Yamaha UMAX, Service Manual

Page: 280 / 320

ELECTRICAL COMPONENTS (YUM2E)
8-75
2. Record surface voltage from the discharge
unit readout panel.
3. Record the ambient temperature using the
thermometer.
4. Turn the discharge unit “ON” and wait at least
three minutes. If you have a bad connection
or reverse polarity, the discharge unit will au-
tomatically shut off in three minutes.
Correct any problems.
5. Let the discharge unit run until it shuts off and
immediately record the surface voltage from
the discharge unit readout panel. Restart the
discharge unit and let it run until the voltage
reaches 42 V.
6. While the discharge unit is still connected and
operating, measure and record each individ-
ual battery voltage. Look over the voltage
measurements you just recorded. A differ-
ence of 0.5 V from the highest to lowest mea-
surement indicates a weak battery.
WARNING
If the fan is running and you disconnect the
unit, a spark will be produced and could re-
sult in explosion and damage.
7. Turn off the discharge unit. Wait until the fan
stops and then disconnect the battery leads.
Be sure to do the loaded individual battery mea-
surements with the battery pack fully discharged
to 42 V. Failure to do this part of the test imme-
diately after the discharge unit shutoff will allow
the batteries to recover.
Recovered batteries will give false readings.
If more than a few minutes elapse before you do
the individual battery measurements, turn the
discharge unit back on. Allow the discharge unit
to run until the total battery pack voltage is again
approaching 42 V. This will prevent a false
“good” voltage measurement from a recovered
battery.