Mahindra 2810, Service Manual

Page: 186 / 223

SECTION 3. BATTERY
1.INSPECTION
1.1 INSPECTION OF ELECTROLYTE LEVEL
As the battery repeats charging and
discharging during operation.The water
content in the electrolyte gradually evaporates,
and as a result,the level should be inspected at
the specific level;replenish with distilled water.
Fig.10-1 electrolyte level
1.2 INSPECTION OF ELECTROLYTE
SPECIFIC GRAVITY
The specific gravity of the electrolyte lowers
as the battery discharges,so the battery
condition can be determined by measuring the
specific gravity.The specific gravity can be
measured generally with a suction type
hydrometer which must be read properly as
shown in Fig. 10-2
Fig.10-2 electrolyte gravity
Note:
When the distilled water is added,charge the
battery to mix it well into the electrolyte before
measuring the specific gravity.
a.Temperature correction of the hydrometer
reading
The specific gravity of the battery
electrolyte(diluted sulfuric acid) varies with the
temperature of the electrolyte at a rate 0.0007
specific gravity point for each 1
℃
change in
temperature.Therefore, when the specific gravity
of the electrolyte in the battery is measured with
a suction type hydrometer,a temperature
correction should be made,using the following
formula to permit the direct comparison of the
measured valve with the standard specific gravity
at 20
℃
.
S
20
:St+0.0007(t-20)
S
20
:Specific gravity at standard
temperature of 20
℃
.
t : Temperature of the electrolyte
at the time of measurement
St : Specific gravity of the
electrolyte measured at t
℃
.
1.3 BATTERY CHARGING
If the specified gravity of the battery electrolyte
in lower than 1.220 (at 20
℃
),the battery should
be recharged,because leaving an undercharged
battery without recharging it will lead to
permanent battery damage.The battery is subject
to self-discharge at a rate as shown in the table
below.Therefore it should be recharged from
time to time when storing the battery unused for
a long period of time.
When recharging the battery,wash clean the
outside of the battery case and the battery
posts.Check the level of the electrolyte in each
cell and replenish with distilled water as
necessary.
0.005 0.025 5
℃
0.001 0.15 20
℃
0.002 1 30
℃
Decrease in
specific gravity
per day Self-discharge
rate per day
(%)
Temperature
10-2