I believe this entry will be an excellent example that even simple things turn out to be not so simple. How huge is the meaning of the nuances. How complicated are the solutions used by BMW.
The short outline of these events is as follows: at the beginning of a longer trip, my E60 LCI stayed without electricity. The red battery symbol lighted up in KOMBI several times; in CCC the note “Charging fault” lighted up. After a moment, I connected INPA, and the live data indicated that the onboard voltage is around 11.0V. Obviously, the alternator is not charging. During quite a short time, the reserves of the battery were drained. Next step – tow truck and to the service. Unfortunately, this was the last working day (actually, the last hours of the day) before the Easter holidays. The only possible fast solution – purchase an alternator, available at the local warehouse. On a local warehouse was only an alternator from an “alternative” manufacturer available. List price – around EUR 360. Price with discount: 210 EUR. Evaluate the part of the profit.
One hour after arriving at the service, the new alternator was installed. I deleted all old error messages (typically: Undervoltage) and was ready for a trip.

Directly after starting the car, I connected INPA to check live data. The alternator was communicating with the DME – it was good news. My attention was drawn to the current, developed by the new alternator in idle: around 125 .. 130A! How is that possible? The capabilities of the OEM Bosch alternator are limited to 80A. A wonder alternator?
Driving out from the service box, the car almost “suffocated” two times. Ok, let’s say – the battery is practically discharged. At first sight, this symptom didn’t look noteworthy. I was wrong.
Next time, when as if not significant symptoms appeared: the cars idle was volatile, it was regularly fluctuating. Together with the idle, also the car interior lighting was fluctuating. Why so? No fluctuation and voltage instability were observed with the OEM alternator.
The first two hours of the trip succeeded without any surprises. Then, three times with an interval of approximately 2 minutes, CCC restarted. Till that, such symptoms were not observed. Coincidence? A new defect?
After two more minutes, suddenly completely everything in the interior of the car went out. KOMBI and CCC disappeared, DME turned off. After two seconds, the lightning was restored, but in KOMBI, all possible symbols were lighted up: ABS/DSC/DTC, etc. After several seconds more, the “Christmas tree” disappeared from the KOMBI.

Checking the error messages, I had to conclude that only in the DSC module is only one error message, the same – regarding Overvoltage.

As you know, the Overvoltage threshold is 18.0V. Such a voltage reached with a new alternator? It’s a terrible sign! The theoretical maximum, which could be required by DME, is 16.0V. If the voltage on the load has reached 18.0V, the voltage on the alternator’s clamps has been at least 19.0V, which means at least 3.0V above max allowed!

During the next hour, two such restarts followed. This time again, there was a forerunner – restart of the CCC, the EML icon on KOMBI lighted up, the – complete restart of the car. After restart of the car, in addition to the “Christmas tree” in the KOMBI, the message regarding faulty management of the xenon lights and that the “anti-trap” function for the windows is switched on.
Now the error message list in the DME indicated that the alternator has serious problems:

Here, the voltage, as measured by the alternator and the true one (measured by the IBS), differs for around 4.0V! It’s a huge difference! Besides, as you can see, the difference is in “both” directions, in 2 of 3 cases – 0RPM, which means the current is not flowing in the alternator path! Initially, the voltage on the clamps of the battery has increased unreasonably (according to the “thoughts” of the alternator”), later – exactly the opposite – it has dropped, not taking into account the increased required voltage. It is obvious that at this moment, the alternator has completely inaccurately measured the basic parameters! Even the “health” status, reported by the alternator itself, has been completely incorrect!

After these conclusions, it was clear that the alternator does not serve appropriately and can not be used. To get a more exact picture, how the “alternative” product “works,” it was decided to record the alternator’s live data.

I have to admit that the live data turned out even more interesting than expected.
As I have previously mentioned in the blog entries regarding this generation’s alternators: they communicate with DME via LIN (serial) interface. From DME, the commands regarding work mode are received; required voltage sent; from the alternator, instead, the data regarding temperature, the excitation winding current; developed current; internal temperature; the “health” of the alternator; its status; error messages, etc., are received.
Inspection of this alternator’s live data I will start with as if so simple parameter: temperature, reported by the alternator. What could be more simple than this? The temperature regulator should be implemented in the voltage regulator, its reading should be sent to the DME. Or even more simple – it will be enough with a temperature sensor built-in in the MCU.
Unfortunately, the temperature parameters of this alternator had nothing to do with reality. Reported temperature tended to “stuck” on 40oC, the sudden jump to 56oC, then drop to -8oC or even -16oC!

