Technical Alternator only starts generating after revving

[koalar]

While cranking
Did you disable engine starting

There's normally a delay in the reading with a multimeter

I take it you clean the slip rings up

With the new regulator, before you took it out, was it 50 ohms, has something gone short internally?

Main thing is working

 

[g8rpi]

As JackWhoo mentioned the alternating starting on revving is at least partly due to residual magnetism. This can change with every on/off cycle. Thus the current "fix" may not be relible. The old dynamos relied on residual magnetism to work. You could reverse the polarity of the system by reversing the residual magnetism. This was called "flashing the field" because it generally caused a flash as you connected the field terminal directly to the battery....
On 30mA, the "start-up" current will not be supplied directly from a microprocessor output. Apart from the current limitation they are not tolerant of 14V plus spikes from a car supply. Yis I'm aware that you can connect a PIC pin to the mains via a resistor for zero-crossong detection. The input protection diodes clamp the voltage close to the supply rails. But that is very low input current and does not supply current from the pin.
As an example the Fiat Croma BCM supplies current to the fuel tank sender at a lot lower current. A microprocessor input (ADC) measures the voltage developed across the sender resistance. The energising current is provided by a separate circuit, not the microprocessor. It uses a transistor. I know this because I repaired the BCM on my Croma by replacing the transistor.

Robert.

 

[jackwhoo]

12V Electronic Buzzer with Flying Leads

Panel mount electronic buzzer with flying leads.Operating voltage: 12VRated current: 25mASound output @ 20cm: 75dBFrequency: 400±100HzMounting Hole Pitch: 27.5mm2mm diameter mounting holes

www.switchelectronics.co.uk

Use one of those in addition to a filliment warning bulb and never miss a no charge event again.

Then all that's left is some type of physical vibrating warning- something like an aircraft stick shaker.

Or a pyrotechnic signal.

 

[nigelvan]

Back to square one. I just started this morning and I had the original symptoms, slightly had to raise the rpm to get the alternator going.
Yesterday I did multiple engine starts and a test drive, everything was fine.

@koalar no I did not disable engine starting nor did I clean the slip rings.

At least I now know it's not starting on residual magnetism.
Maybe it's time for a new alternator after all

 

[koalar]

Personally I doubt there anything wrong with the body computer, it pumps out 10V at ignition on D+ disconnect

It's supposed to pulled down to 1V which it is does

It very rare for BSI to fail, even rarer to one day work or another day not

When it's charging what volts do you have at D+

Here's my working alternator, car just started at idle

Unfortunately the replacement regulator gave different symptoms and results, if it was the same we would have known to look elsewhere


The alternator should detect when it starts to spin and wake itself up

Here's a typical alternator IC but not yours, circuit diagram with the same LCR and active lamp circuit

 

[jackwhoo]

The alternator needs a little help to start at low revs which is why there is a current limited supply to the L terminal. The current limited supply starts the rotor electro magnet.

 

[jackwhoo]

To add to the mix dumb alternators have a cut in rpm speed at which they start to operate.
Even with help from current to the L terminal if the cut in rpm is not reached the alternator will not produce power and the charge light will remain on.

 

[nigelvan]

D+ stable at 14.6v
B+ also stable at about 14v, tested at different rpms and loads
I'm going to look for another regulator and send this one back as faulty.

 

[jackwhoo]

Hi , I have tried to keep up with what is going on please forgive the following questions.

If you wire a low watt bulb from battery + to the L terminal how does it behave under following conditions;

Engine not running?

Engine started?

Engine started and rpms raised?

Plus can the wire from the BCM power a small watt bulb ?

Best wishes

Jack

Il

 

[g8rpi]

Nigelvan, Why do you think it is not residual magnetic field allowing the alternator to start?
Residual magnetic field would account for the inconsistent operation as it can change every time the alternator is started / stopped.
I'm a bit frustrated by constant mentioning of "computer" control of the alternator and the like. From the OP's photo of the original regulator the BOSCH part number is F00M144128. This is a "dumb" alternator regulator with "L" and "FR" terminals. L is lamp and is just like the classic alternator and is connected to the switched ignition supply classically vis a filament lamp but may be supplied via a switch (can be electronic in a control unit) to turn the alternator off. The FR terminal provides an (optional) indication TO a control unit to indicate how hard the REGULATOR is working. This is dependent on load current and shaft speed. High current and high speed results in low regulator output and FR voltage. Low speed and even medium current results in high output. If the FR voltage is high the ECU can increase engine revs to compensate.
All an ECU can do with this type of regulator is turn the alternator off (to save fuel) or increase revs to keep the alternator working efficently.
I'm as sure as I can be, without actually seeing the vehicle, that the BCM is not supplying enough current to the L terminal.
Full fix - new BCM, acceptable fix - add "Alternator warning" light connected to the L terminal leaving any connections to BCM ECM intact.

 

[Communicator]

Well guys, I refitted the old regulator because I rather have to rev the engine than have nothing at all, first glued it back together with epoxy because I opened it.
It now just works... I just started 3 times in a row and the alternator fired right up.
The voltage at the connected d+ is back to 0,7V also while cranking. current draw 34mA with ignition on and while cranking.

My girlfriend just told me I look 'puzzled'..

Must be magic.

