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SECTION 4.4
DIAGNOSTIC TESTS
Page 125
B. Perform a load test on the Battery:
(Maintenance Free Battery)
1. Using a lead acid battery load tester test the load
capability of the battery.
2. Follow the load tester’s manufacturer’s instructions carefully.
Figure 3. A Typical Battery Load Tester
C. Te s t B a t t e r y S t a t e o f C h a r g e :
(Non-Maintenance Free Battery)
1. Use an automotive type battery hydrometer to test
battery state of charge.
2. Follow the hydrometer manufacturer’s instructions
carefully. Read the specific gravity of the electrolyte
fluid in all battery cells.
3. If cells are low, distilled water can be added to refill cell
compartment.
4. If the hydrometer does not have a “percentage of charge”
scale, compare the reading obtained to the following:
a. An average reading of 1.260 indicates the
battery is 100% charged.
b. An average reading of 1.230 means the battery
is 75% charged.
c. An average reading of 1.200 means the battery
is 50% charged.
d. An average reading of 1.170 indicates the bat-
tery is 25% charged.
CHECK EACH CELL
AFTER CHARGING
USE A TEMPERATURE
COMPENSATED
HYDROMETER
Figure 4. Using a Battery Hydrometer
5. Test Battery Condition:
a. If the difference between the highest and lowest
reading cells is greater than 0.050 (50 points),
battery condition has deteriorated and the bat-
tery should be replaced.
b. However, if the highest reading cell has a
specific gravity of less than 1.230, the test
for condition is questionable. Recharge the
battery to a 100 percent state of charge, and
then repeat the test for condition.
RESULTS:
1. Remove the battery and recharge with an automotive
battery charger, if necessary.
2. If battery condition is bad, replace with a new battery.
LIQUID
LEVEL
1220
1230
1240
1250
1260
1270
80°
0
4
8
12
16
20
24
28
32
4
8
12
16
20
24
28
32
26.6°
Cell # Specific Gravity
1 1.255
2 1.260
3 1.235
4 1.250
5 1.240
6 1.225
HIGH READING
LOW READING
35 POINTS DIFFERENCE
Figure 5. Reading a Battery Hydrometer
DC CONTROL
PART 4