Cub Cadet Fun Runner - Manual (Page 99)

5-31
BATTERY PACK EVALUATION
As batteries age and acquire more cycles on
them, they begin to loose capacity. A cycle
is one complete charge and discharge
event. The battery’s cycle life is the amount
of charge/discharge cycles it can take before
it no longer meets the minimum capacity
requirements.
There are several factors that effect the
cycle life of a battery. One significant factor
is internal corrosion, which is caused by
oxidation and hydrogen reduction.
Operating in high temperatures accelerates
the corrosion process. Another significant
factor in cycle life is the depth of discharge.
The deeper the discharge, the more difficult
it becomes to reverse the chemical reaction
during charging. This results in a loss of
active material available for use in the next
cycle. A battery that is discharged half way
on each cycle will last for twice as many
cycles as one that is completely discharged
on each cycle.
As the batteries acquire more and more
cycles, they should loose capacity at
approximately the same rate. When all the
batteries in the pack are very close in
capacity the pack is “balanced” or
“equalized.” Under normal circumstances,
the pack should remain balanced throughout
its cycle life, and at the point it can no longer
meet the capacity requirements, it is
replaced.
Occasionally there is a case where one or
more of the modules in the pack degrade at
a different rate than the others causing an
“unbalanced” battery pack. There are
several factors that can cause this. When a
pack is unbalanced, each charge/discharge
cycle worsens the condition. The result is
that the pack reaches the point of not having
enough capacity prematurely. The pack is
only as good as its weakest module. An
unbalanced pack will accelerate the capacity
loss of the weak module.
To ensure a balanced pack, battery
modules on the FunRunner should be
replaced as a set. Replacing only one or
two modules will lead to further imbalance
problems even if the remaining modules test
ok. The new modules will not be at the
same capacity as the old and the imbalance
will worsen with continued cycles.
Charging the batteries for long periods of
time occasionally will help to keep the
battery pack balanced.
Since the battery modules are sealed gel
type, specific gravity cannot be checked. A
voltage measurement is the only means of
evaluating each module.
Before connecting the voltmeters for testing
batteries, inspect the pack thoroughly. Look
for loose, corroded, or discolored terminals.
Corrosion on the terminals should be from
none to very minimal on sealed batteries.
Excessive corrosion may be an indication
that the module has lost its seal at some
point. Inspect the case for cracks or
damage. Also look for modules that are
swollen or bulged out on the sides. Faulty
modules will often swell or bulge. The
module cases should all feel about the same
temperature during or after operation. Bad
modules will often feel much hotter than a
good module. Be very careful when
feeling module temperature so as to not
touch any high voltage terminals.
After a thorough inspection, you can test the
pack using voltage measurements. Use the
following procedures to evaluate the battery
pack condition:
Quick Test
•
Connect a voltmeter across the main
terminals of the battery pack.
•
Voltage should be 49 volts or more.
•
Charge batteries some if voltage is low.
•
Drive vehicle and determine if power
and acceleration seem normal (voltage
must stay above 46 volts during test).
•
If vehicle performance and power seem
normal and no fault indications are
given, then the battery pack has most
likely lost capacity if the range has
diminished.
•
Check charger operation to make sure
batteries are getting a full charge (see
“Testing Charger Operation”). If