aternator wire diagram?

[deamon3]

I'm trying to modify a first gen alternator to produce electricity constantly. It's for a little project I'm working on. Keep in mind it's not actually in an explorer.

I'm just trying to figure out how to connect the cable to it so any time it's spinning it will send out electricity. And I'm not entirely sure what all the connections do , or where to connect my output wires to.

 

[Common Cents]

I'm trying to modify a first gen alternator to produce electricity constantly. It's for a little project I'm working on. Keep in mind it's not actually in an explorer.

I'm just trying to figure out how to connect the cable to it so any time it's spinning it will send out electricity. And I'm not entirely sure what all the connections do , or where to connect my output wires to.

It's not nearly as simple as you might think.

You will need both a battery (12 volt, preferrably lead acid type, though it can be a small one like for a lawn tractor or motorcycle) and the alternator.

You have to provide voltage to the "exciter" wire(s). If that wire isn't energized with voltage, there will be no output from the main output wire because there will be no magnetic field in the alternator.

Also, the battery provides a load for the alternator and prevents burning out the diode in the regulator section or the voltage regulator itself.

There's only one wire you don't need to connect, and that's the wire that goes to the light in the instrument cluster. That wire will provide ground to an indicator lamp which will light in the event that something in the alternator fails and it is no longer producing any output. The other side of the lamp goes to the positive leads from the battery and the main alternator output.

I did find this diagram for a 1998 Explorer:

1998 Ford Explorer Charging System

 

[deamon3]

So which wire is the exciter wire on the first gen alternator? Also , could I just connect the output of the alternator straight to the exciter wire? So supposedly I would only need the battery to start it but afterward the alternator should stay on?

 

[Maniak]

Just a tidbit. on the 1st gens, if the Charge bulb is not connected or burned out the alternator wont' charge. It uses that wire through the bulb to start the charge.

Dannyboy ran into this years ago when he built his own dash and tried to skip hooking up the alternator bulb.

~Mark

 

[deamon3]

So supposedly this is the diagram for a 94 , which means the green and yellow wires I should tie into the battery's positive , and the two white wires get connected to each other? Then the whole alternator is the ground and the large positive terminal is the positive?

 

[Common Cents]

So supposedly this is the diagram for a 94 , which means the green and yellow wires I should tie into the battery's positive , and the two white wires get connected to each other? Then the whole alternator is the ground and the large positive terminal is the positive?

Yes, you are mostly correct for all those wires. The light green/yellow wire is the input to the regulator (which I somewhat incorrectly called the "exciter" wire). It should have a 512 ohm resistor between it and the battery. The light bulb itself is optional, but it will act as a warning light to tell you if the thing isn't working and isn't making current.

The large positive terminal also needs to be connected (permanently) to the battery as well. If there isn't a connection from that terminal to the light green wire, the regulator isn't regulating the output of the alternator based on the battery condition and the load, it's setting the output based on the battery you have connected to the light green wire. This will result in uncontrolled output at the big output terminal as the battery attached to the light green regulator input discharges and the regulator steps up the output current trying to charge it.

Note the location of the battery in that diagram. It isn't really clear, but that "hot at all times" input on the light green/yellow wire circuit is connected to the positive battery terminal. The light green wire is a "feedback loop." It must connect to the output of the alternator (the big post) and the battery for things to work properly. This adjusts output from the big terminal in response to load and battery condition.

It's best to think of the "Alternator" in a modern car as a smart battery charger or "battery tender" with a mechanical input at the pulley. It is designed to keep the battery charged, and the battery is an important part of the overall circuit. All of the circuitry for the charging function is built into the regulator. It uses the battery voltage as a control input for feedback to the regulator, which controls alternator output by adjusting the voltage/current to the field coil. When the battery discharges, the output of the alternator goes up to recharge it. When it's running in a steady state, it will reach an equilibrium point where the battery is fully charged and the "load" (everything electrical in the vehicle that is turned on) is actually being powered by the alternator output. But the entire feedback system that regulates the alternator output is centered on the battery.

