Re: Volvo 12v alternator
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So here’s a couple of things that we learned about the alternator systems on the Volvo. Our original problem was that the 24 V alternator was not charging until fairly high rpm above 1800. Ultimately what we determine was that the warning light on the 24 v panel in the main salon was burned out therefore not completing the exciter circuit. When replaced by a new indicator light the 24 V system behaved properly.
During troubleshooting we noticed the yellow wire on the 12 V alternator was disconnected. It must’ve happened recently because the 12 V alternator was not putting out any voltage today but we didn’t have a problem with the battery in the past several weeks.. The battery was down to 12.4 V. Interestingly the tachometer did not work either, Which makes sense since it’s connected with the black and gray wire to the alternator picking up the unrectified voltage to pace the RPM.
Turns out that the yellow wire should have been and perhaps was attached to a tab on the main positive lug on the alternator to the battery. That yellow wire appears to feed the 12 V voltage regulator.
Anyway, with the 24 V warning light replaced and the yellow wire connected to the positive lug on the 12 V alternator everything is working great. Thank you all for your input. Note that the above is our rationalization for what happened and may not necessarily be 100% correct.
On Oct 27, 2020, at 1:56 PM, CW Bill Rouse <brouse@...> wrote: