Alternator brush pack / regulator types & part numbers

[ghost123uk]

Just to add to the conversation =

I ended up buying the 14 volt, £20 one from Europarts AND a 14.5 volt, £12.50 one from ebay (as per my links above ^^^) They were both "Topran" items, big price difference !

I did a quick "before" test = 13.6 volts. I fitted the 14.5 volt £12.50 one and again tested the volts = 13.3 Drove it around a bit = no change

Took the bedding and cushions out again and fitted the 14 volt £20 one and lo and behold = 14 volts. A bit annoying though as I really wanted 14.2 or even 14.4.

I suppose I will send the ebay one back for replacement and see what the new one does, all a lot of faff though The supplier of the duff one won't pay for all the faff either.

And what if I was a non techie type, had the duff one fitted, set off for a weekend away, in the depth of winter, broken down with a flat battery up on the N Yorkshire moors at 2 am with no mobile phone. One could die then, and would they pay you for the inconvenience = NO



Interestingly, during testing, I confirmed summat I suspected. When I first start the engine, the multimeter reading rises slightly during the first minute or so by about 1 volt. I mentioned this on another thread (in answer to someone's question about voltages) and I think it was Martin who pointed out that the reading should be steady at ~14 volts right away. He is correct in theory, and the voltage at the Alternators output was instant, but even with good connections, it seems there is some slight resistance present in the cable, enough to induce a voltage drop as the battery draws relatively high current, recovering from the initial drain by the starter motor. None of this is important, just "of minor interest" (to some )

p.s. = Sorry, I started a sentence with "And" up there

[bigherb]

Interestingly, during testing, I confirmed summat I suspected. When I first start the engine, the multimeter reading rises slightly during the first minute or so by about 1 volt. I mentioned this on another thread (in answer to someone's question about voltages) and I think it was Martin who pointed out that the reading should be steady at ~14 volts right away. He is correct in theory, and the voltage at the Alternators output was instant, but even with good connections, it seems there is some slight resistance present in the cable, enough to induce a voltage drop as the battery draws relatively high current, recovering from the initial drain by the starter motor. None of this is important, just "of minor interest" (to some )

p.s. = Sorry, I started a sentence with "And" up there

That's how the alternator works. These are machine sensed alternators the only way the alternator knows how much to charge is by comparing the output terminal voltage to the regulator set voltage. The lower the output terminal voltage the more it increases the the field windings current to increase the output to reach the set voltage. In theory it always runs at the set voltage but in practice it will run about 1-1.5 volt lower when on high output.
If you have a twin trace oscilloscope using an amp clamp on one trace and volts on the other you can get a good relationship between output current and volts.
At this time of year you can get some interesting readings on how the battery accepts a charge when it is cold before the electrolyte warms up.
When checking the alternator output voltage readings in isolation gives you a rough idea if it is working or not. But you also need the current readings for a full understanding on what the alternator is doing.

[California Dreamin]

Interestingly, during testing, I confirmed summat I suspected. When I first start the engine, the multimeter reading rises slightly during the first minute or so by about 1 volt. I mentioned this on another thread (in answer to someone's question about voltages) and I think it was Martin who pointed out that the reading should be steady at ~14 volts right away. He is correct in theory, and the voltage at the Alternators output was instant, but even with good connections, it seems there is some slight resistance present in the cable, enough to induce a voltage drop as the battery draws relatively high current, recovering from the initial drain by the starter motor. None of this is important, just "of minor interest" (to some )

p.s. = Sorry, I started a sentence with "And" up there

That's how the alternator works. These are machine sensed alternators the only way the alternator knows how much to charge is by comparing the output terminal voltage to the regulator set voltage. The lower the output terminal voltage the more it increases the the field windings current to increase the output to reach the set voltage.

Now I know you didn't mean to write 'Field Windindings' so as a point of correction, it is the variation in power to the 'Rotor windings' and the strength of the magnetic field this produces that increases/decreases alternator output (controlled by the voltage regulator)
Current is induced in the fixed field, or as they are more often called, 'stator windings'.

Sorry for the correction but as you were making a technical point I thought it needed to be clear.

Martin

[ghost123uk]

When I first start the engine, the multimeter reading [at the battery terminal] rises slightly during the first minute or so by about 1 volt.... the voltage at the Alternators output [14 volts] was instant.

[So] even with good connections, it seems there is some slight resistance present in the cable, enough to induce a voltage drop as the battery draws relatively high current, recovering from the initial drain by the starter motor.

I suppose, using Ohms law, and if one measured the current flowing during that first few seconds, one could calculate the resistance of the alternator to battery circuit. My guess would be maybe 1/4 Ohm ?

