Battery Switches.

[coopec43]

Originally Posted by daveNZ

In wiring the alternator +ve direct to the house bank, and where the is -ve is through the engine, where on the alternator would I wire the negative, just under the head of one of the mounting bolts?
And is there any reason to make +ve and -ve the same length?
Thanks.

Good question!

• Alternator positive terminal to the positive terminal on the house bank?
• Engine earthed to the negative terminal of the house bank?
• Alternator earthed (through the engine)

I'm sure I have read there should be a fuse/circuit breaker on the +ive lead? If so, my alternator is 24V 60A: What would an appropriate value fuse/circuit breaker be?

[kmacdonald]

Originally Posted by daveNZ

In wiring the alternator +ve direct to the house bank, and where the is -ve is through the engine, where on the alternator would I wire the negative, just under the head of one of the mounting bolts?
And is there any reason to make +ve and -ve the same length?
Thanks.

Make each as short as possible. No need to be the same length.

[kmacdonald]

Originally Posted by coopec43

Good question!

• Alternator positive terminal to the positive terminal on the house bank?
• Engine earthed to the negative terminal of the house bank?
• Alternator earthed (through the engine)

I'm sure I have read there should be a fuse/circuit breaker on the +ive lead? If so, my alternator is 24V 60A: What would an appropriate value fuse/circuit breaker be?

Depends. If the alternator output is wired directly to the house bank it should be fused within 7 inches of the battery. Fuse size is determined by the wire size. If it is wired to the starter solenoid battery terminal then it should be fused within 7 inches of the battery and fuse size determined by started current, about 300 amps would do. The fuse for the solenoid wiring example is optional but is a good idea.

[coopec43]

Originally Posted by kmacdonald

Depends. If the alternator output is wired directly to the house bank it should be fused within 7 inches of the battery. Fuse size is determined by the wire size. If it is wired to the starter solenoid battery terminal then it should be fused within 7 inches of the battery and fuse size determined by started current, about 300 amps would do. The fuse for the solenoid wiring example is optional but is a good idea.

My alternator is 24V 60A and is about 3 feet (one meter) from the positive battery terminal. Being such a short distance I'd probably use 8ga cable which (looking at my chart) can handle 80A. Does that mean a 60A +/- circuit breaker would be appropriate?

And if something does somehow trip the circuit breaker will that mean the alternator diodes will be destroyed?


Clive

[kmacdonald]

Originally Posted by coopec43

My alternator is 24V 60A and is about 3 feet (one meter) from the positive battery terminal. Being such a short distance I'd probably use 8ga cable which (looking at my chart) can handle 80A. Does that mean a 60A +/- circuit breaker would be appropriate?

And if something does somehow trip the circuit breaker will that mean the alternator diodes will be destroyed?


Clive

I'd use 4 ga and a 100A ANL fuse. 6 ga minimum. For a short run like that you could skip the fuse altogether if nothing could potentially short the wire. Depends how lucky you feel. Make sure you use the correct lugs. 1/4" alternator stud gets a 1/4" 4 ga or 6 ga lug depending on wire size. 5/16" or 3/8" lug for battery end. Genuinedealz.com can make then for you at reasonable cost if you don't have the tools to do the crimps.
If the fuse or breaker opens it could destroy the alternator diodes.

[coopec43]

Originally Posted by kmacdonald

I'd use 4 ga and a 100A ANL fuse. 6 ga minimum. For a short run like that you could skip the fuse altogether if nothing could potentially short the wire. Depends how lucky you feel. Make sure you use the correct lugs. 1/4" alternator stud gets a 1/4" 4 ga or 6 ga lug depending on wire size. 5/16" or 3/8" lug for battery end. Genuinedealz.com can make then for you at reasonable cost if you don't have the tools to do the crimps.
If the fuse or breaker opens it could destroy the alternator diodes.

I am far, far happier with what you suggest.

My intuition tells me to use heavy cables where batteries, alternator, winches, inverters, or distribution board are concerned. (I have used a minimum of 3ga but mostly 2ga on my 24V system)

As far as lugs are concerned I have appropriate sizes for the cable as well as the stud. I also bought a crimping tool though I wish now I had bought a hydraulic one.

Thanks for your help: I feel a lot happier now.


(I have just bought a 100A ANL Fuse. I have had nightmares thinking about whether my yacht will float with all the "extras" I am installing)


Clive

[Sailmonkey]

Originally Posted by coopec43

Good question!

• Alternator positive terminal to the positive terminal on the house bank?
• Engine earthed to the negative terminal of the house bank?
• Alternator earthed (through the engine)

I'm sure I have read there should be a fuse/circuit breaker on the +ive lead? If so, my alternator is 24V 60A: What would an appropriate value fuse/circuit breaker be?

On a steel boat don’t you want your alternator and starter to be isolated ground?

[coopec43]

Originally Posted by Sailmonkey

On a steel boat don’t you want your alternator and starter to be isolated ground?

My yacht is f/g so I'll leave that problem to others.


Alternator and Starter Isolation - Cruisers & Sailing Forums

www.cruisersforum.com › ... › Electrical: Batteries, Generators & Solar
Jul 18, 2005 - 15 posts - ‎5 authors
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[Sailmonkey]

Originally Posted by coopec43

My yacht is f/g so I'll leave that problem to others.

My bad, my brain for some reason associates Roberts builds with steel.

[coopec43]

Originally Posted by Sailmonkey

My bad, my brain for some reason associates Roberts builds with steel.

Don't feel too bad.

He used to push fiberglass with his designs but when fiberglass became prohibitively expensive he now pushes steel, aluminum.

Clive

[coopec43]

People with a non technical background may be interested in this article on alternators and how to install them

wilbo666 / Toyota Alternators

[coopec43]

I am trying to find a plug to fit the male plug on the alternator.

I think I understand the terminals

• Ignition (Ig)
• Sensor (S)
• light( L)

But what do the terminals labelled "E", "F" and""N" equate to and what do they mean?


Clive