Yamaha CS50 Service Manual page 56

CHECKING AND CHARGING THE BATTERY
NOTE:
Since MF batteries are sealed, it is not possi-
ble to check the charge state of the battery by
measuring the specific gravity of the electroly-
te. Therefore, the charge of the battery has to
be checked by measuring the voltage at the
battery terminals.
1. Remove:
• battery cover
2. Disconnect:
• battery leads
(from the battery terminals)
CAUTION:
First, disconnect the negative battery lead
, and then the positive battery lead
3. Remove:
• battery
4. Check:
• battery charge
a. Connect a pocket tester to the battery ter-
minals.
Positive tester probe
Negative tester probe
NOTE:
• The charge state of an MF battery can be
checked by measuring its open-circuit vol-
tage (i.e., the voltage when the positive ter-
minal is disconnected).
• No charging is necessary when the open-
circuit voltage equals or exceeds 12.8 V.
b. Check the charge of the battery, as shown
in the charts and the following example.
Example
c. Open-circuit voltage = 12.0 V
d. Charging time = 6.5 hours
e. Charge of the battery = 20 ~ 30%
3-26
CHK
ADJ
.
positive battery
terminal
negative battery
terminal