Battery Testers; Testing The Battery - Craftsman 28906 Professional Shop Manual

ELECTRICAL SYSTEM
lb.
10.
ld.
Give the battery at least ten minutes for the
electrolyte to stabilize after charging the
battery or adding water to the cells.
Measure the temperature of the electrolyte
in the middle cells of the battery.
Squeeze the bulb on the hydrometer, then
insert the hose into the cell.
le. Release the bulb, drawing electrolyte into
the hydrometer to the fill line.
IMPORTANT: Hold the hydrometer straight up
and down when drawing up the electrolyte. The
float needs to float free, not rubbing against the
sides of the hydrometer.
lf.
lg.
Write down the specific gravity of each cell.
The readings must be corrected for the
temperature of the electrolyte. The
hydrometer manufacture should list the
temperature the float is calibrated to. Most
are calibrated to 80 ° . To correct the read-
ing, add .004 to the reading for every 10°
above the calibrated temperature or sub-
tract .004 for every 10° below the cali-
brated temperature.
lh. Compare the reading to the chart.
Specific Gravity Charge Condition
1.265 Fully Charged
1.225 75% Charged
1.190 50% Charged
1.155 25% Charged
1.12 Fully Discharged
Battery Testers:
There are two major ways to check a battery's opera-
tion :
Load test that checks the out-put of the battery
after the fully charged battery has done a certain
amount of work. Fixed load testers are com-
monly available. Variable load testers are not
generally found in outdoor power equipment
repair shops, but are better for testing batteries.
Capacitance test that checks the condition of the
battery plate core, regardless of the level of
charge.
Testing the battery:
1. Adjustable load testing
Adjustable load testing is used if an adjustable load
tester is available. Follow the procedures specified by
the manufacturer of the tester to connect to the battery.
la. Disconnect the battery cables.
IMPORTANT: Disconnect the negative cable
first to help prevent a shorting hazard.
lb. Measure the temperature of the electro-
lyte.
lc. Connect a voltmeter and the load tester to
the appropriate terminals.
ld. Hook an amp probe onto the ground lead
of the load tester.
NOTE: A shunt can be used in place of the amp
probe, but a second voltmeter will be needed to
get a measurement from the shunt.
le. Apply a load equal to 50% of the battery's
rated CCA for 15 seconds.
,
Electrolyte test using a Refractometer to check
the density of the electrolyte by measuring the
degree to which light waves bend when passing
through the electrolyte.
IMPORTANT: To prevent damage to the charg-
ing system disconnect the battery to charge it.
NOTE: If battery needs to be charged, let battery
sit for ten minutes to stabilize after charging.
Apply a load to the battery for 15 seconds to
remove the surface charge. Then re-check the
battery.
29