battery light on

[bdriven]

Hi folks,
I replaced the alternator 3 months ago, bought a chinese one off of ebay.
everything was fine, so this morning drove for 15min, fine, ran(jog) for 1 hour, got back home, going to work as I turned it, the light came on, drove for 30 min, shut the engine off, got my tester, it read, 12.4V, turned it on, read 14.02V.....and guess what, battery light went off ! ???? what gives??? any ideas ???

thx!!!!

[TerminatorX5]

the light illuminates when the voltage bridge is out of balance... it is hard to tell, why it went out of balance and then came back...

[TerminatorX5]

BSD interface to the alternator

The alternator with BSD interface can actively communicate with the engine control unit. The alternator is not linked to the charge indicator lamp, only to the engine control unit. The alternator can detect a variety of faults.
Function

The following functions have been implemented in the engine control unit for the alternator with BSD interface:
-Activating/deactivating the alternator on the basis of appliable parameters
-Specification of the maximum permitted degree of utilisation of the alternator
-Control of the alternator's load response
-Calculation of the alternator moment degree of utilisation
-Diagnosis of the data line between the alternator and the engine control
-Filing of alternator faults in the defect code memory
Activating the load control lamp in instrument cluster via CAN
In comparison to alternators used so far, the display strategy of the load control lamp does not change when the alternator with BSD interface.
The basic function of the alternator is also ensured if the communication between the alternator and the engine control is interrupted.
Possible faults

The following possible faults can be distinguished from fault entries:
High temperature control: The alternator is overloaded; to be safe, the alternator voltage is reduced until the alternator has cooled down again. The charge indicator lamp does not light up.
-Mechanical fault: The alternator is mechanically blocked or the belt drive has failed.
-Electrical fault: Exciter diode defect, excite interruption, overvoltage due to controller defect.
-Communication failure: Line defect between the engine control and alternator.
The following cannot be detected: Coil interruption or short-circuit
Battery charge indicator lamp

The signal for the charge indicator lamp to light up is transferred across CAN to the instrument cluster. The charge indicator lamp lights up if there is mechanical and electrical fault (see above).
Detection

The above-mentioned calculation of the alternator moment and the rate of utilisation of the alternator are heavily dependent on the type (performance) and manufacturer.
This is why the alternator provides the engine control with this data. The engine control adapts its calculation and set values to the exact type.
Aim

The precise calculation of the alternator moment and control of the load response function enables good idling of the engine.
Control of the alternator voltage based on nominal values from the engine control enables a good charge balance of the battery.

[TerminatorX5]

Battery Charge Indicator Lamp

Terminal D+ is replaced by an isolated electronic terminal 61E in alternators with a multifunction controller. The task of this terminal is, on the one hand, to activate the battery charge indicator lamp and, on the other hand, to indicate to the various loads that the alternator is in charge mode.
The battery charge indicator lamp itself is supplied via terminal 15 from the instrument cluster. It comes on when the voltage at terminal 61E is below 1.5 V. The battery charge indicator lamp goes out when the voltage at terminal 61E is above 8 V.
Alternators with a multifunction controller can be recognized by the plug connection of terminal 61E. As a result, the 6 mm threaded stud has been dispensed with.
The indicator lamp lights up when:
Ignition on with engine stationary, alternator does not charge, failure of belt drive, interruption in excitation, controller overvoltage, break in charging cable
The second cable in the plug connection at the alternator is terminal 15 that serves as a reference signal for determining whether the alternator is charging.

[TerminatorX5]

Alternator Voltage Regulator

The rectified voltage generated by the alternator depends on the electrical load and the engine speed. A regulator system is required in order to supply the electrical loads with a constant voltage. The alternator voltage is normally controlled to values between 13.5 V and 14.5 V. Large changes in the current load of the alternator (major loads cutting in or out) can cause the voltage to temporary deviate from this range. These swings, however, must not exceed 1 s.

[TerminatorX5]

Load Response Function, Alternator Voltage Regulator

The alternator current changes abruptly by switching major loads. This load results in engine speed fluctuations when the engine is running at idle speed or at low speeds. In order to prevent this disturbance the load response function of the alternator limits the power increase at low engine speeds as engine operation is particularly susceptible to disturbances at these low speeds. The current increases at a rate of approx. 10 A per second at engine speeds below 1000 rpm. An unavoidable side effect of this function is fluctuations in the brightness of the headlights at idle speed.
The load response function is not active at medium and high engine speeds.
Fluctuations in the brightness of the headlights at engine speeds above 1000 rpm are an indication of a faulty voltage regulator.

[TerminatorX5]

Alternator and Battery Wiring

Due to the alternator and battery electrical connections shaking loose or corroding the resulting contact resistance can be so high that the battery is no longer charged sufficiently. These conditions can also occur only intermittently. Simple visual inspection is generally not sufficient. Particular attention should be paid to the ground connection of the engine and body.
It is possible that the fault may be dependent on load as the engine can move within certain limits thus mainly affecting the connections in the engine compartment.

[bdriven]

Wow ! Great info ! Thank you Term! will keep an eye on it and let you guys know !