Kubota ZD221-48 Workshop Manual page 224

ZD221, WSM
ELECTRICAL SYSTEM
Battery Specific Gravity
1. Check the specific gravity of the electrolyte in each cell with a
hydrometer.
2. When the electrolyte temperature differs from that at which the
hydrometer was calibrated, correct the specific gravity reading
following the formula mentioned in (Reference).
3. If the specific gravity is less than 1.215 (after it is corrected for
temperature), charge or replace the battery.
4. If the specific gravity differs between any two cells by more than
0.05, replace the battery.
• NOTE
• Hold the hydrometer tube vertical without removing it from
the electrolyte.
• Do not suck too much electrolyte into the tube.
• Allow the float to move freely and hold the hydrometer at eye
level.
• The hydrometer reading must be taken at the highest
electrolyte level.
(Reference)
• Specific gravity slightly varies with temperature. To be exact, the
specific gravity decreases by 0.0007 with an increase of 1 °C
3EEABAB1 P035A
(0.0004 with an increase of 1°F) in temperature, and increases
by 0.0007 with a decreases of 1 °C (0.0004 with a decrease of 1
OF).
Therefore, using 20°C (68 OF) as a reference, the specific gravity
reading must be corrected by the following formula:
- Specific gravity at 20°C
=
Measured value + 0.0007
x
(electrolyte temperature - 20 0c)
- Specific gravity at 68 OF
=
Measured value + 0.0004
x
(electrolyte temperature - 68 OF)
3EEABAB1 P034A
o
x x
Specific Gravity Stale of Charge
1.260 Sp. Gr.
100 % Charged
1.230 Sp. Gr. 75 % Charged
1.200 Sp. Gr. 50 % Charged
1.170 Sp. Gr. 25 % Charged
1.140 Sp. Gr. Very Little Useful Capacity
1.110 Sp. Gr. Discharged
At an electrolyte temperature of 20°C (68 OF)
W1015530
5-S6