Join Date: Jul 2008
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Re: Alternator for Volvo MD2030
The voltage sense wire senses the voltage of the battery. In the Valeo alternator, it is assumed that the battery voltage on the positive terminal represents the real voltage of the battery. This is rarely true. You can simply unclip it from the alternator post and lead it straight to your battery for better accuracy.
Alternately (or in addition), you can put a diode in-line with it and use its voltage drop to trick the alternator into providing higher voltage and more current than it would normally while charging.
Thanks Mark... Just to confirm, the yellow wire in this pic is the voltage sense wire, correct? The red wire you see is very short and leads to the lug on the starter motor where the cable from the battery connects, so that squares with what you said.