Product Manual
Table Of Contents
TP-6905 7/18 63Section 4 Scheduled Maintenance
4.8.1 Checking Electrolyte Level
Check the electrolyte level of batteries with filler caps
monthly. Remove filler caps and verify that electrolyte
level reaches bottom of filler holes. Refill as necessary
with distilled water. DO NOT add fresh electrolyte.
Tighten all filler caps. If water is added during freezing
temperatures, run the generator set for 20--30 minutes
to mix the electrolyte and water to prevent battery
damage from freezing.
4.8.2 Checking Specific Gravity
Use a battery hydrometer to check the specific gravity of
the electrolyte in each battery cell. While holding the
hydrometer vertically, read the number on the glass bulb
at the top of the electrolyte level or the number adjacent
to the pointer. If the hydrometer used does not have a
correction table, use the correction factors in
Figure 4-14. Determine specific gravity and electrolyte
temperature of battery cells. Locate temperature in
Figure 4-14 and adjust the specific gravity by the
amount shown.
The battery is fully charged if the specific gravity is 1.260
at an electrolyte temperature of 80F (26.7C). The
difference between specific gravities of each cell should
not exceed 0.01. Charge the battery if the specific
gravity is below 1.215 at an electrolyte temperature of
80F (26.7 C). See Figure 4-12.
Specific Gravity,
Corrected to
80F (26.7C)
Battery
Condition
Below 1.215 Needs charging
1.260 Fully charged
Figure 4-12 Specific Gravity Interpretation
Some battery testers have four or five beads in the test
tube. Draw electrolyte into the tube as performed with
the battery hydrometer described previously. Use the
manufacturer’s instructions. Figure 4-13 interprets
typical test results.
Number of Floating Beads
Battery
Condition
5 Overcharged
4 Fully charged
3 Good charge
1or2 Low charge
0 Dead battery
Figure 4-13 Bead-Type Test Interpretation
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
-- 1 2 . 2
-- 6 . 7
-- 1 . 1
4.4
10
21.1
26.7
32.2
37.8
43.3
48.9
54.4
60.0
65.6
71.1
15.6
+ .032
+ .030
+ .028
+ .026
+ .024
+ .022
+ .020
+ .018
+ .016
+ .014
+ .012
+ .010
+ .008
+ .006
+ .004
+ .002
0
-- .002
-- .004
--. 006
-- .008
-- .010
-- .012
-- .014
-- .016
-- .018
-- .020
-- .022
-- .024
-- .026
-- .028
C F
EXAMPLE NO. 1—
Temperature below 80F (26.7C)
Hydrometer Reading 1.250
Acid Temperature 20F(--6.7C)
Subtract .024 Specific Gravity
Corrected Specific Gravity is 1.226
1.250 -- .024 = 1.226
EXAMPLE NO. 2—
Temperature above 80F(26.7C)
Hydrometer Reading 1.235
Acid Temperature 100F (37.8C)
Add .008 Specific Gravity
Corrected Specific Gravity is
1.243
1.235 + .008 = 1.243
The temperature correction amounts to about .004 (4 points) of
specific gravity for each 10F(5.5C) change in temperature.
Correction
1-787
Temperature
Figure 4-14 Specific Gravity Temperature Correction