Replacing 3 wire Alternator with 1 wire

[tlynch99]

Hello,

I have a 97 350 with an Alpha drive, that has a bad alternator. I purchased a 105Amp single wire Delco alternator and have a couple questions about replacing it.

From the wiring diagram and some things I have read online, the Orange wire (See pic) is the positive wire, and goes over to the starter. It connects at the starter to the positive side of the battery system and does it's thing.

If I replace the current 3 wire with a 1 wire, can I just connect the old Orange wire to the single post on the alternator? Or should I run a new wire from the alternator to the engine side (not battery side) of my battery switch?

My second question is, if I just connect the orange wire, is it large enough to handle the increased alternator size? I think the old alt was 55 or 65 amp, where this one is 105A.

At a minimum I will cap off the other two wires.

Engine:
ENG:* 0K282550* 4350100KS* 1997* MERCRUISER* TB5, W/PS, TWOPCEX, WORO* 350* ALPHA*

 

[spdracr39]

Re: Replacing 3 wire Alternator with 1 wire

You should be able to use the same wire and just attach it at the battery post ( on the alternator ) like the old one. Capping and taping the other two is a good call. Most of the one wires I have used you have to give it a little rpm before it will start charging so don't just start it and let it idle hoping it will charge rev it for a second and check your voltmeter.

 

[rodbolt]

Re: Replacing 3 wire Alternator with 1 wire

depends on how yours is wired, some ran the alt take off to the fuse on the starter,some ran it directly to the battery lug on the starter solinoid.
however I dont think the existing 10Ga wire can handle 105 amps,thats close to double the amperage of the stock unit.
most 105 amp alternators are wired with 8 or 6 Ga wire.
if yours runs to a fuse mounted on the starter lug then be aware that fuse is typically 65 to 90 amp rated and can blow with a 105 amp alternator to it.
if you have any battery isolators they must be rated for 105 amps as well.

 

[Bondo]

Re: Replacing 3 wire Alternator with 1 wire

I purchased a 105Amp single wire Delco alternator

Ayuh,... Is it Marine rated,..??

Why the Huge Amperage,..??

 

[tlynch99]

Re: Replacing 3 wire Alternator with 1 wire

Yes it is a marine rated alt. I choose that one because it was mentioned as a good replacement.

I will look into seeing if it goes back to a fuse. The wiring diagram shows the positive wire just running back to the positive post on the starter.

 

[rodbolt]

Re: Replacing 3 wire Alternator with 1 wire

105 amp is pretty standard on large motors today.
means when I am repowering I usually have to go to a larger Isolator and isolator wiring.
I dont have it handy but the information is readily avalible on wire size,wire run lenth and maximum amperage it can stand.

 

[tlynch99]

Re: Replacing 3 wire Alternator with 1 wire

That makes sense, the company I bought the alternator from, recommended it, when replacing the alternator on my motor.

I don't belive I have an isolator on this motor. Should I install one?

 

[rodbolt]

Re: Replacing 3 wire Alternator with 1 wire

battery isolators are typically used when charging 2 or more batteries from 1 or more engines while keeping all but the starting battery isolated from the engine.
dunno how many batteries you have nor how they are wired.

 

[tlynch99]

Re: Replacing 3 wire Alternator with 1 wire

Ok I don't think I need isolators then. I have two batteries and they are both wired to a battery selector switch.

 

[zbnutcase]

Re: Replacing 3 wire Alternator with 1 wire

According to the info I dredged up while upgrading the charging system on my truck, 60-90 amps, at a run of 5 feet or less (from alt to batt) requires a MINIMUM of 6GA cable. I used 4GA for my 105A CS-130 alts (I have two on it)