load regulation problem

[elode]

Hello everyone, I have a voltage regulation problem. I have 13.8v at idle and when I accelerate I have 15.5v. The charging indicator lights up. My alternator seems to be working fine. Would that be the regulator? the problem is that on the sites (I am French) I find 2 regulators. One at 30€ the other at 700€?? Can anyone help me ? Thank you all.

[elode]

sorry it is 280 sL

[Vander]

You want a "Beru 90160320602", they are about $40 here in the U.S.

[elode]

for me in France it's here.
https://www.oscaro.com/regulateur-dalternateur-mercedes-benz-pagode-w113-280-sl-113-044-170-cv-288-25269-0-gt
 For my current piece it is the most expensive. Are the others the same? why this price difference?

[WRe]

Hi 
in contrast to the old ones, the new regulators are purely electronic regulators, which are now usually located directly in the alternator. I would assume that these external regulators offered here are all similar.
...WRe

[elode]

my alternator only has 3 diodes so the three-phase regulation is done afterwards I think. I rebuilt my alternator at the level of the bearings because they were worn. I noticed that the connecting wires which go to the diodes were damaged so I rewired them correctly.

[elode]

My bearing tracks were good and not worn so I reassembled with new bearings and redid the connection wiring with heat shrink tubing up to the diodes. At the alternator output I have 3 studs.
I do not understand the diagram below which does not seem to correspond to my assembly. On this one there is already the continuous alternating assembly in the alternator it seems

[elode]

What voltage should I have at the output of my 3 alternator terminals?

[WRe]

Hi, with a
1.) removed alternator, there are basically 3 things to check:
a.) Function of the diodes
b.) Function of the controller (internal or external)
c.) Charging voltage
and
2.) built-in alternator
a.) Function of the controller (internal or external)
b.) Charging voltage

The test of 1.b) and 1.c) is easier when alternator is installed.

Test

1.a) Multimeter required
The rectifier (diode plate) consists of three negative and three positive diodes, which turn the alternating voltage or three-phase voltage into something like a direct voltage. Each diode has a forward and a reverse direction. Measure each diode individually with the multimeter. If a diode does not pass in either direction or in both directions, the rectifier is broken and has probably also destroyed the regulator. The values ​​of the diodes are all comparable and If the multimeter shows voltage when testing the diode.

1.b) Adjustable power supply required, 0-15V
If you want to test a removed regulator, use a regulated power supply with at least 2A as the voltage source and connect it to D+ and D-. The rotor is replaced with a 12V/2W light bulb with a socket (an indicator insert is suitable for this). The light bulb is connected to D and DF. Mini crocodile cables are suitable as cables.
Now you can check: You increase the voltage to 12V and the light bulb becomes brighter with the voltage. We are slowly approaching 14.2V. If the control voltage is exceeded, the controller starts to work: With a mechanical controller, the lamp flashes quickly and you can clearly hear the controller rattling. The electronic controller switches the lamp off suddenly. If you lower the voltage back below the threshold value, the lamp lights up evenly. You can check the switching point with a digital voltmeter; it corresponds to the generator voltage that the controller sets.
If the bulb does not light up at 12V (and the circuit is OK), the controller is defective. Likewise if the lamp doesn't go out at 14-15V. To be on the safe side, check the circuit with a second controller.

1.c) Drive for alternator, e.g. drilling machine with appropriate spanner socket, 12V battery, test lamp and multimeter required
Be very careful when connecting the components!
Connect the battery minus to the alternator housing and plus to B+, test lamp to D+ and B+ (lamp should light up), multimeter with battery (multimter should show charging voltage of the battery, 11-13V).
Drive the alternator with the drill. The test light should turn off and the multimeter should show an increasing voltage as the speed increases, up to 14.4V.

2.a.) and 2.b)
Connect the multimeter to the battery, switch on the ignition in the vehicle, the charging indicator light should light up. Start the engine, the charging indicator light should go out. If not, then the controller or alternator is defective, if the light glows, diode are defective. The measured voltage should be between 13.4 - 14.4 both at idle and at increased speed.

I hope this helps you.
...WRe

[elode]

super thank you, in fact I am already going to test the regulator. There it is open. The transistor is ok I just tested it.

[elode]

no problem soldering no visible burnt component
on the other hand the bulb is connected to D- or d+ with df? I think d-, I prefer to ask before mistakes. thanks for your help.

[BobH]

Hello, the charge lamp is fed from the blue wire on D+, the other side of the lamp goes direct to the fuse board

[WRe]

The bulb is connected to D- with DF.

