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alternator wiring question


Maarten88

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I have got a Nissan 6 cyl in my IIB, and the 24v alternator on it has 4 wires. Two are 'feed' to the batteries, the other ones go to electronical control boxes who control the fuel pump. However, I have decided not to use these boxes but use cable to operate the stop and start function of the pump. Now, I need to wire up the alternator. I presume one wire is for the sense wire, and another would go to the ignition light, if it was a petrol. Can I put either one on a switched postive, in order to give the alternator the signal to start charging?

Kind regards,

Maarten

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"Big" terminal is output, smaller is warning light, connect to ign feed via a 1.2w bulb. Nowadays most alts are machine sensed internally so don't have a sense terminal. If there is another small terminal then thats the sense terminal and connect that via a seperate wire to the battery + for battery sensing. This will allow the alt to take into account the voltgae drop down the wire between its output terminal and the battery.

DO NOT UNDER ANY CIRCUMSTANCES FIT A SWITCH TO THE OUTPUT, SENSE OR WARNING LIGHT TERMINALS, YOU WILL DESTROY THE ALT AS SOON AS THE ENGINE STARTS SPINNING IT!

There may be a 4th terminal marked W which is or a tacho, you can fit a switch to that 1 though, if u want to turn the tacho off.... :unsure:

If the alt has bolts for the output terminal there may be a standard blade connector as well, this is for the suppressor capacitor, connects between blade and earth.

Post a pic of the back of it on here!

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Cheers fro your reply Simon,

I think I have been a bit unclear, for with switched I meant through ignition. Is the light necessary, or can I connect it to + anyway. Althought I have the wiring scheme for my engine, the 2 thin wires from the alternator go into 'black boxes', so I don't know which is which. Therefore, would it hurt to mix them up?

Kind regards,

Maarten

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u need the light to limit the current to the alternator when its not turning. Has to be ignition switched otherwise you will flatten the battery with engine off. Not sure what u mean by black boxes, may be the supressors.. Post pic of back of it on here and will then be able to tell wots wot..

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the charge lamp is more than a lamp; it has resistance that will limit the currenct from alternator to the battery (if you ignore the resistance of the intervening wires.) ~When runningn and charging, the alternator output voltage will be higher thant the battery and connecing by bypassing the lamp would mean much bigger currents would flow. I am not sure what would happen but I would not expect good things = the little lamp is there for a reason. I wouldn't it a LED in its place either but that is snother topic.

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the charge lamp is more than a lamp; it has resistance that will limit the currenct from alternator to the battery (if you ignore the resistance of the intervening wires.) ~When runningn and charging, the alternator output voltage will be higher thant the battery and connecing by bypassing the lamp would mean much bigger currents would flow. I am not sure what would happen but I would not expect good things = the little lamp is there for a reason. I wouldn't it a LED in its place either but that is snother topic.

Yes - the lamp is part of the regulator circuit. Even changing the rating of the bulb will affect battery charging.

On the Metro they suggest two different bulbs, depending when you want the alternator to cut in.

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