Volvo Penta D2-55, Workshop Manual

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Group 30 Electrical system
Load testing the battery
The battery acid density may not be less than
1.21 g/cm
3 .
1. Fix a voltmeter across the battery poles
2. Activate the stop function and run the starter mo-
tor for about 10 seconds with the glow plugs acti-
vated and read off the start voltage. It should not
be less than 9.5 V.
3. Check if any of the cells bubble when the starter
motor is operated (short-circuit cell).
4. If the voltage is less than 9.5 V or if any of the
cells bubble:
Replace the battery and try again.
If the voltage is 9.5 V or higher:
The battery is OK. Check the charging voltage
(see next paragraph).
Checking charge status
Check the charge status with an acid densitometer.
Measure the acid density of all cells at +25
o C. Mea-
surement shall not be done immediately after charging
or filling with battery water.
The acid density of a fully charged battery at +25 o C
shall be 1.28 g/cm 3 . Charge the battery if the acid
density is less than 1.24 g/cm 3 (approx. 75 %
charged). Charge at 5-6A for 10 hr.
WARNING! The battery generates hydrogen gas
which is easily ignited and highly explosive.
Never expose the battery to naked flame or
electrical sparks. Ventilate the battery area well,
especially after charging.
Check 2hr. after charging
If the acid density of the cells is uneven, a cell is
probably short circuit. Replace the battery if the differ-
ence between cells is 0.04 g/cm
3 or more (i.e. 1.28-
1.24 g/cm 3 ).
If the acid density between cells is even, then the bat-
tery is not fully charged.
Sulfated battery. A minor case of sulfating can be bro-
ken down by an additional 10 hours charging. Replace
the battery if this does not help.