Wiring up a 12V Alternator

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yves-jeep
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Wiring up a 12V Alternator

Post by yves-jeep » Tue Aug 24, 2021 9:10 am

Hi all,

I'm hoping someone here can help me.

My 1943 Ford GPW came with an alternator when we bought her, with an external regulator. Not knowing much about Jeeps, I rewired using a new MV spares wiring harness not realising it was an alternator and not a generator, so I didn't make careful note of the wiring that I took out (my stupid mistake). However, now I know it's an alternator, I am looking at trying to refit the regulator that went with it originally (I had bought a JMP regulator, but have now been told that won't work with an alternator). I threw no parts away, so I have all the wiring I removed stored away. I need to know where to run the battery line to the alternator from, and where to run the line to the regulator from. I've looked at generic wiring diagrams, but they've proven no help. Essentially, I need to know if I can use the existing wire between the ammeter and the regulator for the alternator's regulator or run a new line according to this diagram (which most closely resembles the arrangement I've got).

Wiring diagrams / photos / explanations all greatly appreciated. Thanks !
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"Evie"
Ford GPW 167116, Dec 43
Engine No. MB408680
Served in Australia and restored to Ford Factory Markings


Gunny
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Re: Wiring up a 12V Alternator

Post by Gunny » Tue Aug 24, 2021 9:40 am

I too am very interested in this subject, photos, diagrams, would be ideal!
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Wolfman
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Re: Wiring up a 12V Alternator

Post by Wolfman » Wed Aug 25, 2021 5:17 am

This seems like a simple enough question, but, yves jeep, don't know the make or model alternator you have. Since you are in France, something that would be found in Europe ?
And Gunny, same for you, only U.S. or far east made ??.
The diagram posted is generic for an external regulated alternator. Battery wire to the alternator and an external regulator connected to a field terminal to control the field and Alt. output. The regulator would have a switched power wire in.
Multiple wire, internal regulated alternators have the same big battery wire to the alt. battery terminal. A switched wire that turns on & off with the ignition and a system voltage wire that tells the regulator what the system voltage is so it can adjust accordingly. Possibly an idiot light wire and external ground connections.
One wire is the easiest. One big battery wire to the battery connection.
Mounting an alternator in place of a generator. Alternators come in all different sizes. You just have to get creative.
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Jim Thomason
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Re: Wiring up a 12V Alternator

Post by Jim Thomason » Wed Aug 25, 2021 3:31 pm

Yves
MB/GPW alternator wiring
Using your new (reproduction) wiring harness. The wire that would normally go to the "B" connector on a stock regulator system ( I believe it is red with white marks ) is to be connected direct to the large output post on the alternator; it does not go to/through any regulator. This red wire goes thru the firewall and a fileret (if you have one--- there are recent post on that subject) ,then to the Amp gage. From there the jeep wiring system is unaffected by the installation of the alternator.----other than voltage being 12 volts --this affects the gas gage annd lights.

Using an alternator that has to have a regulator : I believe you stated you have the regulator and its wires you removed at the begining of work. Re install it as it came off with the regulating wire going to the Alternator. This regulator must be mounted so that it is grounded. The wire that supplies power (12 volt) to the regulator should be run through the firewall and connected to the Ign switch. If it is connected to the coil post, when the switch is turned "off" the engine could continue to run due to "feed bacK" from the alternator (Not all altertnators do this). If you have this problem, you will have to use a ignition switch with an accessory power post along with a coil power post. Connect the alternator regulator power wire to the accessory post---NOT the coil post. This two post switch can be avioded by putting a diode into the switched hot wire to the voltage regulator. That is a subject for another posting.
Remember to install the battery with negetave ground. Jim

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Re: Wiring up a 12V Alternator

Post by dpcd67 » Mon Aug 30, 2021 6:06 am

Without reading all the above, get a one wire GM Alternator. They are cheap. Then you you have, one wire to hook up. That is the easiest solution, if you want easy. They have built in regulators, so you do not wire up your original. Paint it black.
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Re: Wiring up a 12V Alternator

Post by FredRG » Tue Jan 04, 2022 4:38 pm

dpcd67 wrote:
Mon Aug 30, 2021 6:06 am
Without reading all the above, get a one wire GM Alternator. They are cheap. Then you you have, one wire to hook up. That is the easiest solution, if you want easy. They have built in regulators, so you do not wire up your original. Paint it black.
This seems a good solution. My neighbor mentioned he will be working on a Ford GPW soon after he finish installing the suspension from 4Wheelonline onto his Wrangler and sold it. The previous owner messed with the alternator wiring so he needs to address it first.

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Re: Wiring up a 12V Alternator

Post by Rod Rushton » Tue Feb 01, 2022 8:03 am

Over the past 8 years,I have supplied more than 200 x 12v Alternator kits and about 75 x 24v ones to Jeep owners world wide.
I use Lucas type 217 which conveniently are both the same size, one is for 12v, the other 24v
The universal mounting bracket can accommodate both and is adjustable for the different drive belts
The only trouble I have ever had is when an owner spray painted one black without masking up the cooling vents
RR
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FORD GPW 202055 DoD 5 - 22 - 44 Serial# 20534360
MBT # 25553 DoD 4 - 43
Piper Cub 1944 L4H 480015 G-AKIB

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