 

[nigelvan]

Nigelvan, Why do you think it is not residual magnetic field allowing the alternator to start?
Residual magnetic field would account for the inconsistent operation as it can change every time the alternator is started / stopped.
I'm a bit frustrated by constant mentioning of "computer" control of the alternator and the like. From the OP's photo of the original regulator the BOSCH part number is F00M144128. This is a "dumb" alternator regulator with "L" and "FR" terminals. L is lamp and is just like the classic alternator and is connected to the switched ignition supply classically vis a filament lamp but may be supplied via a switch (can be electronic in a control unit) to turn the alternator off. The FR terminal provides an (optional) indication TO a control unit to indicate how hard the REGULATOR is working. This is dependent on load current and shaft speed. High current and high speed results in low regulator output and FR voltage. Low speed and even medium current results in high output. If the FR voltage is high the ECU can increase engine revs to compensate.
All an ECU can do with this type of regulator is turn the alternator off (to save fuel) or increase revs to keep the alternator working efficently.
I'm as sure as I can be, without actually seeing the vehicle, that the BCM is not supplying enough current to the L terminal.
Full fix - new BCM, acceptable fix - add "Alternator warning" light connected to the L terminal leaving any connections to BCM ECM intact.

Because we have the situation with the old regulator:
- Alternator will not start at 700 rpm, will start at about 1500 rpm, no charge warning light on
- this is conistent, I've been driving like this for the past year or so... I just found it annoying with the increasing rpm at idle

New regulator, which behaves differently:
- alternator will not start at 700 rpm not on 1500, not at 3000 rpm...
- will start when fed through a bulb, but the current readings were not consistent, min 250mA, max 700mA.
- immediate charge warning light on after starting the engine

Current from BCM is consistent in both cases. When it was briefly working yesterday afternoon the current stayed the same as previous tests, about 30mA.

If the situation with the new regulator would be the same as with the old one then I would fully agree with you.

 

[jackwhoo]

Please clarify if your last post referring to charge light , is the charge light the one driven by the suspect BCM?

 

[nigelvan]

Hi , I have tried to keep up with what is going on please forgive the following questions.

If you wire a low watt bulb from battery + to the L terminal how does it behave under following conditions;

Engine not running?

Engine started?

Engine started and rpms raised?

Plus can the wire from the BCM power a small watt bulb ?

Best wishes

Jack

Il

engine not running: bulb on, draws power

engine started: bulb starts alternator, bulb will go out

Engine started and rpms raised: keeps working, once alternator is started it keeps on working

No, the BCM cannot power the lamp, the BCM only puts out 30mA before decreasing the voltage

 

[jackwhoo]

engine not running: bulb on, draws power

engine started: bulb starts alternator, bulb will go out

Engine started and rpms raised: keeps working, once alternator is started it keeps on working

No, the BCM cannot power the lamp, the BCM only puts out 30mA before decreasing the voltage

Hi ,

Which voltage regulator fitted for the above?

What rpms required to turn bulb out?

Thank you for your continuing updates.

By the way you can bench test alternators with a simple circuit , 12v vehicle battery , and electric drill (mains power for speed)

J

 

[g8rpi]

Because we have the situation with the old regulator:
- Alternator will not start at 700 rpm, will start at about 1500 rpm, no charge warning light on
- this is conistent, I've been driving like this for the past year or so... I just found it annoying with the increasing rpm at idle

New regulator, which behaves differently:
- alternator will not start at 700 rpm not on 1500, not at 3000 rpm...
- will start when fed through a bulb, but the current readings were not consistent, min 250mA, max 700mA.
- immediate charge warning light on after starting the engine

Current from BCM is consistent in both cases. When it was briefly working yesterday afternoon the current stayed the same as previous tests, about 30mA.

If the situation with the new regulator would be the same as with the old one then I would fully agree with you.

But, you previously said "I couldn't find the exact same one for Bosch but I ordered one from Hitachi. It should be compatitble. At least it looks the same and has the same voltage rating."
So there is a possibility that the new regulator is not correct for the vehicle. Do you have details and or pictures of the new regulator?

 

[jackwhoo]

Currently (ha ha) a lot of variables have been introduced in original voltage reg opened, second voltage reg suspect as direct replacement for original- not your fault lots of cross references are poor or just wrong.

 

[nigelvan]

But, you previously said "I couldn't find the exact same one for Bosch but I ordered one from Hitachi. It should be compatitble. At least it looks the same and has the same voltage rating."
So there is a possibility that the new regulator is not correct for the vehicle. Do you have details and or pictures of the new regulator?

F00M144128 is the original one
Hitachi 130570 is the new one should be the equivalent according to multiple car part sites. I dug a bit deeper and it should be compatible with

• BOSCH: 1986AE0124, F00M144126

F00M144128 replaced F00M144126
So, yes, it should work.
At least I expect the same symptoms if the regulator was not at fault.

But, good news, I just found the exact same one on the jungle site. So when I order that one we can rule out the incompatible/defective new reg.

 

[nigelvan]

50 ohms isn't right. 1.35K is correct ish

It's unlikely going to start with the body control now

What's the part number of the regulator fitted


You original regulator should be lamp protect

But not all are but look similar for example F 00M 145 328

Description​

Specs 12 Volt, B-Circuit, L(RC)- F(FR) Terminals, 13.8 Default Vset For Bosch IR/IF Alternators Notes: *Vset controlled by vehicle RVC system. Without choke drive. L(RC) terminal is computer RVC(PWM) connection, not Lamp Regulator damage if tested as Lamp connection


If you are measuring direct on alternator pin and case there's only the new regulator module with any resistance between these points

Where did you find this information? I'm trying to find datasheets/specs of the all the different regulators but I can't find much between all the webshops besides voltage rating.
Anyway I just ordered the same regulator as the original one, I missed it before but it's available on Amazon. Going to take some time though to get here.

 

[jackwhoo]

No, the BCM cannot power the lamp, the BCM only puts out 30mA before decreasing the voltage
[/QUOTE]


To me this indicates BCM fault or wiring from BCM to L terminal

If BCM can't power a small bulb it is clear it can't power the rotor electro magnet.

We will know more when you receive correct regulator.