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Old 14-01-2016, 15:28   #1
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Wire size on alternator

Does anyone know the size wire that comes off of the alternator and goes to the batteries. I need to replace the connector on the wire and did not get the size when I left the boat today.
12 volt 60amp

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Old 14-01-2016, 16:09   #2
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Wire size on alternator

This is not a universal thing - I have no idea how you would get a reasonably accurate answer to this undefined question. If you only need a connector, I would suggest you buy one in every size from 4 to 2/0. They are cheap, and that range should cover it.

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Old 14-01-2016, 17:04   #3
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Re: Wire size on alternator

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Originally Posted by landonshaw View Post
Does anyone know the size wire that comes off of the alternator and goes to the batteries. I need to replace the connector on the wire and did not get the size when I left the boat today.
12 volt 60amp

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Most likely #10 wire. Don't forget the shrink tube.


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Old 14-01-2016, 17:07   #4
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Re: Wire size on alternator

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Originally Posted by colemj View Post
This is not a universal thing - I have no idea how you would get a reasonably accurate answer to this undefined question. If you only need a connector, I would suggest you buy one in every size from 4 to 2/0. They are cheap, and that range should cover it.

Mark

Really more depends on the Alt Amps and length of the run to the battery.
Most systems at 60 Amps wouldn't need any larger than #8 wire.


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Old 14-01-2016, 17:24   #5
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Wire size on alternator

Quote:
Originally Posted by Boatyarddog View Post
Really more depends on the Alt Amps and length of the run to the battery.
Most systems at 60 Amps wouldn't need any larger than #8 wire.


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For a 3% voltage drop, a 6' run to the batteries would require #4, while a 30' run would require 2/0. The smallest that should be used for a very short run (3' or so) is #6.

#8 or #10 should not be used at all unless one is satisfied with low performance from their alternator.

However, all of this is meaningless because the OP is asking us what size wire he has.

There is no way for us to know this.

Mark
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Old 14-01-2016, 18:18   #6
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Re: Wire size on alternator

Not only can I not hazard a guess at the wire size, the hole size in the ring throws another wrench into the works.


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Old 14-01-2016, 19:13   #7
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Re: Wire size on alternator

Quote:
Originally Posted by colemj View Post
For a 3% voltage drop, a 6' run to the batteries would require #4, while a 30' run would require 2/0. The smallest that should be used for a very short run (3' or so) is #6.

#8 or #10 should not be used at all unless one is satisfied with low performance from their alternator.

However, all of this is meaningless because the OP is asking us what size wire he has.

There is no way for us to know this.

Mark

I'm not sure where you got that calculation, but at 60 amps load on a 12 vt circuit, with #8 copper conduit in a 6 ft run, you'd see about 3+\- % loss, or 13.5vts, would be close to 13.05 vets at the load. Or just 1/2 volt.
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Old 14-01-2016, 19:16   #8
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Re: Wire size on alternator

Quote:
Originally Posted by Boatyarddog View Post
I'm not sure where you got that calculation, but at 60 amps load on a 12 vt circuit, with #8 copper conduit in a 6 ft run, you'd see about 3+\- % loss, or 13.5vts, would be close to 13.05 vets at the load. Or just 1/2 volt.
Attachment 116761
http://www.calculator.net/voltage-dr...es=60&x=66&y=9


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Round trip.


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Old 14-01-2016, 19:25   #9
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Re: Wire size on alternator

Good practice these days is take pics of everything with your smartphone camera... you can do a lot with those pics... and this question would probably answerable. When you are in the chandlery you can look for the pic and then find the product!
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Old 14-01-2016, 21:50   #10
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Re: Wire size on alternator

If you do not know what the wiring is sized at and it will be inconvenient to make a second trip I'll second the suggestion of purchasing an assortment of terminals. I would suspect you probably have 10 gauge wire coming off your alternator if you are working on a 33 ft boat but you can just get a foot of 10 ga wire, so if I am wrong just crimp the wire to the proper terminal and splice it to the end of your existing wire.
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Old 15-01-2016, 03:33   #11
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Re: Wire size on alternator

I intend to buy a number of sizes to make sure that I don't get out to the boat and not have the proper size. The run is less than 5 ft. I agree that a pic would be great, although I did not think of this until I was ashore and if I had taken a picture, I would have thought at the time to look at the wire and not had to ask the question. Thanks for your help.


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Old 15-01-2016, 03:41   #12
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Re: Wire size on alternator

I usually have a bunch of spare connectors lugs and crimp connectors OB... another good practice... even when I dip into spares I then replenish them. Having to make a and hr trip for a $1 part is crazy.
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Old 15-01-2016, 04:45   #13
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Re: Wire size on alternator

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Originally Posted by Sailmonkey View Post
Round trip.


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???
The negative side is usually the alternator case and the engine and then the BIG negative cable from engine to battery.
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Old 15-01-2016, 05:36   #14
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Re: Wire size on alternator

Silly question, usually the wire from the Alt does run to the battery bank,
But, three ft or less away from the Alt. is usually the starter solenoid, that has a HUGE wire that also goes to the bank. So why not just take your Alt wire to the solenoid?

I believe my stock Yanmar wiring harness had a 10Ga wire, though it may be an 8
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Old 15-01-2016, 05:41   #15
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Re: Wire size on alternator

I never depend on case ground, imo, increases depletion of the engine zincs by increasing current flow thru the block. If there is not a dedicated ground attachment point ON the alternator, I always run a seperate ground, same size as the output wire, from the mounting bolt.
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