Off the car Alternator test?

[tolsen]

Re: Off the car Alternator test?

Mad smart person, let me know the full VIN of your car and I'll look on EPC to see if it needs a diode lead.

After a good while staring at the EPC it would seem that the:
diesel 450 does have a diode lead
700cc 450 doesn't
Roadster doesn't
600cc 450 some do, some don't



But that wouldn't explain why it doesn't charge when the diode breaks down. If it is there to protect the ECU then the ECU would have no other way to detect a surge or high voltage as it's relying on the diode to protect it. If it has no detection then it wouldn't know if the diode was faulty or not. The ECU would still output the exciter voltage so the alternator would still charge.

The diode lead is just a short lead that connects from the alternator to the car body earth from what I remember reading on another thread.

I'm not doubting you, just trying to justify how it all works and what it's for.

The alternator in my 2002 Cabrio Cdi is conventional with only B+ and D+ terminals.

A failed zener diode lead usually conducts both ways, just like a wire, so alternator does not get excited and no longer charging battery. Does this not explain why an alternator with a failed diode lead does not charge?

I doubt ECU gets involved with voltage regulation. Charge light on instrumentation has a wee resistor in parallel. This means alternator will charge even when charge light bulb is burnt out.

[Jan Rune]

Re: Off the car Alternator test?

I have always been under the impression that the alternator is like a constant current source, the voltage can vary and is therefore not suitable for direct connection to the battery. The zener is there to clamp the voltage to a safe voltage for the battery.

So when it fails(shorted), it wont let the current flow.

On the other hand i have never seen a diode lead. So i might be wrong!

[Evilution]

Re: Off the car Alternator test?

A failed zener diode lead usually conducts both ways, just like a wire, so alternator does not get excited and no longer charging battery.

So, the diode lead connects to the same alternator pole as the exciter wire and the other end goes to earth? So when the diode breaks down, the exciter voltage travels the path of least resistance and goes straight to earth instead of passing through the alternator and exciting the coil?

Charge light on instrumentation has a wee resistor in parallel. This means alternator will charge even when charge light bulb is burnt out.

That bit i do understand, seems odd that they'd run it through the ECU and then need to use the diode lead to protect it. Surely a plain wire from the ignition, light and resistor in parallel and straight into the alternator.

Working on that assumption, disconnecting the diode lead would allow the alternator to charge again (for short term testing purposes obviously) and replacing the ECU wire with a more standard setup would be a safer option.

[tolsen]

Re: Off the car Alternator test?

So, the diode lead connects to the same alternator pole as the exciter wire and the other end goes to earth? So when the diode breaks down, the exciter voltage travels the path of least resistance and goes straight to earth instead of passing through the alternator and exciting the coil?

That is my understanding of how the diode lead works.

We still need to fathom out what the mysterious PHIN terminal is. Perhaps someone in possession of a spare or fubared alternator can open it out. I am aching to learn how the PHIN terminal is wired internally on the alternator.

[Evilution]

Re: Off the car Alternator test?

Well, it seems to me that the PHIN terminal is exactly the same as the D+ terminal. Voltage in to excite the coil.
I have 2 fubared 700 alternators.

[Mad smart person]

Re: Off the car Alternator test?

Greetings All, just wondering if anyone has a known GOOD alternator they could clamp in the vice and connect up as described, to see if the 'test' bench procedure works on a Smart alternator. Me is wondering if these Smart alternators are 'too' smart, ie the little electrical 'buggery' box attached to them, needs to be given some digital signal, along the DC, phin in line?? I don't have a VIN number for the car, so am unable to help there, as to the diode line or not. As far as I know the engine was exchanged for a dead engine not a faulty alternator. I didn't get to hear or see the engine working before being swapped out. This hole is getting deeper.
Cheers, Ian.

[tolsen]

Re: Off the car Alternator test?

Well, it seems to me that the PHIN terminal is exactly the same as the D+ terminal. Voltage in to excite the coil.
I have 2 fubared 700 alternators.

I think PHIN is for external voltage sensing so regulator can adjust voltage more accurately according to load. My two lead alternator is machine sensing meaning regulator senses voltage at the alternator. Actual voltage at ECU or at starter battery will always be less than voltage at alternator.

[Mr_J_P]

Re: Off the car Alternator test?

Are you 100% sure the roadster doesn't have a diode lead? That would save me a lot of time

Mad smart person, let me know the full VIN of your car and I'll look on EPC to see if it needs a diode lead.

After a good while staring at the EPC it would seem that the:
diesel 450 does have a diode lead
700cc 450 doesn't
Roadster doesn't
600cc 450 some do, some don't



But that wouldn't explain why it doesn't charge when the diode breaks down. If it is there to protect the ECU then the ECU would have no other way to detect a surge or high voltage as it's relying on the diode to protect it. If it has no detection then it wouldn't know if the diode was faulty or not. The ECU would still output the exciter voltage so the alternator would still charge.

The diode lead is just a short lead that connects from the alternator to the car body earth from what I remember reading on another thread.

