Author Topic: A65 6v - 12v Alternator  (Read 1621 times)

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TRIGWELL

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A65 6v - 12v Alternator
« on: 13 May, 2017, 14:21:20 »
Hi, please help………….
I’m currently building an A65 Lightning to look something like a Clubman. I have a Lightning Clubman Headlight shell which has a Central Ammeter, the Key Switch left of centre and the Light Switch to the right. I have since bought the correct wiring harness and all looks good except……..the wiring harness appears (and also my wiring diagram) appears to be 6 volt.
You can tell this by the 3 wires present in the harness for the Alternator i.e.
1) Green/Yellow
2) Black/Green
3) White/Green
A 12v Alternator on has 2 wire output.
I planned to build the bike with 12v Electrics, having bought a 12v Boyer Ignition, 6v Coils & 12v Rectifier and now find my wiring diagram ‘not very useful’ as 12v Alternators only have 2 leads off of them.
Can you clever people out there please advise on this 6v / 12v alternator issue, better still recommend a 12v wiring diagram that includes the 2 headlight switches & ammeter, along with the 2 wire output from the alternator – many thanks Ray T.

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #1 on: 13 May, 2017, 14:32:52 »
I think I found the answer a three phase alternator, but please correct me if I'm wrong - I'm certainly not 'lecky' minded!

STAR TWIN

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Re: A65 6v - 12v Alternator
« Reply #2 on: 13 May, 2017, 15:10:44 »
The important wires are the Green/black and White/Green. They go from the rectifier to the alternator. Just ignore the Green/Yellow one. That's to do with the old 6 volt system and is not required.

JulianS

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Re: A65 6v - 12v Alternator
« Reply #3 on: 13 May, 2017, 18:49:39 »
Are you using a Boyer voltage regulator? If yes just follow the wiring diagram supplied.

The pre 1966 12 volt A65 used a wiring harness with the 3 alternator connections as you describe. The green/black connecting to rectifier when light switch on headlight. The green/yellow and white/green being connected directly to the rectifier.

The 6 volt models had a similar but  different harness. The green/yellow connecting to rectifier when light switch on headlight. The green/black and white/ green being connected directly to rectifier.

The stator was the same for 6 and 12 volt the connections differed. (sometime in 1967 the 2 wire resin encapsulated stator was introduced and many bikes are now fitted with these)

For 1966 12 volt the harness was simplified and the alternator was connected for full output in all light switch positions.

If using the original type rectifier and zener diode and you have a 12 volt harness just connect the 2 alternator output wires to the respective colour wires in the harness and ignore the green/black.

If its a 6 volt harness connect green/yellow from alternator to green/black in harness and white/ green to white/green and ignore the green/yellow as Star twin advises.

Your harness will not be for a 3 phase stator, these were introduced after BSA ceased production. They can be identified by the 9 coil lamination ends visible on the inside diameter   - the single phase having 6.

What year is your bike? Should be able to find the appropriate wiring diagram and post it here.

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #4 on: 17 May, 2017, 19:15:08 »
Many thanks for the reply - I have attached a PDF of the wiring diagram I found and plan to follow.
I'm going to Kempton on Saturday and was going to bite the bullet and get new alternator & stator; as I have a new wiring diagram which expects 3 wire input I was going to opt for the 3 wire Alternator. As for the rectifier, I have purchased a £5 solid state of ebay, (seemed worth a punt at a fiver), which I have been told eliminates the zenner diode. (i do have the original rectifier and z/diode).
As I said before I'm note an electrician by any means so any advice is most welcome.   

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #5 on: 17 May, 2017, 19:20:21 »
What is the consequence of fitting a 3 phase alternator ? - ray t

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #6 on: 17 May, 2017, 20:04:58 »
As Saturday is looming fast, i will probably speak to Paul Goff. - At The moment I'm contemplating a 3 phase Alt, with an A REG 3 Rectifier/Regulator - cost is looking v. expensive though - £188 Alternator with Stator, Reg/rec another £40!. My only concern is the wire from the Reg/Rec unit back to the lighting switch - I'm sure he'll advise - ray t

STAR TWIN

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Re: A65 6v - 12v Alternator
« Reply #7 on: 18 May, 2017, 06:56:01 »
I refer the honourable gentleman to my previous post. It's the cheap (free) option and it will work. Why not try it before forking out upwards of £200?
Your bike doesn't need a 3 phase alternator. What would you be doing with all the extra wattage produced? Extra spotlights and an electric start? Heated gloves and suit (now there's an idea...). 

JulianS

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Re: A65 6v - 12v Alternator
« Reply #8 on: 18 May, 2017, 10:28:26 »
That wiring diagram is perfectly satisfactory for a 2 wire alternator. Just connect it as per the diagram.

Many owners have succesfully converted 6 volt alternator bikes to 12 volt with minimum expense.

With 12 volt you will not need wiring from regulator/rectifier back to the light switch, that part of your wiring diagram is no longer needed.

Your £5 rectifier will simply convert the alternating output of the alternator to DC for battery charging. It DOES NOT replace the zener diode which controls the charging current. You still need the zener or a Boyer powerbox or similar to control charging.

If you go 3 phase you need to reconsider the wiring circuits. Personally dont think its worth the money.

