J1 missing 40 volts

[Al]

Right here goes; i dont do electrics so this has me foxed.

Right through 2008 bike was steadily discharging till eventually in October (morning of the muscle bike show)it wouldnt start.
Had the thing mostly apart over winter and now one piece again.
Found that one of the three phases of the alternator had come undone at its connection below the starter motor.

Good i thinks, must be fixed now.

Got it MOT'd this week and decided to do the standard checks for the ignition and charging just to check.

Manual says; 50 volts @4000 RPM when measured between any two phases of the alternator.
I've got between 8 and 10 volts.

Ohms scale resistance between any two phases is correct as per manual.

There is no continuity between any phase and earth meaning no short to earth.

Battery static voltage is about 11.5 to 12.5 volts and does rise slightly to about 13.5 volts when revved hard either with or without load.

Battery fully charged straight off the optimate is 14-15 volts.

Two possibilities exist which i cant discount.
#1 Manual says that given the above; the rotor has lost its magnetism!
#2 Could the windings of the stator be breaking down as soon as they try to charge the battery circuit?

Any thoughts much appreciated.

P.S Battery 3 year old Yuasa.
Dyna S ignition with the relay mod.
No IC ignitors.
60/55W headlight
Combined and recent regulator rectifier.
Cleaned and tightened all bullet connectors.
Re-made earths.
Overhauled starter motor.
Heavy duty starter motor hot lead.


????????

[Mick Hayward]

Hi

Check windings to earth using an insulation tester. (use the lowest possible voltage range and disconnect the alternator completely) A resistance check to earth may not show a breakdown in insulation. Any sparky should have one.

Hope this helps

Mick

[Al]

Thanks Mick. I did do a test of resistance to earth but with the multimeter which has no voltage of its own as such. Do you mean a megga?

When you say use the lowest voltage do you mean low voltage and therefore higher amperage or is that not how it works?

Usually if i think about electrics i can get them to spontaneously burst into flames without even touching them.

Been at it all day and i'm about ready to burst into flames myself!!


AL

[Mick Hayward]

Hi AL

Yes a Megger will do. If its a wind up one dont go to mad with it. It sounds like one of the windings is breaking down. A basic resistance check doesn't put any load on the winding. If you read the manual it probably says to use the highest resistance range, this gives the greatest voltage but its not a lot.

An insulation test at 250 volts will prove if the windings are sound or not.

Good luck Mick

[Al]

Thanks very much Mick. When you say 240 volts isnt that the same as mains voltage. Gives me an idea!!



AL

[Mick Hayward]

don't go there.

[Al]

Thanks again, will try to resist. Mac made a very usefull observation in a parrallel thread. I havent taken the cover off yet as was checking wires and contacts only but it looks like his rotor has come loose on the shaft and was not turning correctly!

AL

[steve bowdler]

Hi al
I am away at the moment (Its Taffus replying , I have hijacked Steves pc) and cannot check my books but when you are checking the ac output, is the alternator disconnected from the regf/rectifier?

It also worth checking is the "sense" conection to the reg/rect unit, its this wire that tells the rectifier when power is needed, from memory it alows the reg unit to short out the output from the rectifier when the main +12V(nominal) the required voltage.

Iknow you done the earths but check the reg/rect unit is earthed properly as well
Good luck
Mark

[Al]

Hi Taffus; (errrm Steve) are you on citrix?
Yes the alternator is in circuit with the reg/ rectifier for the 50 Volts check.
It is measured at the multi block connector unlike the resistance check and earth (short) check where it is isolated from the wiring.

Will have a look for the 'sense' connection. Cant say that it is immediately apparent which one that might be or for which parameter i might be checking but will also check the earthing of the regulator/ rectifier unit and if necessary, run an independent earth.

Its currently screwed to the underside of the battery box, not the best of locations or the cleanest of metal either.

Thanks for the reply. Enjoy the SW meet.


AL

[Al]

Thank you to all for your help. Probably should have done this first but i thought i had an electrical component fault rather than what i have found.

The stator and windings look very crispy and a little blackened. Some of the varnish has burnt off and i'm going to guess that this was because one of the phase wire 'bullet connectors' came undone at some point last year and it has scrapped the windings.

Also; the thin metal clamp which holds the wiring inside the alternator cover has been wearing on the outer surface of the rotor too, damaging it also.
This is definitely down to me because i thought that the two cast nipples were 'stands' for the clip,..... in fact they are to restrain it. ie clip goes behind them not rests on top.

Anyone got a good rotor and stator for sale???

Rotor is RO3 i believe and stator is three central bolt fixing.


Many thanks again for pointing me in the right direction (up the wiring or back down the wiring) you've probably saved me needlessly buying a regulator rectifier unit or battery.


AL