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Old 06-07-2009, 08:29   #1
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How to Wire an Alternator

Hey All,

I have your basic alternator at this time, it is a 65 Amp Delco Alternator. On the back it has 2 wire terminals, One says battery and the other is blank. Where should I run the one that says battery? To my engine batteries, house batteries or to the back of my battery selector switch (which just says 1 or Combination on it). And then where does the second wire go too? These two terminals are the ones with the big bolt to hold the wires in place. I have two other wire connectors also, they are the small male terminal type. I assume that these two wires will go to the Amp meter. I would like to use the Amp meter on my electrical panel and not the one outside at my engine control panel.Could someone please tell me the best way to wire up an alternator so both my house and starter battery get charged properly. Thank you so very much.

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Old 06-07-2009, 08:38   #2
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Sea Maid,
it all depends on how your batteries are wired up. In general the large terminal that says BAT should be a battery cable running directly to your motor bank. THe two small male terminals should be marked. where they go depends on if tis an external or internally regulated alternator. Assuming its externally regulated those two small terminals ( which are marked " f" and "r" go to the regulator and the starter switch "f" is the excitation wire that goes to the starter switch and "r" goes to the regualtor. Get a copy of Calders Book electrical and mechanical maintenance for boat owners, it will help a lot.
If the alternator is internally regulated the two male terminals go to the starter switch and amp meter ( I think I have this right)
hope this helps

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Old 06-07-2009, 09:34   #3
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There are as many different alternator configurations as there are brands of coffee. If you start moving wires around without knowing where they need to go it could get expensive fast. You either need help, or first read a book like Calder and seond figure out WHICH 65 amp Delco alternator you have and how it is regulated.

PS-- The best part of Rhosyn Mor's advice is to read the book--I don't think the guesses as to which terminal goes where are correct.
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Old 06-07-2009, 09:51   #4
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Check out the Delco-Remy Instruction Sheets & Service Manuals:
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Old 06-07-2009, 10:40   #5
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Thank you, Thank you, Thank you. I have the basic 12v electrical book, now I know which book I really need to have and Gord thanks for the link to the Instruction and Service Manual. I love this site. Thank you again for taking the time to write back.
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Old 06-07-2009, 13:17   #6
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On that size of Delco Remy alternator (100 amp and less) the two male spade connectors that peak up through a square shaped hole have nothing to do with an ampmeter. One of them is labelled #1 and should be on the left when looking at it from the rear. You need a jumper wire connecting this terminal #1 to the battery terminal (+ive, usually mounted on a red plastic insulator) on the back of the alternator.
The one labelled #2 is used in combination with #1 for an optional external regulator.

If you want to hook up a tachometer you will have to open up the case and attach a wire to one of the terminal screws on the diodes and lead it out of the case. It is easy to do. When you open the case make sure that the field coil inside stays with the rear side of the case and not the side with the pulley. You may damage some leads to the field coil if you pry it the wrong way.
You will need to temporarily secure the brushes with a short length of wire when you reassemble. The brush holder has a set of holes that line up with a hole in the aluminium case. Insert the securing wire through here. Simple.
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Old 06-07-2009, 13:20   #7

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Seamiad, Delco and Delco-Remy (two different companies) both have toll-free numbers and will gladly help you to identify your alternator, and then wire it up correctly. They have most of the technical materials available online as well--but they're really, really, helpful folks.

If that is a standard alternator, it is only meant to charge one battery/bank. Making it work properly for two involves some choices and compromises, you can see those detailed on Blue Seas' and other marine electric equipment web sites. Battery swtiches, power combiners...a number of options to suit your budget.
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Old 07-07-2009, 13:49   #8
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