Here, after driving for several hours:

And after a second:

Additionally, here we don’t talk about any global communication problems because all other parameters remain reliable. Only the temperature data are fluctuating!
The developers of the regulator of the “alternative” alternator did not tense to measure the true temperature but have faked the data. Why is such shivering necessary? Why is it not enough to report the fixed temperature? DME regularly analyzes the data of the temperature of the alternator. DME knows what amount of heat is released in the alternator rectifier and knows the engine compartment’s temperature. Accordingly, DME can evaluate if everything is ok with the alternator’s cooling, are the data of its temperature true (reliable). If the data fluctuate in such a way, no error messages regarding the faulty parameter or plausibility are recorded. DME sees the problem, but does not understands, which error message should be recorded: temperature too low? No, it’s too high! Stop, again too low! As a result, DME does record no error messages because it’s “confused”.
Why are the temperature data critically important? When the critical temperature is reached, DME reduces the alternator’s max power for some time to protect it (its rectifier and electronics) from damage. If this protection does not work, even the most powerful rectifier will be damaged! This problem is especially topical in hot weather when the cooling of the alternator is difficult. In hot weather, when driving in the city traffic, even the E60 alternator in a perfect technical order works exactly in this mode – limited maximal power mode, because its temperature reaches over 80oC!

First conclusion – this alternator’s temperature management is not working because the data of the temperature is faked, not really measured. The alternator is not safe for use.
Let’s see the voltage data. The voltage difference between the required and measured by KL87 for the OEM alternator were close from 0.4V (low beam and additional consumers not turned on) to 1.0V (all possible consumers turned on). The situation with this “alternative” alternator was bizarre.
Here, the idle:

As you see, the required voltage 15.1V; KL87: 14.8V; drop of the voltage in wires: 0.3V (15.1 – 14.8). And here, the situation a second later:

How is that possible: required voltage 15.1V, but on KL87, it is 15.4V! There are no losses in wires, but they generate the electricity by themselves?
Of course, not! Obviously, at that moment, the alternator does not maintain the required voltage, but another – much higher!
One more parameter is worth the attention: time units, which describe how fast (easy) the alternator manages to reach the required parameters. For a correctly working alternator, this parameter is 6 in idle and drops to 0 when RPM reached 2000.
Here, the ability of this alternator to maintain the required parameters is weakened, the time parameter shivers and regularly reaches 15 units:

The confirmation for these problems can be seen in the voltage, measured by KL87:

As we see, the voltage required from the alternator is 14.6V, but the voltage, measured by KL87, is only 12.3V. At this moment the alternator does not work as it is supposed to!
Simultaneously, it sends some data of the current of excitation winding, sends fake temperature, and data that has confirmed the order to maintain the voltage of 14.6V.
Even more – not considering the as if received and confirmed command, reduced exit voltage, the alternator does not even try to fix the situation! The current of the excitation winding is only 0.5A! In a normal work mode, this parameter is at least 3 .. 5 times higher!

I believe it is not worth continuing to analyze the completely incorrect live data. Let’s move to other strangenesses (side-effects), which could be expected by such an alternator’s users.
The alternator incorrectly reports the maintained current; accordingly – the load made to the engine is calculated inaccurately. As a result, DME cannot maintain a correct idle because it can not compensate for the additional load created by the alternator.
Second peculiarity – the quality of reaching idle is significantly impaired. For example, when the accelerator pedal is released, DME can not correctly foresee the mechanical load of the engine, as a result – the idle is not reached precisely and stable, but – the idle tends to drop below 500RPM, then DME swiftly corrects the situation. Parallel to this, the alternator starts to “swing,” and it only worsens the situation. The engine almost switches off, the idle is restored by the “waves,” it is not stabilized correctly.

A short summary of the performance of this alternator:
a) the alternator does not measure the true temperature but fakes the data. The thermal management of the alternator is not realized;
b) the alternator incorrectly reports the data of the current generated by it (it indicates strongly increased values in some modes), as a result – the engine is not able to maintain idle, is not able to reach it swiftly and correctly after switching the gearbox to the N position;
c) a range of service modes are not realized in this alternator, for example, saving mode for the car electronic in case of low SOC;
d) the algorithms of alternator parameters (required voltage, etc.) are very incorrect, the voltage in even stationary modes are maintained not very precisely;
e) the management of the alternator software has very gross errors; thus, the voltage to consumers can reach even 18.0(!)V. Regular cases, when the alternator is not charging at all, are detected. The alternator can damage the electronics of the car.

And at the end – in few words, what consequences can be caused by the Overvoltage events.
Each such event can be fatal to your car. Possible damages – irreversible damages of all electronic units. Costs of repair – several thousands of EUR.
Due to the danger of this defect, I decided not to continue the trip in my car. A not expensive car from the car rental was chosen as a companion. And further thoughts, how to bring my car back “home”. And then – ASAP demounting of the product, called the “alternator” by its manufacturer, and the OEM alternator installation.

Why has such a situation appeared?
For several times I have raised the question – communication of the DME with the alternator is “know-how” of the manufacturer (BMW). The nuances of the data exchange protocol are a carefully kept secret. Without any slightest doubt, the alternative “alternator” developers haven’t succeeded in deciphering this protocol. Yes, the basic data is if give some readings, at least one basic parameter is faked, but… The sublet nuances have not been conquered.
These “products” can work only on cars, which already were in a poor state before installing the “alternator”. For such cars; the vibrations; fluctuating idle; CCC restarts, and error messages in all blocks are a common thing. But for the car owners, who maintain a good technical condition of their vehicles, I categorically suggest avoiding such non-OEM “products.”