Cub Cadet 900 Series Professional Shop Manual page 128

ELECTRICAL SYSTEM
4. Battery discharge test
Occasionally a battery will discharge while sitting
unused. To test for a battery that is "leaking" voltage:
4a. Confirm that operator technique is not cre-
ating a situation that causes a draw. As an
example, if a homeowner habitually turns
their equipment off using a safety switch
(perhaps vacating the seat with the key
switch still ON), that may leave a relay or
fuel shut-off solenoid energized.
4b. Disconnect and charge the battery fully.
4c. Use the ammeter function of a DMM to
check for a power draw between the nega-
tive post on the battery and the end of the
ground cable that normally connects to it.
There should be no significant D.C.
Amperage flow. See Figure 7.44.
Figure 7.44
NOTE: A spark jumping from the post to the
cable end is an indication that there is a substan-
tial current draw, but should not be used repeat-
edly as a diagnostic tool. This is an extremely
unkind thing to do to any electronic components
of the tractor.
4d. Once the presence of a draw is confirmed,
disconnect components of the system one
at a time while monitoring an ammeter to
see which makes the draw stop.
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4e. If the battery is being checked indepen-
dently of the equipment it powers, mea-
sure and note the battery voltage while it is
disconnected, over a three-day period.
4f. There should be less than a .2 volt drop in
the readings. If there is more than a .2 volt
drop, the battery is bad.
5. Storage of batteries
5a. Always store a battery with a full charge
(unless the battery is a dry battery and the
electrolyte has not been added yet). This
may require periodic re-charging.
5b. Take measures to prevent the battery from
freezing in cold weather. The electrolyte in
a fully charged battery has a lower freezing
point than the electrolyte in a battery with a
lower state of charge.
5c. Store the battery in a cool, dry place.
5d. If storing multiple batteries (primarily store
stock), rotate the stock so that the oldest
battery goes out first. This will increase the
life of the batteries.
6. Troubleshooting
6a. The first step in troubleshooting is to
always verify the complaint. Defining and
verifying the problem reduces the possibil-
ity of misunderstanding and helps clarify
the diagnostic approach.
6b. The next step is to check the simple stuff
first:
• Check the fuse or fuses. Some models have
ground side fuse. Failure of any fuse is an indi-
cation that there is a problem of some sort in the
circuit that the fuse protects.
• Look for obvious physical damage.
• Use the hour meter and indicator lamps as a
guide to direct the search. As an example, when
diagnosing a "no-crank" condition on a lawn trac-
tor with a PTO safety switch: if the PTO light is lit
on the hour meter but the technician has visually
verified that the PTO clutch is not engaged, the
PTO circuit would be a reasonable place to
check for problems.
• Check the battery. A valid diagnosis of many
systems cannot be made without full system
voltage applied.