Revision Date
– 22/12/2014
page 26
Calculate the voltage drop by using the formula
below.
If the voltage drop is greater than 0.5 V in a 12V
DC system, significant voltage drop is present
within the circuit while the fridge is running.
TEST OUTCOMES
– VOLTAGE DROP TEST
1. Voltage drop detected
If a significant voltage drop (greater than 0.5 volts for a 12V DC system) is detected, the following checks
should be undertaken.
A.
Check the size of the wiring used in the circuit.
A dedicated wiring circuit should be installed to power the fridge freezer. This circuit should be as
short as practical and should be connected directly to the power supply via a suitable fuse.
Use a 15 Amp fuse for 12V DC applications and a 7 Amp fuse for 24V DC applications.
For cable lengths up to 6m (20’), use a minimum automotive cable size of 6 mm (approx 4.5
mm
2
).
For cable lengths greater than 6m (20’), consult a qualified auto electrician for advice on the
correct wire size.
For best performance, the negative wire of the circuit should be connected directly to the negative
terminal of the battery. It should not be grounded directly to the vehicle body or chassis.
B.
Check that all terminals and joints are clean and in good condition.
C.
Check that the voltage at the supply socket (
VOLTAGE B
) is above the cut-out voltage for the
selected battery protection setting (refer to section
D.
Check that the supply socket is not attached to the vehicle ignition switch. If it is, make sure that the
ignition switch is not turned off.
2. Measured voltage below cut-out voltage
If the voltage measured at the supply socket (
VOLTAGE B
) is below the cut-out voltage for the current
battery protection setting (refer to section
), the compressor will not run and the error light will flash
once every 5 seconds. In this case, the correct battery protection setting should be selected or the
supply cable upgraded to 4.5mm
2
to minimise voltage drop
3. Low voltage detected at both battery and supply socket
If low voltage is detected at both the battery (
VOLTAGE C
) and the supply socket (
VOLTAGE B
), it is
recommended that the battery be charged or replaced.
VOLTAGE
DROP
VOLTAGE
‘A’
VOLTAGE
‘B’
=
-
