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Discussion Starter · #1 ·
I have a 70 firebird and checking for a battery drain over a day or so. The car is pretty much gutted and no lights are on at night. The brake switch has been replaced due to age and not functionality.

Testing/ What I know

If I remove all the fuses from under the dash and check for amp draws in serial from the positive side of the battery with my meter I read .8 amps. if I disconnect the regulator 2 wire clip I read 0 am draw .If I remove the positive wire from the "battery"terminal on the amp I read .8 amps I assume the Alternator is the reason for the drain through the 2 clip wire harness

Note:

Alternator is a chrome 105 amp gm delco

I have 2 wires coming off my alternator "BAT connection. I assume it should of been wired from the starter terminal instead. Can anyone tell me how to correctly wire a starter/alternator circuit. I will browse the web but I think there should not be 12 volts constant at the alternator "B" terminal as an ammeter would not work correctly or should I say it will always be on.

removing all the gremlins from the car going over each circuit one by one..I never drove the car and has been working on it for 2 years
 

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Who ever wired the alt has it wired so alt is on at all times. It's been a while since I worked with that type of alt, so I don't remember which of the 2 wires should be connected to the ignition switch on circuit.

But 1 of the 2 wires needs to have power on it only when ignition switch is on. This wire gives battery voltage to field of alt and voltage regulator. It is known as the exciter voltage. The alt won't put out a charge without the exciter voltage, but this voltage needs to be applied only when ignition switch is in on position.

Not all the time like it's wired now. The 2nd wire of plug in is for idiot light in gauge cluster. With plug in wired correctly, field and voltage regulator only get voltage with key turned on.
 

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Discussion Starter · #3 ·
Thanks Robert,

I was in your neck of the woods last weekend. I bought a house near Darien, GA somewhere in the marsh. Did some fishing and crabbing...

This document helps. I need to move the one wire from the "bat" of the alternator back to the starter. I will check the voltage at the 2 wire plug as I know the alternator worked fine as I disconnected the negative from the battery and the car kept running.. I know this can blow up an alternator

http://www.tuffstuffperformance.com/pdf/1-wire_alternator_instructions.pdf

INSTALLATION To install a 1-wire alternator, disconnect the positive battery cable, unbolt and remove the original alternator, install the new Tuff Stuff 1-wire alternator and re-tension the drive belts. Then simply run one wire from the alternator 'battery' terminal to the positive terminal of the battery or to the starter solenoid main lug, which is connected to the positive battery post. Make sure that the battery is fully charged. Reconnect the positive battery cable, start the engine and using a VOM meter, verify that the alternator is charging at least 13.8 volts @ 1,000 engine RPM's. CORRECT WIRE SIZE IS CRITICAL It is very important to use the correct wire size to connect the alternator to the battery. A wire size too small can allow the wire to overheat, melt the insulation and cause a fire or worse. Depending upon the maximum output of the alternator, use the following chart as a minimum wire size guide. Wire size is based on 4' battery cables. Trunk mounted batteries require heavier gauge battery cables - contact Tech Service for recommendation. One wire alternators eliminate the unsightly factory wiring harness and simplifies installation by using only one wire for charging. NO WARNING LIGHT Note that a 1-wire alternator does NOT permit the use of a charge warning (idiot) light. Most hot rodders and muscle car enthusiasts prefer the use of a volt meter or ammeter to monitor charging. However, certain Tuff Stuff alternators like the 7127, 7139 and 7140 series have terminals that may be used for a warning light. To wire a warning light using one of these alternators, simply remove the terminal plug cover and connect the R (Left terminal, looking from the back of the alternator) to the warning light wire. REQUIRES A GOOD GROUND In order for an alternator to charge properly, an alternator must be grounded to the engine block. If an alternator has paint or clearcoat on the mounting surfaces, it may not be grounded and will not charge. For these reasons, many Tuff Stuff alternators include a grounding tab that should be used to ground the alternator. ROTATION SPEED Alternators spin at approximately 2.5 times that of crankshaft RPM, so an engine at a 700 RPM idle would spin the alternator at 1,750 RPM. Note that the maximum RPM of any Tuff Stuff alternator should not exceed 15,000 RPM's (6,000 engine RPM's). There is no need to worry about use of an underdrive pulley system or an ignition regulator turn on with Tuff Stuff alternators. All Tuff Stuff alternators charge at very low engine RPM's. No other manufacturer in the industry has an alternator that produces more amps at low RPM's than Tuff Stuff.Also note that Tuff Stuff 1-wire alternators are bi-directional and will charge when spun in either direction.

Thanks

Chuck
 

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On the alternator 2 wire clip, the terminals are called T1 and T2.

T1 is the terminal closet terminal to the big post where the "charge wire" that leads down to the starter is, it should go hot only when the key is on, and like said above, it "energizes" the field in the alternator.

T2 is what I call "the sensing wire". It connects into the main hot wire harness of the car. It can sense how much current draw (how many accessories you have turned on), and bumps up the alternator output

to match the electrical demand.

I tried a 1 wire alternator years ago and did not like it. It does not "self adjust" to how much stuff you have turned on. So as you turn on your lights, heater blower fan, electric cooling fans, etc, the volt meter just drops, and

it does not recover in a few seconds like the stock 2 wire alternator because the 1 wire alternator can't sense the electrical demand, I hated it. I think it would be good for a drag car where you don't have any load except for the ignition system just to keep the battery from going dead.
 

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Discussion Starter · #5 ·
Thanks Joe,

I have a 2 wire setup but know nothing about the car as I never had it registered. Its been torn down and brought back up again as I am cleaning every connection possible.

Testing

With the electrical panel fuses removed, the alternator 2 wire clip and "Bat" cables removed, I am reading 105 mA when I connect my meter in series with the negative battery cable and the negative battery post. I assume that this is a bit high and all I have connected is probably the starter and I assume the ignition switch which is always hot. The distributor feed wire has been disconnected as well. I will remove more pieces from the puzzle tomorrow but can anyone tell me what an acceptable draw may be? Tomorrow is another day
 

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On pre computer cars, unless you have a stereo with memory, there should be 0 amp draw with everything turned off. True, components like ign sw, headlight sw, and others get live all the time power to them. But they don't use that power until the switch makes contact.

So maybe one of you live power components has a shorted switch that draws power when switch is in off position. A bulb is burning all the time. Or there's a short in a hot wire somewhere in the car.

Forgot the possibility of a bad diode in alt that's using a little power .
 
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