Below is from Lucas about the RM24 3 phase alternator. Just the basic charging curcuit. You could research the wiring diagrams of the mentioned Triumphs. You would need a compatible rectifier/regulator setup to handle the higher output.
« Last Edit: 18 May, 2017, 10:44:52 by JulianS »

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #9 on: 18 May, 2017, 19:36:59 »
Cheers guys - so pleased you are happy to share your knowledge - point taken regarding 3 phase Alternator and I'll be staying with the single phase option, as i plan NOT to fit either an electric start or extra spotlights (it did make me laugh! - its an old beezer for god sake!).
Also, Chris Goldby has been kind enough to email me, again in great depth, commenting especially on 'the 3rd wire' which caused me my original concerns. I have pasted it below as you just cant have enough info:
Hi Ray,
Ive been reading your posts on the forum and would like to get my twopennorth before you go and spend unnecessary amounts of cash at Kempton on Saturday.
Firstly, the alternator has nothing to do with being 6v or 12v. Its the power output that matters. All alternators had 3 wires up until about 1968, when Lucas used the zenor diode as the regulator.
The reason they were originally 3 wire was all the wires went to the switch, which acted as a 'regulator' when running day-time with no lights, it would allow power from one wire through to the rectifier. When you turned the pilot and rear lamp on, (running on sidelights) it would switch another one through, when you turned the headlight on all would be switched through.(each one is connected to 2 of the 6 coils in the alternator) This was to stop the battery boiling. When the Zenor, which is a regulator, came into use all three are connected and when the voltage gets to 14v, the Zenor kicks in and converts any extra to heat.
I have fitted many 3 wire into 2 wires in the wiring all you do is connect 2 of the three, colour immaterial, into one lead that goes to the rectifier, and the one left over, into the other rectifier lead. All the coils in the alternator then pump out all the power all the time, which is what you want. If you did what someone suggested and leave one of them out, you will only get 2/3 of the power which isnt enough.
Most spares suppliers do a Rectifier Regulator unit for about £30. Look on feked.com for their part ref fkreg123w. I have used a few of these and they do the job and last. If you use the £5 rectifier that you have bought, then they too are very reliable, although the terminals are a bit weak and when forcing the spade connector on they can snap off(dont ask how I know etc). However, you will then need to use a Zenor diode and heat sink to do the regulating.  A new Zenor can cost up to £30 and the Heatsink on top, makes the solid state one look far more economical.

I will study all the above, it all looks pretty straight forward - I do have a 'fully encapsulated' 6 coil Alt, complete with stator but I'm not sure of its condition, so I might just use what I've got and only buy new if needed - so I might wait for the next Kempton before spending hundreds of pounds.
Again many thanks for everyones input and I'm sure I now have enough info to take my project further - many thanks Ray T

STAR TWIN

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Re: A65 6v - 12v Alternator
« Reply #10 on: 18 May, 2017, 22:49:30 »
A good explanation but don't forget that here we are connecting a 2 wire alternator to a 3 wire harness. In this case, we can ignore the harness green/yellow wire which goes up to the light switch and connect the 2 remaining harness wires (green/black, white/green) to the alternator wires. It doesn't matter which alternator wires are connected to these 2 harness wires as each connects to a side of the rectifier (or preferably control box, as recommended).
An alternator on open circuit can give in excess of 26 volts hence the need for a control box or zener diode to control voltage output. The old 3 wire solution predates the availability of zener diodes or decent electronics and was adequate in much the same way a BSA 7" brake was considered adequate.     

EDDIE SIMPSON

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Re: A65 6v - 12v Alternator
« Reply #11 on: 18 May, 2017, 23:07:23 »
many moons ago i got stuck in traffic on the a1 on my trident t160 during a rainstorm. with electronic ignition and headlights and indicators it took about 3,000 rpm and plenty of popping and banging to get through that traffic. never again.  i decided to fit the mistral 3 phase. i converted to negative earth battery connection, used a suzy gs750 wiring loom , switch gear and a kawa gs500 regulator. i know i upset the purists but brought the bike up to modern standards for heavy traffic. the only problem is working out ways to mount a larger battery and regulator. i also prefer the jap bullets to lucas ones .
however if you keep the points system i don t think 3 phase would be necessary and points can be very reliable when well maintained. the boyer requires a lot more juice and i dont think the older alternator is adequate with lights and indicators and traffic.

TRIGWELL

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Re: A65 6v - 12v Alternator
« Reply #12 on: 18 May, 2017, 23:24:10 »
Again thanks for prompt response. So am I right in saying "single phase fully encapsulated alts. have 2 wires - my harness is expecting 3 - I guess it the wire to the lighting switch is the one we go without - is this correct? - ray t

STAR TWIN

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Re: A65 6v - 12v Alternator
« Reply #13 on: 19 May, 2017, 07:02:53 »
Yes Ray, that should e it. Best of luck!

JulianS

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Re: A65 6v - 12v Alternator
« Reply #14 on: 20 May, 2017, 12:52:58 »
Again thanks for prompt response. So am I right in saying "single phase fully encapsulated alts. have 2 wires - my harness is expecting 3 - I guess it the wire to the lighting switch is the one we go without - is this correct? - ray t

The encapsulated 6 pole single phase also came with 3 wires and was suitable for 6 volt and 12 volt applications. Below from 1971 Lucas manual.