Off outside now to...



pull out some dead plants in the garden

[1664]

Thanks Martin - I have no idea the size of my slip rings (or alternator). I need to have a look at some point......

[ghost123uk]

Thanks Martin - I have no idea the size of my slip rings (or alternator). I need to have a look at some point......

I didn't pay any attention to this aspect when I ordered mine (as in links above) and on the Euro parts page there is no mention of 28mm ones I suppose, if the number is still legible on the alternator, one could look it up = more faffing around !

Also, the specs for the Europarts "Topran" ones says 14.5 volts but the one that arrived had 14 volts on it and produces 14 volts (I really wanted 14.5 volts).

All this faffing around, this shouldn't be this complicated

[California Dreamin]

Indeed...there are two sizes as indicated, for 28 & 32mm diameter slip rings.
Think of it this way....use 28mm part on a 32mm slip ring alternator and the brush holder might touch the slip ring which could result in brushes jamming into their holder.
On the other hand: fit a 32mm part to 28mm slip ring rotor and there will be excess brush lateral movement as the gap will be rather large. This may also result in the brushes falling out when they are only part worn.

I suppose you might just get a pair of jaws in there from a vernier to determine which you have (on an unworn part obviously).
Martin

[bigherb]

Now I know you didn't mean to write 'Field Windindings' so as a point of correction, it is the variation in power to the 'Rotor windings' and the strength of the magnetic field this produces that increases/decreases alternator output (controlled by the voltage regulator)
Current is induced in the fixed field, or as they are more often called, 'stator windings'.

Sorry for the correction but as you were making a technical point I thought it needed to be clear.

Martin

I did mean to write field windings they are actually the rotor windings. Well Lucas seemed to think so.

[California Dreamin]

You are right of course, rotor and field windings are indeed one in the same.



My apologies.



Martin

[Oldiebut goodie]

The trouble is it makes sense either way - field windings that create the field and field windings that pick up the field!

[1664]

Right, well just to muddy the water further..... I had a look in the engine bay today and I can't see the word 'Bosch', a part number or output rating anywhere on the alternator. The only lettering is on the brush pack itself besides a sticker which says "AE Autoelectro, Bradford BD3 8TU Void if removed 131197". I've looked through all the history supplied with the van and there's no record of the alternator being replaced.

AE Autoelectro do have a website http://www.autoelectro.co.uk/" onclick="window.open(this.href);return false; but it's not much help and I doubt they'll 'remember' the van

So, my question is, where on the alternator is the manufacturer and output details? Incidentally, although the Europarts website says my van has the 90A alternator the Haynes manual only mentions 45A and 65A versions

Couple of piccies of my alternator if it's of any help........

[California Dreamin]

Looks the same as mine Bren.....So possibly 90amp although they Bosch did go to the stud connection on later 65's ......yours is an obvious refurb and the original pink? chrome sticker was probably removed when the body was cleaned. The regulator brush pack is also aftermarket so no real help their.
But I wouldn't be too worried, I think it's a pretty good bet that the one originally linked, for the 32mm slip rings, is the correct part.

Bosch went from the 'Push fit' terminal block on the 45 & early 65ah units to the much heavier 8mm stud on the late 65 & 90ah alternators....one can only conclude that they felt the 9.5mm female spade carrying the output current had reached it's design LIMIT ....afterall, checking the specs, 9.5mm terminals are rated to carry 4 to 6.0mm2 wire so 50amps max on thinwall. No wonder then that Bosch changed to the much heavier 8mm stud with eyelet on the higher output units.

Martin

[1664]

Thanks very much Martin, I'll treat it as a 90amp Bosch and get the regulator you mentioned earlier.

Wonder why the Haynes Manual only mentions 45A and 65A versions?

[California Dreamin]

I don't think the Haines took into account 'Camper Conversions', concentrating on the more common 'commercial base vehicles'. These didn't have the added electrics of a camper.
Factory convertors such as Westfalia/Holdsworth/Leisuredrive, would have had the purchasing power to order the base vans (before conversion) best suited for intended purpose. With their conversions having a second leisure battery and with split chargers or Zig units, the larger, I suspect 'optional' as I don't think they were ever fitted to a builders van, even a very late one, 90ah alternator was fitted.

When VW & other manufacturers supply commercial vehicles, it is common practice to offer a certain amount of flexibility in the base spec before going off to the coach builder. Twin alternators for instance on some Swedish and German military/Fire & Rescue vehicles....very much bespoke supply for intended purpose but not that rare an occurance for a commercial vehicle manufacturer.

Martin

[1664]

Good point, I know Autohomes must have requested certain options offered by VW as I have a padded steering wheel and rear wash/wipe amongst other things.

I'm glad it's a 90 amp jobbie makes me feel 'special'