I'm not doubting you, just trying to justify how it all works and what it's for.

[tolsen]

Re: Off the car Alternator test?

Are you 100% sure the roadster doesn't have a diode lead? That would save me a lot of time

There is one sure way to find out - look!

[themadsparkie]

Re: Off the car Alternator test?

Hi,

I recently solved a problems for a Mercedes specialist that had strange issues with a smart emanating from a diode lead,

For reference the part is a 1500 Watt MOSORB® Zener Transient Voltage supressor, see the data sheet:

http://www.onsemi.com/PowerSolutions/product.do?id=1N6290A

I found out after reading the part numbers from another vehicle:

1.5KE62A or 1N6290A.

The PHin on the alternator is there to excite the regulator / field windings to kick the alternator in as stated in other posts from pin 47 of the ecu.


Though this may be useful reference.

Regards Themadsparkie

[ethanol-smart]

Re: Off the car Alternator test?

OH, this was a very interesting but confusing thread!

I found it when I looked after how to fix my lit charging light.
I have a 450 Mk2 with gasoline engine. Earlier this week, the car as usual worked perfect to job and also started nice for going back home in the afternoon.
But after some seconds, or maybe all time, the charging light was now on.
I tried to re-start, but still the charging light refused to stop lightning.
So I decided to hope for the best and turned off all lights and drove home. I made it all about 50km and it could even be started in safety at home, but the battery was real low now.

I charged it over the night and this weekend I wanted to fix this. Started engine without problem.
But now the charging light is coming off as it should! I measured the battery voltage during engine running, and it was the normal 14-14.5V so the alternator is obviously workning perfect right now.
However, from my earlier experience, I know that such warnings should not be ignored, the alternator is probably having some problem.
In 95% of the cases I have seen, an alternator of the age of more than 80000km (mine is about 90000 km) can and will be with worn out slipring-contacts (those spring loaded antrazhite pieces who are transfering the magnetization current needed to get the charging started in the alternator).

Now I only wanted to jack up the car and find out what regulator/coal keeper I need in order to get it and mount it.
(On all cars I worked on so far alwas had integrated regulator and coal-keeper, except the oldest ones from about before 1975, where the regulator is mounted separately somewhere in the engine bay)
The fault is normally in worn out, and therefore too short, coals, but can sometimes also sit in the electronics of the built in charging regulator.
Thats why there are cheap spare replacements for almost any car in any spare part shop.

But...
In this thread I dont see anything mentioned about the regulator or the slipring coles.
Is it a separate regulator in the Smart? Or it is not known and maybe this often mentioned diod is doing the regulator job?
How about the slipring coles, are they possible to change?
Someone have dismantled the Smart generator? Smart generators seems to be a lot of mysticism...

I find it very stupid if such known-to-fail-sooner-or-later component as the slipring coals/regulator, are impossible to replace on the Smart alternator (in place in the car even).
Is this really the case?
Also this small fault would have to lead to a total change of the alternator, which in turn is so tightly mounted the only child hands could work with it normally...

I understand that the alternator is supplied form Nippon-Denso, someone have any documentation from them?

For now, I probably will put back the protection of the alternator and hope for the best, even if its against my insticts...

Any info in this matter is highly appreciated!

[ethanol-smart]

Re: Off the car Alternator test?

There is one sure way to find out - look!

Where to look..?

[tolsen]

Re: Off the car Alternator test?

As you say it is advisable to open out that alternator with view to inspect and renew brushes and possible the whole regulator module if it can be sourced. Perhaps bearings as well when you are at it.
I have overhauled the Bosch alternator fitted in my Cdi. Had to do it as it was seized solid following a lengthy lay-up. The alternators fitted in Smarts are all standard and no different to any other alternator.

Sorry, have no photo of brushes and regulator assembly.

[ethanol-smart]

Re: Off the car Alternator test?

Now we're talkin, Tolsen!!
I was just into write u in another thread about your restorations of this alternator...
However, i understand that the one U worked on is a Bosch for a CDI-Smart, whereas I have a Nippondenso- altern. in my gasoline mk2.

However is it possible that no-one have done the same job on that alternator??
Its so simple on normal cars to replace the contacts and regulator, a real std-job!

[ethanol-smart]

Re: Off the car Alternator test?

For further reference, I found a Lucas repacement for the 0.6 non AC 1998-2004

http://www.lucasee.com/frisoeg.php?type=ombytning&nr=LRA02345&menu=omb&tt=gen

LRA02345, 12 Volt, Int. Regulator
EXCHANGE ALTERNATOR 75A SMART
Crosss no:
0002801V002
0003250V007
0003250V008
1601540101
1601540201
63341896
A1601540101
A1601540201
MAN1170

And here are some more partnumber:

http://www.destinationsmart.co.uk/forums/thread.cfm?threadID=518

Marelli No. 63321896,
Denso No. 0003250V008
Mercedes No. A1601540101
International No 11304 / 3 DC A1601540101, 9090173

So its a normal alternator with integrated regulator at least.

Hmmm, where can the brushes/charging regulator be sold..?