[elode]

ok thank you I ordered the Beru reference mentioned previously, I received it this evening. We will test if it is the external regulator. 25€

[BobH]

Apologies, just read the question again about connecting a temporary charge lamp for bench testing, i'll pop WRe's test procedure in the manual shortly

[elode]

Okay, quick little test done. I have a correct variation it seems. 12.8 to 13.9v. On the other hand, the control lamp no longer goes out. grrr

[mauro12]

I have similar issue as I told you before .
My voltage is jumping around from 14 to 16v at idle . Is stable with load applied ( fan and lights ) but I have very dim red light when I turn on the fan blower  . I don’t know if it’s a regulator or alternator problem . I guess mostly the regulator . I already bought a new beru and I’m waiting to install it . I’ve noticed by the way , that the new beru doesn’t have the resistor inside . It has only the 3 connectors . What difference does it make from the old bosch ? Thank you

[elode]

To solve my problem, I dismantled the alternator and desoldered the diodes which are in the previous photos. Ok for the diodes. The cables were dead so I rewired the connection cables with the diodes. A little complicated because the cables are on one side soldered with electricity and on the other with tin but you don't want to heat it too much either. To adhere to the steel of the diodes with the tin, simply sand the piece of steel otherwise the tin will not adhere.
I also checked the diodes underneath (under the board). Everything was ok. I reassembled everything and the magic, I have a stable voltage of 12v and slowly rises to 13.6v with the new regulator. My lamp goes out, it's perfect. I think I had a bad connection on the diodes with the cables.

[elode]

The tracks are in the wear ratings so we don't change. The coals were not worn out. Only the bearings were at the end of their life. Not by the number of kilometers but by age.

[elode]

the same for me, the beru does not have a transistor visible from the outside underneath. It has the same connector. Be careful when assembling, the support must be grounded to the bodywork (by the fixing) given the price you can try because you cannot kill something.
If you have a slight illumination of the lamp which amplifies when you turn on the ventilation, it is because your alternator is not able to provide the necessary power but this could also come from the regulator which is "failing". Keep us posted with the new regulator.
A new regulator won't hurt.
If your voltage changes enormously, it means that the regulator is no longer able to regulate correctly. This is the first thing. Otherwise it is a HS diode from the alternator, it is no longer the same problem because it must be changed with a new adaptable 50amp instead of the original 35amp. you have to change the connector and pay attention to the cables. Even if some strongly recommend changing the section of the wiring, you must not forget that the alternator only supplies current that the installation requires, so originally it is for 35 amp if you change to 50 amp it will be capable to provide 50 amp but you do not change your installation so the electrical wiring section is sufficient. Unless it is too old and damaged.

[mauro12]

Thank you for your replies . At idle with radio , fan blower and high beams , my multimeter shows 13.03volts . I have a very dim red light . I believe that this voltage is acceptable . If I pass 2500rpm it goes to 13.6. But the lights is still on . Something is not clear .. it stays on even if I accelerate. For sure the voltage regulator is dead but maybe some ground connections or something near the alternator . I’ve seen pagodas with no charge at idle and the red light was not on at all . This is very unclear to me .

[elode]

the operation of the red lighting is simple. If you take a 12v bulb, there is a + pole and a - pole. for the bulb to work you absolutely need the + on one side and the minus on the other. If you don't have this it doesn't work. The alternator bulb is mounted on one side on the + provided by the alternator and the + on the battery. There, it doesn't work. There is no -. If the alternator is no longer supplied: the + of it therefore changes to -. The bulb lights up. So if it lights up, it is because the alternator is no longer supplied (or the regulator is no longer regulating correctly.)

[elode]

The red alternator bulb is only an operating indicator. You can see everything. If your bulb increases in brightness if you reduce the engine speed, this is normal, the alternator no longer provides enough current, it must reduce when you accelerate. It must also increase when you "consume" more electricity in the passenger compartment. Normal because it must provide more electricity. If this is the case, it is because the alternator is producing but no longer enough, either the carbons are broken, or a diode is at the end of its life, or the track is dirty or broken.... for my case, the The alternator supplied but not in full (due to a disconnected diode) the regulator had difficulty stabilizing the voltage. Did you change the regulator? how is it looking ? normally, at idle you should be between 12.5v and 13v, high speed you should not exceed 14.4v. be careful we are talking about tension. You can have these values ​​but not have any current!!! I hope to have been clear.

[elode]

voltage is the amount of energy, current is the strength of the energy.

[mauro12]

Hi! I’ve replaced the voltage regulator with the Beru unit . The tension at idle is 14.2 very stable  and doesn’t increase when you accelerate. With everything turned on ( radio , high beam and fan blower ) the multimeter shows 13.6 volts which is quite perfect . I’ve noticed that only at night and with absolute darkness you can see a very dim red light only when you turn on the fan which I guess has the most energy requirements. Should I be concerned? Also with wipers on the tension doesn’t go below 13.4 . For me these are normal values for 60 years old car .