If you remove the battery after you spin the thing up, you are very likely to burn out the diode shown in the regulator, resulting in either an uncontrolled output (excessive voltage) or no output at all.

You can use a $25 or cheaper garden tractor battery in the circuit and it will work just fine. But there has to be a battery in the thing while it's running, or it probably won't work properly.

"Won't work properly" could mean it stops generating electricity. It could also mean voltage rises uncontrollably and you have 50-80 volts (or more) at the big terminal. It could also mean the diode in the regulator secition gets fried and everything stops working. The results will be unpredictable, but it won't work as you expect.

 

[Roadrunner777]

Just a tidbit. on the 1st gens, if the Charge bulb is not connected or burned out the alternator wont' charge. It uses that wire through the bulb to start the charge.

Dannyboy ran into this years ago when he built his own dash and tried to skip hooking up the alternator bulb.

~Mark

I just renewed my elite status, and this is an example of why I am so comfortable INVESTING that money. You will not find this little factoid in Chiltons, or even the factory manuals. It was learned the hard way by another member. The odds are tangible that this bulb will burn out in an 18 year old truck. If you did not know this, you may well replace a perfectly good alternator. I wish there was a factoid hall of fame for this kind of stuff... it's going to sink into oblivion again, but it's going in my personal permanent notes.

Hey, thanks!

 

[deamon3]

If you did not know this, you may well replace a perfectly good alternator.

It's for a little project I'm working on. Keep in mind it's not actually in an explorer.

don't worry it's not for my truck.

But thanks for all the excelent info so far gents it really helps out!

I have another question. Whats a GOOD brand of power inverter? Also , how powerful should it be to run a 1hp electric motor? I was thinking 3000w.

 

[Maniak]

don't worry it's not for my truck.

But thanks for all the excelent info so far gents it really helps out!

I have another question. Whats a GOOD brand of power inverter? Also , how powerful should it be to run a 1hp electric motor? I was thinking 3000w.

I can answer part of that. My 1 hp Goulds Jet pump pulls 6-7 amps at 120Volts while running. Startup is much higher (too hard to read on the meter).. If possible, Get something that runs a true sine wave instead of square wave. Those cost a bunch more but the power is much cleaner..

I was able to run (including startup surge) the 1 hp pump on a 2500 watt generator..

~Mark

 

[Roadrunner777]

1 HP = 750 Watts. Double that just because you don't want to run an inverter maxed out, so call it a 1500W inverter. A good 1500W inverter will give you 3000W peak to deal with motor start. You can get modified sine wave inverters good enough for motors at these ratings for $300 or less. I'd look at warranties and stuff to make a decision.

 

[Common Cents]

don't worry it's not for my truck.

But thanks for all the excelent info so far gents it really helps out!

I have another question. Whats a GOOD brand of power inverter? Also , how powerful should it be to run a 1hp electric motor? I was thinking 3000w.

Why run an alternator (from a mechanicle source) and then use the output from that to power an inverter and plug a motor into it?

A belt/pulley system would be far more efficient. Or a gear setup.

You'll have losses in the alternator (probably 85% efficient turning mechanical energy into electricity), losses in the inverter (probably 80% efficient again), and losses in the motor.

Or is the inverter/motor combination completely unrelated to the project with the alternator?

 

[Roadrunner777]

I'm assuming you are not running this inverter off your truck, you sort of said that. If you are, the alternator is obviously not going to keep up. Runtime on the motor will be quite limited, based on the state of your battery. Regarding inefficiencies, yes, lots of losses there. My question is if you can adapt an old starter motor to the task? Cheaper and less complicated if it is possible.

 

[Maniak]

From what I'm reading, we are making an inverter style generator...

Gas motor turning an alternator to power an inverter to run a pump...

Newer/quiet generators are actually just big inverters with an alternators and their power is normally cleaner than the other type of generators. I don't know if they have a more efficient or a pure sine wave inverter though.

