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I'm rewiring my 35, it has a chrome GM 140amp 1 and 3 wire alternator (from amazon) that the previous owner fitted, BUT all 3 wires connect onto one post on the alternator, therefore it is only a 1wire (which is less efficient than a 3 wire), so I want to replace it with a real chrome 3 wire one. what do you think?
 

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Have you tried wiring your present alternator this way. When you say less efficient what do you mean. A single wired alternator need to run at a certain speed before it gets excited and starts charging, once it has started charging it will carry on charging even when the speed drops. A 3 wired alternator will start charging as soon as it is turning due to being excited by power from the green wire.
524622
 

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Thanks lads for your responses, the existing alternator doesn't have pin 1 and 2 just the threaded stud, yes I want a charging light. I'm not bothered about simplicity as I'm an electrician (not vehicles though) and am totally rewiring the car due to a thousand bodge ups n loose live wires!! Where is the best online shop to get the right one
 

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If you must swap back to a 3-wire setup , you'll have to change the internal regulator to a stock , non- self- exciting version. There are many places to buy a regular alternator . If you have a dash mounted volt meter , there's no need for a light .....
 

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Just watch on Youtube on how to change the regulator from 1 wire to 3 wire as "2old2fast" mention. Under the boot I mentioned It looks like the single wire has the 2 small terminals covered in plastic and the 3 wire they are bare. If it is a single wire regulator and you can get the 3 wire regulator it is not a hard job to change it over.
 

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With any charging issues, first check grounds. Engine must be grounded to frame. Body must be grounded to frame. Battery must be grounded to engine or at least to frame if battery is in trunk. Think about it. Engine is not automatically grounded. Engine mounts, trans mount, rear shackles or links, exhaust pipes, are all rubber or polyurethane mounted. I've seen cars with only grounds being the throttle cable and / or E brake cables. Poor grounds at best. I've seen many electrical issues attributed to bad or nonexistent grounds. Click below. Use braided grounds.

Ground Strap Braided, 13 In copper tin plated C8860525 (M) | eBay
 

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Personally I like having my idiot light working along with a volt meter. Makes it almost foolproof for this fool.
And with a 3 wire alternator, you can run the sense wire to the fusebox if you like and it will raise the output so that you get full voltage there even if there is a voltage drop from the alternator to the box. So the more excessories (like headlights;) ) will be automatically compensated for and you will still get full voltage to the fusebox.
 

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Personally I like having my idiot light working along with a volt meter. Makes it almost foolproof for this fool.
And with a 3 wire alternator, you can run the sense wire to the fusebox if you like and it will raise the output so that you get full voltage there even if there is a voltage drop from the alternator to the box. So the more excessories (like headlights;) ) will be automatically compensated for and you will still get full voltage to the fusebox.
That's a new theory ...
 

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Discussion Starter #13
A 3 wire alternator is more effective than a 1 wire (according to Mad electrical). The car has loads of electrical issues including poor earthing.................that's why it's totally ripped out. But if I'm gonna do a job, I'm gonna do it exactly right that way you don't have to revisit the work again 5 years later.

Brad.....................you were spot on!!..............I found a rubber bung n removed it n there were the two pins, where can I get a proper plug to fit?
 

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I'm rewiring my 35, it has a chrome GM 140amp 1 and 3 wire alternator (from amazon) that the previous owner fitted, BUT all 3 wires connect onto one post on the alternator, therefore it is only a 1wire (which is less efficient than a 3 wire), so I want to replace it with a real chrome 3 wire one. what do you think?
If it were mine I would go with the three wire setup just because that’s how the factory did it but the single wire would be ok too. The important thing is to have the proper gauge wire from the alternator to the battery positive. If the battery is under the hood , a 6 gauge wire, if in the trunk , 4 to 2 gauge wire. Sounds like overkill but it will guarantee that 140 amp alternator will deliver the power it’s capable of.
 

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Discussion Starter #18
The battery is in the boot (900cca), I'm running 00 gauge wires (live and earth) up to the starter n then to junction boxes on the firewall. People don't realise that the earth wires must be the same gauge as the power wire cos the current also flows down the earth (I think you call it 'ground').
As an electrician, I know that the wire gauge is critical n that a wise man will always use one size bigger..............especially on a car because unlike a house/ factory, 12 volts is so weak, it only has the electrical 'force' (volts) of a bit of limp lettuce!!
 

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The battery is in the boot (900cca), I'm running 00 gauge wires (live and earth) up to the starter n then to junction boxes on the firewall. People don't realise that the earth wires must be the same gauge as the power wire cos the current also flows down the earth (I think you call it 'ground').
As an electrician, I know that the wire gauge is critical n that a wise man will always use one size bigger..............especially on a car because unlike a house/ factory, 12 volts is so weak, it only has the electrical 'force' (volts) of a bit of limp lettuce!!
Your last statement spells out the reason why a 3 wire setup is more efficient than a 1 wire. The built in regulator has to “see” system voltage and when it’s “looking” at a source of voltage at the alternator it is not a true voltage of the system further away due to resistance build up and the “limp lettuce” 12 volts.
I do wonder if your alternator‘s regulator will work as desired if wired as a 3 wire. I don’t think it would and the source for 12 volts is too close to the alternator by the diagram posted earlier on #2 regulator terminal.
Phillip
 

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Your last statement spells out the reason why a 3 wire setup is more efficient than a 1 wire. The built in regulator has to “see” system voltage and when it’s “looking” at a source of voltage at the alternator it is not a true voltage of the system further away due to resistance build up and the “limp lettuce” 12 volts.
Yes, for optimal performance the sense wire should be connected at some central point, such as a firewall distribution block where 12 v battery power feeds the fuse panel and ignition switch. Otherwise your alternator may be fat, dumb, and happy thinking that the system voltage is 14.2 v, when it actually may be only 12-13 volts (or even less) at the fuse panel. That will make for less voltage to the ignition, dimmer lamps and headlights, slower heater fan, etc. However, if you have a modern harness with wiring that is 1-2 gauges larger than stock along with all new connectors, then that loss will be much less significant. For example, an 8 gauge wire feeding the fuse panel, instead 12 gauge.
 
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