Closed-Circuit Current

Closed-circuit Current Measurement Using The Of The Intelligent Battery
Sensor

Description
In the event of problems with increased closed-circuit current, it is frequently the case that this must be determined during Service. With the conventional procedure, a shunt resistor must be fitted at the ground strap of the vehicle.

Evaluating of the closed-circuit current monitoring:
On vehicles with an IBS (Intelligent Battery Sensor), the DME/DDE monitors the closed-circuit current when in the idle state.

The IBS is only fitted with certain equipment options (e.g. M-ASK or CCC). The test module for evaluating of the closed circuit current monitoring first of all tests whether an IBS is fitted at all.

In this model series, the results of the last 32 cycles of closed-circuit current monitoring are stored in the DME/DDE. A new cycle of closed-circuit current monitoring is stored under the following conditions:
- Terminal R is off for at least 70 minutes.
- The vehicle is in the idle state for at least another 120 minutes without being wakened.

If these conditions are met, the result of the closed-circuit current monitoring is stored in a new cycle. The oldest cycle of the 32 cycles is overwritten by the new cycle.

If the vehicle is wakened after saving a cycle, a new cycle can then begin if the conditions are met.

The result of a cycle of closed-circuit current monitoring has two categories:
1. In the first category, whether or not an auxiliary consumer unit was logged in during the idle state (at least 120 minutes) is stored. An auxiliary consumer unit is a consumer unit that can also be activated in the idle state of the vehicle. In the case of closed-circuit current monitoring, a distinction can be made with regard to logged in auxiliary consumer units:
- No auxiliary consumer unit was logged in
- A statutory auxiliary consumer unit was logged in (e.g. light or hazard warning lights)
- The independent heating was logged in
- Another auxiliary consumer unit was logged in
2. In the second category, the range of the closed-circuit current during the idle state (at least 120 minutes) is stored.
In the case of closed-circuit current monitoring, a distinction can be made with regard to closed-circuit current:
- 0-80 mA (normal closed-circuit current in the idle state without auxiliary consumer units)
- 80-200 mA
- 200-1000 mA
- Over 1000 mA

Increased closed-circuit current in a cycle can be seen above all when no auxiliary consumer unit was logged in, but the closed-circuit current was above 80 mA.

Bear in mind that in the event of problems with the idle state of the vehicle no new cycles for closed-circuit current monitoring are stored. If the vehicle does not 'go to sleep', e.g. due to a 'sleep preventer', no new cycle of closed-circuit current monitoring is stored. Saving a new cycle of closed-circuit current monitoring is also prevented if the vehicle is permanently wakened by a control module or a user.