DAF CF65, CF75, CF85 Series . Manual — part 509
5
CF65/75/85 series ≥0E621376
Checking batteries
BATTERIES
4-1
4. CHECKING BATTERIES
4.1 VISUAL INSPECTION
-
A white dividing line at
1
/
3
of the plate height
(this can be seen through transparent
battery boxes) indicates that the battery has
been left in a deeply discharged condition.
-
If the electrolyte is brown and the battery
consumes a lot of fluid, this indicates that
the battery is overcharged.
-
If the electrolyte is turbid and milky and the
cells have a white deposit, the battery has
become damaged due to insufficient
charging (deep discharge).
4.2 CHECKING THE CHARGING CONDITION
Relative density
-
The charging and discharging of the battery
leads to a chemical reaction in the battery,
which involves sulphuric acid. The sulphuric
acid concentration drops as the battery
discharges.
The concentration, measured as relative
density (kg/dm
3
) is a useful indicator in
determining the charging condition of the
battery.
-
An acidimeter can be used to check the
charging condition.
Relative density at 27_C in kg/dm
3
Charged battery
: 1.28
Half-charged battery
: 1.20
Discharged battery
: 1.10
-
Measurement corrections are necessary if
temperatures are significantly lower or
higher. For every 10_C lower temperature,
subtract 0.007 points from the measured
value. For every 10_C higher temperature,
add 0.007 points.
In batteries that are in good condition, the
relative density should be the same in all
the cells. The difference between the
highest and lowest relative density must not
exceed 0.03 kg/dm
3
.
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200404
5
BATTERIES
Checking batteries
CF65/75/85 series ≥0E621376
4-2
Note:
If the relative density in one of the cells is
much lower than in the other cells it may be
caused by cell closure. If the relative
relative density of two adjacent cells is
much lower than in the other cells, this
indicates a leakage in the cell partition. In
both cases, the battery must be replaced.
Voltage
-
The charging condition of the batteries can
be measured using a sensitive, preferably
digital voltmeter. This method can only be
used 1 to 2 hours after full completion of
charging or discharging. Measure the
absolute rest voltage (the positive and
negative terminals of the battery must be
removed).
The charging condition of the battery can be
calculated using the formula: Voltage per
cell = relative density (kg/dm
3
)+0.84.
For example:
For a fully charged battery, the relative
density per cell is 1.28 kg/dm
3
. The voltage
per cell is therefore 1.28 + 0.84 = 2.12 V.
A 12V battery has 6 cells. The total voltage
for a charged battery is 6 x 2.12 = 12.72 V.
The voltage of a half-charged battery is
approx. 12.24 V.
The voltage of a discharged battery is
approx. 11.75 V.
4
200404
5
CF65/75/85 series ≥0E621376
Checking batteries
BATTERIES
4-3
4.3 CHECKING USING A BATTERY TESTER
-
The general condition of the battery can be
checked quickly using a battery tester. For
this check, a load is applied to the battery,
and then the discharge voltage at the
battery terminals is measured. The load
applied to the battery must be at least 3
times the capacity of the battery.
-
As a rule, the test can be carried out when
the battery is sufficiently charged (relative
density 1.25 - 1.28 kg/dm
3
).
At normal temperatures (10-20_C), the
charging voltage for a properly charged
battery must be 10 volts after 10 seconds.
In the case of a partially discharged battery
(relative density 1.25 kg/dm
3
), the reading
should be at least 9 volts.
It is important that the voltage is measured
directly at the battery poles.
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200404
5
BATTERIES
Checking batteries
CF65/75/85 series ≥0E621376
4-4
4
200404
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