TRUCK SERVICE MANUAL
Fig. 10 Removing Vent Manifold to Gain Access to Cells
(Side Terminal Maintenance Free Battery)
section of the plaque, individual caps can be
unscrewed to allow access to each cell. When
reinstalling cell caps after testing, make sure caps
are properly seated.
c. If electrolyte level is above the plates in all cells,
proceed to Step 2.
d. If electrolyte level is below the tops of the plates in one
or more cells, add water until electrolyte level is just
above the tops of the separators. Charge the battery
15 minutes at 15-25 amperes to mix the water with
the electrolyte. After mixing electrolyte, proceed to
STEP 2. SPECIFIC GRAVITY (HYDROMETER) TEST
Perform specific gravity (hydrometer) test on all cells. (Refer
to instructions for reading hydrometer under ELECTROLYTE
AND SPECIFIC GRAVITY.)
a. Measure and record specific gravity, corrected to 26.7° C
(80° F), of each cell. Compare readings obtained with Table 4
to determine battery's state of charge.
Fig. 11 Removing Section of Top Plaque to
Gain Access to Cell Caps
(Top Terminal Maintenance Free Battery)
Specific Gravity (Corrected to
26.7° C or 80° F)
State of Charge
b. If specific gravity readings of all cells are 1.225 or
higher when, corrected to 26.7° C (80° F), proceed to
c. If specific gravity readings are low (below 1.225) but
are within 50 points (.050 specific gravity) between
highest and lowest cells, recharge battery as
instructed under CHARGING and inspect vehicle's
electrical system to determine cause for low charge.
After charging battery, proceed to Step 3.
d. If specific gravity readings vary more than 50 points
(.050 specific gravity) between cells, replace the
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