "1" to the
battery terminals.
→
Tester positive probe
positive terminal
→
Tester negative probe
negative terminal
• The charge state of an MF battery
can be checked by measuring its
open-circuit voltage (i.e., the volt-
age when the positive terminal is
disconnected).
• No charging is necessary when the
opencircuit voltage equals or ex-
ceeds 12.8 V.
b. Check the charge of the battery,
as shown in the charts and the fol-
lowing example.
Example
Open-circuit voltage = 12.0 V
Charging time = 6.5 hours
Charge of the battery = 20–30%
A. Relationship between the
open-circuit voltage and the
charging time at 20 °C (68 °F)
(These values vary with the
temperature, the condition of
the battery plates, and the
electrolyte level.)
B. Open-circuit voltage
C. Charging time (hours)
D. Time (minutes)
battery
E. Charging condition of the bat-
tery
battery
F. Ambient temperature 20 °C
(68 °F)
a. Charging
b. Check the open-circuit volt-
age
5. Charge:
• Battery
(refer to the appropriate charging
method illustration)
Do not quick charge a battery.
• Never remove the MF battery
sealing caps.
• Do not use a high-rate battery
charger since it forces a high-
amperage current into the bat-
tery quickly and can cause bat-
tery overheating and battery
plate damage.
• If it is impossible to regulate the
charging current on the battery
charger, be careful not to over-
charge the battery.
• When charging a battery, be sure
to remove it from the machine. (If
charging has to be done with the
battery mounted on the machine,
disconnect the negative battery
lead from the battery terminal.)
3-28
ELECTRICAL
• To reduce the chance of sparks,
do not plug in the battery charger
until the battery charger leads
are connected to the battery.
• Before removing the battery
charger lead clips from the bat-
tery 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 gener-
ate 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, disconnect
the battery charger and let the
battery cool before reconnecting
it. Hot batteries can explode!
• As shown in the following illus-
tration, the open-circuit voltage
of an MF battery stabilizes about
30 minutes after charging has
been completed. Therefore, wait
30 minutes after charging is com-
pleted before measuring the
open-circuit voltage.