Craftsman 28906 Professional Shop Manual page 34

ELECTRICAL SYSTEM
3. Capacitance testing
There are several brands of capacitance battery testers
presently on the market. Capacitance battery testers
use the battery being tested as their power source.
These testers send a small AC signal through the bat-
tery to measure the capacity of the plate to hold a
charge.
Capacitance testers are very easy to use and are far
less damaging to the battery being tested. For these
reasons, capacitance battery testing is the preferred
method of battery testing.
NOTE: Contact the manufacturer of the tester
being used for specific test procedures.
3a. Connect the tester to the battery.
3b. Set the tester to the CCA rating of the bat-
tery.
3c. Initiate the test.
3d. Read the display of the tester. The tester's
display will indicate if the battery passed or
not. See Figure 7.43.
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.
40.
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 7.43
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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