Combine 3 wires from the alternator to the rectifier?

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gale1959

gale1959

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I have a 1970 Commando S with a Tri-spark charging system. I am rewiring the bike and will hide some of the wires. In doing so I thought to combine the 3 yellow wires from the alternator into one and run it through the frame. Once it exits the frame I would connect it to the 3 wires from the rectifier. I don't see an issue doing this. Am I wrong?

Combining the three wires into one will require a wire that can handle 14.5 amps or 14 gauge wire (carries 15 amps). I plan to use a 12 gauge wire (it can carry 20 amps so I have some safety margin).

Your thoughts are appreciated.
 
gale1959 said:
I am rewiring the bike and will hide some of the wires. In doing so I thought to combine the 3 yellow wires from the alternator into one and run it through the frame.

Combining the three wires into one will require a wire that can handle 14.5 amps or 14 gauge wire (carries 15 amps). I plan to use a 12 gauge wire (it can carry 20 amps so I have some safety margin).

Your thoughts are appreciated.
Click to expand...

Don't. As it won't work.
 
As LAB says, it won't work. Each alternator wire must connect to a separate regulator terminal for the system to function.
 
Thanks guys. With no specific terminal identified to connect the three wires too I thought it wouldn't matter that I combined them and I could just then hook them up to the 3 wires at the rectifier. Clearly there must be some consideration for carrying capacity of each wire.
 
No - it is the phasing of the stator windings (and the multiple output wires) that allows the higher output of the 3-phase alternator/regulator. If you join the wires together at any point you will cancel the alternator's output. It doesn't matter which wire connects to which regulator terminal but they MUST each connect to an individual terminal.
 
The wires may be all the same colour, but they are connected to different coils inside the alternator stator.
Combine 3 wires from the alternator to the rectifier?
It doesn’t matter which order they are connected to your regulator/rectifier but they must not be connected together.
 
L.A.B. said:
Don't. As it won't work.
Click to expand...

I agree with LAB.
From your statement you clearly don’t understand electrics, alternators are altering current 3 phase electrics as opposed to Direct Current (12 v DC) from say, a dynamo - the AC comes on in stages according to the draw of current/light switch position. Attempting to use your method will feck it up and wreck the alternator completely if not cause a fire.
 
Bernhard said:
alternators are altering[alternating?] current 3 phase electrics as opposed to Direct Current (12 v DC) from say, a dynamo - the AC comes on in stages according to the draw of current/light switch position.
Click to expand...

You appear to be thinking of a 3-wire Lucas alternator which is single phase with a third output wire brought into play when the lights are switched on. This type of alternator was used on many 1960s British motorcycles and is not "3-phase".

http://www.caferace.com/6Vto12V.pdf

"Lucas Wiring DifferencesDifferences in Regulation. You also need to understand some background wiring information. Lucas 12V systems use"electronic" regulation; 6V Lucas systems used "mechanical" regulation. Whereas the later 12Vsystems used a Zener to keep from over-charging the battery, back during the 6V days there were no such electronic wonders. 6V regulation was achieved using a “3-wire stator”; a single stator with 2 outputs (1 Low, 1 High). Today people largely forget that there was simply no other way to achieve voltage regulation in a box small enough for motorcycle applications. During daylight hours with a 6V system (headlamp OFF) your bike ran on the Low alternator output. When you switched ON the HL at night, that same switch also turned on the High alternator output. The loads on the electrical system were simply matched to the alternator output and that kept the battery from over charging. You can easily spot these systems; they're the ones with rotary HL switches."



http://www.aoservices.co.uk/info/ALTERNATOR_COLOURS.pdf

"3 Phase.
This phrase trips up a lot of people, just because they see three wires they think they have 3 Phase, which they have heard about-very often it is NOT SO..............

.........To have a 3 phase stator you must have 9 pole pieces(not 6). These are known on paper (ie never marked on the unit) as RM24 but there are different outputs which are shown by the numbers (if you can find one on the unit)."

https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/rectifier-circuits/

Combine 3 wires from the alternator to the rectifier?
 
Last edited:
Bernhard said:
I agree with LAB.
From your statement you clearly don’t understand electrics, alternators are altering current 3 phase electrics as opposed to Direct Current (12 v DC) from say, a dynamo - the AC comes on in stages according to the draw of current/light switch position. Attempting to use your method will feck it up and wreck the alternator completely if not cause a fire.
Click to expand...

That being said I'm glad that @gale1959 asked the question. It's better to ask and be corrected than to find out the smokey way. You don't learn unless you ask!
 
And you Mr. Bernard are clearly omniscient and rude. I’m sure your encouraging approach will drive others to ask additional questions so you may then pontificate to the extreme.

Thank you,
Scott


Bernhard said:
I agree with LAB.
From your statement you clearly don’t understand electrics, alternators are altering current 3 phase electrics as opposed to Direct Current (12 v DC) from say, a dynamo - the AC comes on in stages according to the draw of current/light switch position. Attempting to use your method will feck it up and wreck the alternator completely if not cause a fire.
Click to expand...
 
Last edited:
gale1959 said:
And you Mr. Bernard are clearly omniscient and rude. I’m sure your encouraging approach will drive others to ask additional questions so you may then pontificate to the extreme.

Thank you,bScott
Click to expand...


Well, sorry you took it that way, but if you would be happier ruining your alternator and setting your bike on fire. . . . . . . .
 
Bernhard said:
Well, sorry you took it that way, but if you would be happier ruining your alternator and setting your bike on fire. . . . . . . .
Click to expand...

But he didn’t ruin his alternator and he didn’t torch his bike as your future reading crystal ball predicted.

He asked first.

If a guy requests help/guidance how does dumping on the guy amount to anything helpful?
 
mikeinidaho said:
Not to mention weakening the frame by drilling holes in it.
Click to expand...

+1. There is not a real good way to do this without weakening the frame, potentially ruining the resale value of the bike and making it easier to chafe the insulation off the wires. To pass multiple wires thru the tube and allow for some kind of grommet for protection of the wiring it takes too large a hole. I would walk away from any bike modified such unless I was buying it for parts only. Additionally it is good to be able to get to your wires.
 
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