Dometic DC-Kit PP12 Instructions De Montage Et De Service page 17

DC-Kit PP12, DSP-T12/24 Technical description
Supply from the battery with motor switched on
If the light system voltage exceeds the voltage value Ue (UD+ > Ue), relay contact
Batt. 1/Batt. 2 of the power relay closes. The starter battery and the consumer
battery are therefore connected in parallel with low resistance and are charged
together by the light system. In addition, the contact I2/I4 opens. This activates the
air conditioning unit.
If the light system voltage falls below the switch-off value Ua for the charging current
distributor due to the high load from the air conditioning unit, relay contact Batt. 1/
Batt. 2 opens and the parallel connection between the starter battery and the con-
sumer battery ends. The light system now charges the starter battery. If the vehicle
has a connecting cable between the two batteries, the consumer battery is also
charged.
In addition, the contact I2/I4 closes. This switches off the compressor of the air
conditioning unit. The air conditioning unit fan and the inverter remain in operation.
The lower limit value Ua can be adjusted for ECL-76 and ECL-102 (10.5 V – 12.5 V).
For ECL-103, the voltage value Ua is 23.4 V.
As soon as the voltage in the consumer battery has reached the switch-on value Ue
for the charging current distributor, the compressor of the air conditioning unit
switches on again.
If the voltage in the consumer battery drops further and falls below the switch-off
point for the inverter, the inverter switches off.
Supply from the battery with motor switched off
If the vehicle engine is switched off (UD+ = 0 V), relay contact Batt. 1/Batt. 2 and
relay contact I2/I4 are open. The air conditioning unit can be operated and only
takes power from the consumer battery. If the battery voltage falls below
Ubatt = 10.5 V/21 V, the inverter switches off. There is no longer any voltage at
the corresponding socket and the air conditioning unit switches off.
As soon as the power from the consumer battery reaches the inverter's switch-on
point, the socket is supplied with voltage again. The air conditioning unit has to be
switched back on manually.
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