High Output Alternator

Discussion in 'General Station Wagon Discussions' started by Paladin62, Aug 22, 2022.

  1. Paladin62

    Paladin62 Well-Known Member

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    After I installed Vintage Air, a radiator fan and fog lights I went to an alternator shop and paid almost $200 for a 140 amp alternator. It never lived up to it's billing. If I turned on the fog lights or the radiator fan, my output fell below 12 volts. Believing the alternator was not the problem I searched for other causes.

    After no improvement, I took it back only to be reassured that it was "OK".

    I decided to replace the unit. I settled on a 120 amp unit sold at O'Reillys ($120). It was a bit of a challenge since the prior alt was 6 1/2 inches from the upper bolt hole to the lower and the replacement unit was 7 1/2 inches. I ended up changing out the upper "adjusting" bracket which cost $20.

    Now I have power to spare!!
    20220821_183028.jpg 20220821_180251.jpg 20220822_190419.jpg 20220822_214257.jpg
     
  2. OrthmannJ

    OrthmannJ Always looking for old ford crew cabs

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    Very nice. Better to have extra power as opposed to not enough.
     
  3. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    It sounds like it would experience a circuit open somewhere under full load in the underhood heat. I've had windings, diode bridges and regulators do that, just on GM and Ford internal regulator alternators.
     
  4. Paladin62

    Paladin62 Well-Known Member

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    Well, well well... The alternator was putting out more than enough for my needs...problem was, when you turn off the ignition, the motor kept running. The answer is an Anti-feedback diode. That was easy to get but when you add it to the circuit...the power drops significantly.

    I went on the internet looking for a solution. The only thing I found was a short response on a forum that said "cut the exciter wire at the fuse box and hook it to the accessory side of the ignition switch"

    The exciter wire, (white one) works like this, when the key is switched on, it tells the alternator the ign switch is live and ready. Current flows to the alternator, tells the regulator it's ready to accept a charge, start engine, power flows the opposite direction back to the switch. The ign switch inside is separated from the run side, meaning acc is it's own circuit, when switched off, the acc side is dead and doesn't allow current to flow through the switch. If you hook the exciter wire to the run side, the engine will run on after shutting the ign switch off because it'll bypass inside the switch and not shut off. Clear as mud?


    Electricity is not my strong suit. Anyone able to give me more detailed guidance?
     
    Last edited: Aug 27, 2022

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