Need help on alternator wiring

Farmall H, HV & Super H, 300 & 350, 1939-1958

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Rick Spivey
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Need help on alternator wiring

Postby Rick Spivey » Fri Mar 31, 2017 7:58 pm

Sorry to post a question that has probably been answered before, but I am not an expert on the electrical side. My "H" (I know, I'm in the Cub forum, but I'll get more hits that way, and it doesn't matter) was "converted" to 12 volt in a previous life. It has never kept the battery charged since I got it, but being magneto ignition, not big deal. However, I am tired of hand cranking it. So today I took the alternator in and had it tested, Delco 3 wire. It tested good, so I knew the issue was wiring. Mine looks a lot like diagram 5 in the wiring diagrams (M alternator), but no battery ignition. Therefore, wire 1 was not present. Wire 2 was connected toy the post as shown. I see that wire 1 has the diode included, and I don't trust my memory on what that is for.

Will my system work correctly if that wire is not there? And if needed, what do I connect it to, since I have a "kill" switch, and not an "ignition" switch?
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Eugene
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Re: Need help on alternator wiring

Postby Eugene » Fri Mar 31, 2017 8:48 pm

OK. You need the #1 wire connected in some manner. The number #1 wire excites, starts the alternator charging.

Since you have no battery powered ignition (switch). Couple of alternatives.
1. Purchase a single wire Delco clone. Simple installation.
2. Add a toggle switch to excite the alternator. Both my WD Allis' have the toggle switch. Hot wired to amp gauge. Flip the switch on shortly after engine start up, starts the alternator charging. Then immediately switch to off. Alternator remains charging until engine shut off.

Edit: If you forget to switch the #1 wire off, next morning, dead battery.
I have an excuse. CRS.

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Re: Need help on alternator wiring

Postby Gary Dotson » Sat Apr 01, 2017 7:20 am

As Eugene suggested on the switch, except you can use a momentary push button (starter type) switch and there will be no chance of leaving it turned on. The only down side to the switch is that you have to remember to push it after starting the tractor each time.

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Re: Need help on alternator wiring

Postby Eugene » Sat Apr 01, 2017 9:44 am

If you use a manual switch, you don't need the diode or lamp. The diode or lamp in #1 wire is to prevent the alternator from back feeding the battery powered ignition.

I put the switch in an existing hole in the dash on my Allis' and an IH B that I use to own.
I have an excuse. CRS.

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Re: Need help on alternator wiring

Postby Steve-N-Tn » Sat Apr 01, 2017 5:56 pm

Rick, have heard some use a push button instead of a switch which eliminates the chance of leaving the switch on. Will find out as I think I'm going to do my H the same way! Regulators cost more than an alternator these days!!! Hope it works! Steve


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