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W is for wiring from the windings


istruggle2gate11
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Recently, my new found wading antics has been killing off alternators at an alarming rate (wading damage is a massive downside to megasquirt!)

Anyhoo, down to my last spare alternator of the right hand and of half decent amperage, its a 70 amp lucas doo daa but hasnt got a W terminal for sending an RPM signal. Whilst Im not fussed about the rev counter working, my LPG system uses the RPM to switch over at 1500rpm on cold start, so I really wanted it.

A quick call to FridgeFreezer, seeing how I could use the spare channel on my MSnS, he mooted that the W terminal is just a wire from one of the field windings.

So, back of the alternator off, a quick solder to a winding - bingo - one W wire, rev counter and LPG as happy as can be (before they meet Mr. Deep Water again!).

Cheers Pal.

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Rog,

Alternators are a 3 phase device ......................the phases are normally nomenclatured as 'U' , 'V', & 'W' ...............

So I guess you could have a U, V, or W terminal :lol: ........................ but it matters not...............the output will provide one complete cycle per revolution ............. hence the W terminal is often referred to as the 'speed' terminal...........

gallery_269_31_12097.jpg

Its sad .............I really need to get out more ............. :rolleyes:

:)

Ian

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'tis indeed.

Older alternators will produce a sine wave, the last few i've looked at have produced much more of a square wave, i presume this is due to the shape of the windings, i don't think there's anything else in there to shape the wave.

[homer simpson]

:blink:

I like donoughts

:blink:

[/homer simpson]

Does this effect the readings required by said RPM and LPG?

I can see me bringing out a lot of old alternators from retirement now!

Rog,

Alternators are a 3 phase device ......................the phases are normally nomenclatured as 'U' , 'V', & 'W' ...............

So I guess you could have a U, V, or W terminal :lol: ........................ but it matters not...............the output will provide one complete cycle per revolution ............. hence the W terminal is often referred to as the 'speed' terminal...........

gallery_269_31_12097.jpg

Its sad .............I really need to get out more ............. :rolleyes:

:)

Ian

That actually helped mate, ta, I nearly kind of understand.

Mods - for mere mortals like me, the info above would be good in the tech archive?

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Rog,

Alternators rarely die from a terminal illness after wading …………………its just that muddy water is unfriendly to the alternator internals ;)

Most of the problems are due to brushes seizing, dirty slip rings and corroded terminals (like those that go off to the voltage Reg) ………….often a good strip down and rebuild will make them as good as new.

Front and rear bearings can be sourced from BSL…………

:)

Ian

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What he said ^^^ my dad never cleans his alt after off-roading and as a result it's stopped working about 5 times, but each time I unscrew the brush pack, a bit of WD40 and some wiggling and the brushes un-seize and it works again. It's a cheeky fault as the thing doesn't charge, but the battery light goes out OK so it took a bit of looking first time to work it out ;)

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A neighbor gave me a couple of tachometers from wrecked Freightliners. To use in my SIII, I added a connecing wire to one of the stator windings. My alternator is a Delco-Remy so no soldering required.

When I had the alternator apart, I noted the number of poles on the rotor and the diameter of the alternator and engine pullys, so I could calibrate the tachometer to my engine with the dip switches on the tachs.

After I had the tach working, I made a temp mount, but it was too shaky so I had to modify the dash a little.

Delco-Remy - SI10 - 61amps

post-208-1188911888_thumb.jpg

Calibration Set-up - This tach only reads to 3000, so I used the one below, reads to 3500.

post-208-1188912038_thumb.jpg

Temp Installation

post-208-1188911951_thumb.jpg

Modified Dash

post-208-1188912084_thumb.jpg

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'tis indeed.

Older alternators will produce a sine wave, the last few i've looked at have produced much more of a square wave, i presume this is due to the shape of the windings, i don't think there's anything else in there to shape the wave.

Just thinking, if the rotor magnets were saturated, at maximun excitation current, might clip the tops of the sine wave. Or a gated SCR will clip the wave but I don't think they are used in small alternators/voltage regulators.

[homer simpson]

:blink:

I like donoughts

:blink:

[/homer simpson]

Does this effect the readings required by said RPM and LPG?

I can see me bringing out a lot of old alternators from retirement now!

That actually helped mate, ta, I nearly kind of understand.

Mods - for mere mortals like me, the info above would be good in the tech archive?

This should not affect the frequency of the sine wave, only the maximun voltage. I think, it has been a long time since I was in school. The rpm of the rotor will determine the frequency of the sine wave, the amount of excitation current applied to the rotor will determine the peak voltage of the sine wave.

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Rog,

Alternators rarely die from a terminal illness after wading …………………its just that muddy water is unfriendly to the alternator internals ;)

Most of the problems are due to brushes seizing, dirty slip rings and corroded terminals (like those that go off to the voltage Reg) ………….often a good strip down and rebuild will make them as good as new.

Front and rear bearings can be sourced from BSL…………

:)

Ian

So I have been informed, Ive got four good ones all ready for rebuild now, just got my ass to Leicester to get them done.

I did clean out the latest failed unit (really like that one as its a 120amp unit, put it back on, and rather than running around to the dash and seeing if the battery light went out and or started flickering whilst running, I put a multimeter across the battery terminals, struck the motor up, light went out, went to the front and looked at the reading 14.2v = happy days.

Sat back, having a brew, quite happy at my reclaiming efforts, then noticed the voltage increase gradually, it went from 14.2v to 16.3v at which point I bottled it and turned it off.

Is this the regulator thats gone?

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Yup, and it's easily replacable if its got the regulator/brush pack on the back.

In terms of sine and square waves, the LPG system probably works on the leading or trailing edge of the wave, so it won't make any (hardly) difference.

Yes mate, looked at your post in the tech archive, where did you buy the regulator from? What price should I be looking at?

The one I have is similar, just have to remove the rear cover to get to it.

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  • 1 year later...

Hi, sorry to drag up an old thread, but my question is related.

I want to install a tachometer to my 200tdi, what tachometer should i use?

also will my 200tdi standard alt have the W terminal/spade connection?

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