JLG sky trak mmv Service Manual page 576

Electrical System
3. Remove the surface charge from any battery that
has just been charged (by a battery charger or by
the vehicle alternator). DO NOT remove the surface
charge from a battery that has been in storage. To
remove the surface charge, apply a 300-ampere
load across the terminals for 15 seconds. Then turn
off the load and wait for 15 seconds to allow the
battery to recover and normalize.
4. Battery temperature should be estimated by touch
and also by the surrounding temperature it was
exposed to during the preceding few hours before
testing. Select the nearest estimated temperature
from the chart below and determine the minimum
voltage that must be maintained while the battery
supplies a specified electrical load.
5. Apply a 260-ampere load test to check the charge
acceptance of the battery. Observe the voltage after
15 seconds with the load connected, then turn off
the load.
Note: The accuracy of this test procedure depends on
closely following the load, time and temperature
specifications.
Relation of Battery Temperature
to Minimum Voltage
Temperature
70° F (21° C) and above
50° F (10° C)
30° F (-1° C)
15° F (-10° C)
0° F (-18° C)
6. If voltage is at or above the value determined in
step 4, the battery is good and may be returned to
service.
7. If voltage is below the value determined in step 4,
check the charge acceptance of the battery one
more time before discarding it. If the voltage
continues to read below the value determined in step
4, replace the battery.
10.96
Minimum Voltage
9.6
9.4
9.1
8.8
8.5
d. Battery Charging
Charge rates between 3 and 50 amperes are generally
satisfactory as long as spewing of electrolyte does not oc-
cur, or the battery does not feel excessively hot (over
125° F [52° C]). Battery temperature can be estimated by
touching or feeling the battery case. If spewing of electro-
lyte occurs or temperature exceeds 125° F (52° C), com-
monly referred to as "boiling" the battery, the charging
rate must be reduced or temporarily halted to permit cool-
ing. Failure to do so will destroy the battery.
When charging a battery, keep this point in mind:
• Battery charging consists of a charge current in
amperes for a period of time in hours. Thus, a
25-ampere charging rate for 2 hours would result
in a 50-ampere hour charge to the battery.
The time required for a charge will vary due to the follow-
ing conditions:
• Size of battery: For example, a completely dis-
charged, large, heavy-duty battery requires more
than twice the recharging as a completely dis-
charged small passenger car battery.
• Temperature: For example, more time will be
required to charge a battery at 0° F than at 80° F.
When a fast charger is connected to a cold bat-
tery, the current accepted by the battery will be
very low at first, then, in time, the battery will
accept a higher rate as the battery warms.
• State of Charge: A completely discharged bat-
tery requires more than twice as much charge as
a half-charged battery. Because the electrolyte is
nearly pure water and therefore a poor conductor
in a completely discharged battery, the current
accepted is very low at first. Later, as the charg-
ing current causes the electrolyte acid content to
increase, the charging current will likewise
increase.
• Charger Capacity: A charger that can only sup-
ply 5 amperes will require a much longer period
of charging than a charger that can supply 30
amperes or more.
Model MMV Rev. 12-04