~Mark

 

[Roadrunner777]

connect pump to motor? obviously not, just... hey, details on the application???

 

[deamon3]

From what I'm reading, we are making an inverter style generator...

Gas motor turning an alternator to power an inverter to run a pump...

? dont think I mentioned that anywhere lol.

Another question , do higher amperage alternators require more power to rotate them then lower amperage ones? For example a 100amp vs a 220amp? is it that the alternator simply generates more power from the same amount of rotational power? or that both the output and the rotational power required are higher?

 

[deamon3]

Oh an thanks for the info so far on the inverter that helps!

 

[Maniak]

? dont think I mentioned that anywhere lol.

Nope, but from the questions and some info from other posts it sounds like what I was working on which is the gas motor to run an alternator to power the water pump via an interver when the power is out.

We can handle no power for most things, but no water when there is no power is annoying..

~Mark

 

[Roadrunner777]

An alternator simply converts motion to electrical energy. If you have a load of 200 Watts, then the torque is the roughly the same whether the alternator is 500W or 10,000 Watt capacity.

And, torque will be proportional to load. To the physicists out there, yes, torque is not really the right term. I'm using it to differentiate between physical and electrical power. 1 horsepower is about 750W, less losses due to magnetics, friction, heat, etc...

Oh, also, a much larger alternator may require more power to initially spin up.

I hope I answered your question, I was not quite sure what you were asking, so I sort of covered all the bases, I hope. If I missed, give me smaller simpler questions and I will see if I can help.

 

[Common Cents]

? dont think I mentioned that anywhere lol.

Another question , do higher amperage alternators require more power to rotate them then lower amperage ones? For example a 100amp vs a 220amp? is it that the alternator simply generates more power from the same amount of rotational power? or that both the output and the rotational power required are higher?

How much work or power is required to turn the shaft depends on how many amps are being drawn from the alternator. If the battery is fully charged, or charged over the voltage that the regulator will charge to, then the regulator will not put much energy in the field coils. There will be very little rotational resistance, and very little current will flow in the output circuit.

If there is a heavy load on the system, the regulator will provide more current to the field coils. This will increase the power required to turn the shaft, and it will increase the current output at the alternator output terminal. Typically, the voltage regulator is set to charge to ~13.8 volts give or take a couple tenths of a volt.

For an 80 amp alternator, operating at full capacity of 80 amps, it usually takes about 1.8hp to 2hp to keep the thing spinning. If you have a 200 amp alternator operating a system where it's spinning at a constant speed, and there is a constant 80 amp load on the system, it will eventually balance out at an equilibrium where the alternator is making the required 80 amps and will take the same 1.8hp to 2hp to keep it spinning. If the 200 amp alternator is put in a system with a severely discharged battery, or with a 200 amp constant load, it will operate at 200 amps, and that will increase the power requirements to somewhere around 4.5 hp to keep the thing spinning.

If either the 80 amp alternator or the 200 amp alternator is connected to a battery which is fully charged (say maybe 14 volts, just above the 13.8 volts that the regulator has set as it's full charge target), then the regulator won't send much (any) current to the field coils, and the alternator will freewheel and make no current. At that point, you still need some power to keep it spinning to overcome friction in the bearings and in the belt/pulley system. But there will be no power required above that by the load of the alternator itself.

Generally speaking, amps * volts = power in watts, and you can convert that to horsepower by dividing watts by about 750. Actually, since there are always inefficiencies and losses, you'll probably get a better result dividing watts by about 600 (assuming about an 80% efficiency, with 20% losses to friction, interal resistance and "waste" heat).

Actually, Google will do the calculations and conversions for you, with the exact conversion factor. For example, 750 watts in hp will show you that the 750 watts is an approximation, and show exactly how many hp 750 watts equates to. You could go the other way, too, 1 hp in watts will give the actual conversion factor of 745.699872 watts = 1 hp.