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Table 7-3
Temperature correction values to hydrometer readings
for measuring electrolyte density
Electrolyte temperature, °ë Correction value, g/cm
3
-40 to -26 -0.04
-25 to -11 -0.03
-10 to +4 -0.02
+5 to +19 -0.01
+20 to +30 0.00
+31 to +45 +0.01
With electrolyte temperatures over 30°ë, the correction value
is added to actual hydrometer readings. When electrolyte tem-
perature is below 20°ë, the correction value is subtracted. The
correction value is not applied when electrolyte temperature is
within 20 to 30°ë.
Once you have measured the electrolyte specific gravity in
each battery cell, determine the state of the battery charge using
Table 7-4. Withdraw the battery from the vehicle for re-charging
when it is discharged in excess of 25 percent in winter time or 50
percent in summer time.
When measuring electrolyte density, take care not to drip
electrolyte on the battery cover, case, body or other parts.
Electrolyte contains hazardous sulfuric acid which causes corro-
sion, current leaks, etc.
Do not measure the electrolyte specific gravity in the follow-
ing cases to exclude wrong readings:
- when the electrolyte level is not as required;
- when electrolyte is too hot or too cold; the optimum temper-
ature to measure electrolyte specific gravity is 15-27 ° ë;
- immediately after the battery replenishment. Leave the bat-
tery for some time to let the electrolyte mix up; it may take up to
several hours if the battery has been fully discharged;
- after a number of start-up attempts. It is advisable to wait
until electrolyte in the battery cell is homogeneous in terms of
density;
- when electrolyte is «boiling». Wait to see bubbles rising to
the surface in the electrolyte, sampled with a hydrometer.
Battery charging
Remove the battery from the vehicle and clean it carefully,
especially its top. Check the electrolyte level and replenish, if
applicable.
The battery is recharged at a rate of 5.5 amperes with the
caps undone. Charge the battery until intensive gas escape is
observed and consistent voltage and electrolyte specific gravity is
achieved within three hours. The electrolyte density of the
charged battery at 25 ° ë should be as shown in Table 7-4.
When recharging the battery, frequently check the electrolyte
temperature to keep it below 40 ° ë. When 40 ° ë is reached, then
either halve the charging current or stop recharging to cool the
battery down to 27 ° ë.
Stop charging the battery in case of intensive gas escape
from the battery cells and when the last three measurements
(taken hourly) show no changes in voltage and specific gravity.
If at the end of the recharging procedure the electrolyte spe-
cific gravity (after temperature correlation) differs from that spec-
ified, adjust it accordingly. In case of higher specific gravity,
remove some electrolyte and top up distilled water, while in case
of lower specific gravity - remove some amount of lower specific
gravity electrolyte and add some higher specific gravity elec-
trolyte (1.4 g/cm
3
).
After the electrolyte specific gravity has been duly adjusted,
continue to charge the battery further 30 minutes for better elec-
trolyte mixing. Next disconnect the battery and after 30 minutes
check the electrolyte level in all cells.
When electrolyte is below the level required, pour in elec-
trolyte of the specific gravity which is recommended for that cli-
mate (Refer to Table 7-4). When electrolyte level is above that
required, remove excessive amount using a rubber bulb.
139
Table 7-4
Electrolyte specific gravity at 25°ë, g/cm
3
Climate (average Season Fully discharged Battery discharged
January temperature, °ë battery by 25% by 50%
Very cold (from -50 to -30) Winter 1.30 1.26 1.22
Summer 1.28 1.24 1.20
Cold (from -30 to -15) All seasons 1.28 1.24 1.20
Moderate (from -15 to -8) All seasons 1.28 1.24 1.20
Warm and damp (from 0 to +4) All seasons 1.23 1.19 1.15
Hot and dry (from -15 to +4) All seasons 1.23 1.19 1.15