Alternator issue

[capecodder116]

The boat is a 1984 22' Tiara Continential, 260 mercrusier engine with Thunderbolt 4 ignition.

At the end of the season my voltmeter on the dash was acting speratically charge....not charging....diagnoised the problem to be my alternator.

I took the alternator to a shop that does rebuilding. Long and the short of the story is I thought he was going to rebuild my prestolite alternator but when I went to pick it up the other day he gives me a new alternator which only needs one wire (red to battery) and the ground. He tells me, "not to worry just tape off the remaining wires as they will not be used."

The "remaing wires" are two small red wires going to one terminal and a single purple wire going to another terminal on the alternator. I do not know where the wires ( two small red and single purple) terminate on the other end, and I am a bit skeptical about this....I am concerned if I do what he has suggested I may cause damage else where to my electrical system.

My question is, is what he is telling me correct..??? And where do the two small red and single purple wire terminate as I do not have a wiring schematic.

 

[Bondo]

Re: Alternator issue

My question is, is what he is telling me correct..???

Ayuh,....

The 2 red wires are probably to the voltage regulator,+ the purple should be the igntion circuit...

Tape them up individually, not together...then to the harness...

 

[capecodder116]

Re: Alternator issue

Thanks Bondo....can you explain what is different with this new style alternator vs. the original Prestolite..??

 

[Bondo]

Re: Alternator issue

Ayuh,... The Regulator is Built-In....

 

[dan t.]

Re: Alternator issue

the only issue with 1 wire alternators is that they dont always kick in on start up . some times you have to rev them up fore a few seconds to make them start to charge

 

[J JACKSON]

Re: Alternator issue

is the new one wire a marine alternator?

 

[capecodder116]

Re: Alternator issue

Yes, the new alternator has one red wire...I don't understand if one or two of the other wires (small red) return to an external voltage regulator as Bondo mentioned, where is the external regulator located as I can not find it. As I mentioned in my opening post, I don't have a wiring schematic so I can't trace the two small red wires back.

 

[Bondo]

Re: Alternator issue

I don't have a wiring schematic so I can't trace the two small red wires back.

Ayuh,..

There's a Wiring Schematic, Right here in the factory Manual,...
It's a Monster of a file, so right-click it,+ save it to file, then go to bed...
It should be in your documents by morning,.. Depending on your internet speeds...

 

[rodbolt]

Re: Alternator issue

your fine.
the original altenator was an internally regulated non-self exiting unit.
the new unit is internally regulated self exiting.
to make alternating current you have to spin a wire,or coil of wires,through a magnetic field.
in the case of a belt driven altenator you pass a small electric currnt through the stator winding(now a magnetic field) and then spin the rotor(another coil of wire) through the stator field and pick the voltage off the slip rings on the rotor.
older stuff had to be excited(stator field created) with an external voltage called an excitation current. the single wire setup has a residual magnetic field and internal solid state circuitry to allow enough magnetism to remain for self excitation. thats also why as they age you usually have to rev the engine some to get an output.
the AC voltage and frequency is controlled by the size of the windings,the size of the residual magnetic field and the speed of the rotor.
increase any of the 3 and the output from the slip rings increase.
as we can change the winding size or the residual field easily the one thing that is easy to control is rotor speed as its attached to crankshaft speed via a drive belt.
on your old setup the purple wire was an excitation wire,supplied stator current at key on, the red wire was a battery sense wire that sensed battery voltage for the internal regulator and the big orange or red wire was regulator output to the battery.
the newer stuff simply uses less wire and is internally excited and controled making everything more simple.

 

[Bondo]

Re: Alternator issue

Ayuh,... Thank you Rodbolt,...

I just leaned something,... I guess that makes today a Great day....

 

[chiefalen]

Re: Alternator issue

Would you also agree the simplest would have been to replace a 3 wire with a 3 wire.

Thats what i did, went to e-bay and bought the right wire wise alternator.

And the bonus was more amps, i believe the one i had was 55 amps the one i received was 100 amps.

And the best part, it was 1/3 what they wanted around here.

I bought starters also from the same guy DB electrical.

He also had a starter for my sons Mountaineer, 1/3 the price.

 

[rodbolt]

Re: Alternator issue

cant believe no one busted my chops .
I reversed the stator/rotor field current.
in modern altenators as opposed to generators the magnetic field current is provided via the slip rings to the rotor.
the AC output is taken from the stator windings,normaly Y wound ,and fed to the rectifier diodes.
I simply reversed it in the previous post.
to much time helping a buddy with a 49 ford tractor generator .
but the outcome is the same.
spin a wire through a magnetic field(generator) or spin a magnetic field through a stationary coil of wire(altenator) and the results are mostly the same.
an electric current is produced.
from there the controling feature is the strenth of the magnetic field,the speed of the field and number of turns on the stator(a/c) or the field coils(generator).