Electrical Consumption, General

Electrical consumption, general

General
The change from traditional electrical systems with hardware based functions to flexible CAN based electrical systems where a number of nodes govern a large number of software based functions has increased the number of functions in cars. This has also caused an increase in electrical power consumption.
The generator (GEN) has been designed to supply the car with sufficient current for normal electrical loads when driving. The battery functions as a buffer for extreme loads or driving conditions. When the engine is switched off, it is the battery that supplies the car with energy.

Post driving power consuming components

Engine cooling fan (FC)
After driving in hot conditions, the engine cooling fan (FC) may run on for approximately 6 minutes.

Blower fan
After driving with the air conditioning (A/C) on, the blower fan may run for 8 minutes for up to 50 minutes after disengagement to remove moisture from the condenser.

Alarm siren
Note that the battery for the alarm siren starts its charging cycle after the battery poles has been disconnected and then reconnected. This means that the stand-by current consumption can reach 50mA during the first 14 hours.

Power consumption

Ignition setting 0 with closed but not locked doors
Approximately 2 A, after 12 minutes approximately 20 mA (if the siren is not charging).

Ignition switch position I (radio position) with closed doors
Approximately 10 A, after 12 minutes approximately 20 mA (if the siren is not charging).

Hint: Consumption depends on factors such as the radio, interior lighting and blower fan. The power consumption can vary therefore.

Ignition switch position 0 or I with open or incorrectly closed doors
Approximately 6 A, after 12 minutes approximately 1 A (if the siren is not charging). After 20 minutes, the interior lighting switches off and consumption drops to approximately 20 mA.

Hint: Consumption can reach more than 6 A depending on factors such as the radio, door lighting and blower fan.

Door locked and alarm on
Approximately 30 mA depending on the equipment level of the car and the accessories.

Note! It takes approximately 10 minutes before all nodes are closed down after the car is locked.

Other power consuming components that may be running in ignition switch positions I and II
- Blower fan; approximately 4-23 A

Note! A blower fan activated at low speed is not audible in a workshop.

- Radio; approximately 1-6 A
- Low beam; approximately 9 A
- In ignition switch position II, (programming position), all CAN nodes are activated and the automatic low beam system is activated (if applicable).

Battery

Note! The power consumption in a car with the ignition switch in position I or 2 (engine off) can reach in excess of 20 A. In 30-60 minutes, more than 50% of the battery charge status can drain, at which point the plates start to sulfate which causes permanent damage to the battery and reduces its service life. Ensure wherever possible that:
- all doors are closed correctly
- that low beam and the interior lighting is off
- the blower fan is switched off
- deactivate the seat heaters and rear demist.

Connect a battery charger if the repair work allows for this. This applies even when downloading software to nodes, even if the electrical/power consumption is lower than is normal for key position II. Downloads take time, during which the entire CAN network and all associated components are activated. There is also a risk that the data transfer will fail if the system voltage falls below 10.5 V.
For further information about the function of the battery and fault-tracing, see Battery, charging Battery, Charging and Fault-tracing and testing the battery Fault-Tracing and Testing the Battery.