I'm posting this on behalf of an old friend of mine: I need to find out exactly how the wiring works for the alternator in an early-'90s GM 3.1L engine. I need to separate the battery sense from the main alternator output for the internal regulator. The alternator has the main output to the battery which is obvious. There is a second two-pin connector with two wires. One goes to the main output of the alternator while the other one goes to the ALT light. What I want to do is have the alternator charge two batteries. I have a two-diode battery isolator, but if I connect it directly between the alternator and battery I will lose voltage because of the diode drop. What I propose to do is to connect the main output of the alternator from the battery to the common lead on the isolator, and then move the sense wire for the alternator to the battery, provided that the wire that currently goes from the two-wire plug on the side of the alternator to the main terminal is indeed the voltage regulator sense wire. Can any of you please tell me if this is indeed the case and whether it will work? Thanks! Dave http://www.roadsters.com/
well first is the voltage drop a real concern? and second if it is check your isolator to see what diodes are used in it , if they are Shottky , the voltage drop on those are half of the regular silicon one, drop of 0.07 to .045 compared to .045 to .07 volts.i would say an way you hook up to the sensing wire directly to the battery ,you would have constant draw or excitement of the regulator as it would sense the battery voltage and that is definetly lower than the output of the alternator because of the wire causing voltage drop, electric efficency is not 100 persent, so if you are looking for an exact replacement of voltage out to voltage in you will not get it
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