Webasto Storage Cooler Service Manual

Functional Description

3. Functional Description

3.1

Charging Under Inverter Power

With the vehicle engine running and the charging unit under inverter power only, the voltage regulator for the vehicle alternator determines whether or not the batteries have an acceptable charge.

The voltage regulator will transition through several stages of battery charging, with the first is known as bulk charging. The regulator ramps up the alternator to provide maximum current and will charge the batteries at 14.6V.

The regulator also monitors the battery temperature and battery voltage to determine the charging rate that the batteries are accepting. Bulk charging lasts a minimum of 30 minutes. Once bulk charging is complete, the regulator ramps the current and voltage down, and closes the ground circuit through relay K9, pin-2 which then closes the relay

and allows the compressor to start when all other conditions are satisfied (See Section 3.3).

3.2

Charging Under Shore Power

With the Clean Power system in shore power mode (shore power plugged into 120 VAC source) a signal is sent to relay

K10, pin-1 which then closes the relay and starts the compressor. There is no delay of operation when in the shore power mode due to the fact that the system is receiving its power from an external 120 VAC source. In this case, the inverter is bypassed altogether.

3.3

Charging Mode

3.3.1

Charging (Reference Charge State Diagram in Fig. 15)

3.3.1.1

Charging Conditions

3.3.1.1.1

The charging unit automatically charges the storage cooler assembly when all of the following criteria are satisfied:

• Charge enable switch located on dashboard is switched ON

• Storage core temperature > -3.3°C + 3°C, - 2°C (26.1°F + 5.4°F, - 3.6°F)

• Ambient temperature > 12.8°C ± 3.3°C (55°F ± 6°F)

• High refrigerant pressure < 20.68 bar ± 0.69 bar (300 psig ± 10 psig)

• Low refrigerant pressure > 1.03 bar ± 0.24 bar (15 psig ± 3 psig)

• Battery voltage at acceptable level as determined by voltage regulator when engine is running OR shore power is connected

• Inverter AC voltage present

3.3.1.1.2

Once the criteria outlined in Section 3.3.1.1.1 are met, the charging process

starts. First, the compressor bypass solenoid valve opens for approximately two minutes. This allows the pressures in the high and low sides of the refrigerant system to equalize. At this same time the condenser fan will also turn on. After approximately two minutes, the bypass solenoid valve closes and the compressor starts operation.

3.3.1.1.3

The charging unit automatically stops charging the storage cooler assembly if any of the following conditions are satisfied:

• AC enable switch located on dashboard is switched OFF

• Storage core temperature -3.3°C + 3°C, - 2°C (26.1°F + 5.4°F, - 3.6°F)

• Ambient temperature 12.8°C ± 3.3°C (55°F ± 6°F)

• High refrigerant pressure 20.68 bar ± 0.69 bar (300 psig ± 10 psig)

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