affect of leaving head lights on and installing a buzzer

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tim noble
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Joined: Thu Apr 23, 2009 3:56 pm
Location: SE PA

affect of leaving head lights on and installing a buzzer

#1 Post by tim noble »

Again thanks for all the help. The car is a '67 912 in very original condition. I found the path that Jerry suggested and it works fine on fuse 1 and either 6 or 7 but only on the inboard side of the fuse block. I've added some pictures for future reference for early 912 owners. Greg you mentioned fuse 15 - mine has only 12 so you could be referring to a later car.

As a topic related to leaving headlights on - they were on for about an hour while we stopped at a country pub in Chester Co PA. A gentleman in a 2016 Boxter Spyder inquired about the owner of a 912 and a fine looking blond replied that she noticed the car and I chimed in that it was mine. He had reached in and turned them off and hoped I didn't mind touching someones car without permission. Heck no. The woman stated it was a fine example of a soft window Targa and that she knows Porsches well because her uncle was Al Holbert. Pretty cool. Any way it started just fine but half way through the hour + drive home I turned the lights on and it started to backfire and lost power to the extent that I wasn't sure it would make it up a final big hill. Generator light on I turned off the headlights and it returned to normal within a few minutes and generator light went out. The battery measured 10 V when I got home but charged to 12.6 in a short time. One question is - could this have damaged the voltage regulator? I always thought that one could drive with low or no battery once the car is started and that the only drain would be lights or accessories. Why did a low battery cause what was obviously an electrical problem that affected the performance of the engine?
Tim
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Ron LaDow
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Re: affect of leaving head lights on and installing a buzzer

#2 Post by Ron LaDow »

Tim, I'm sure the wiring in a 912 is barely related to that in a 356, so I'd suggest you look here: http://www.912bbs.org/vb/
There's a good bit of cross-over and plenty of folks really knowledgeable regarding 912s (and the year-to-year variables).
Ron LaDow
www.precisionmatters.biz

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tim noble
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Joined: Thu Apr 23, 2009 3:56 pm
Location: SE PA

Re: affect of leaving head lights on and installing a buzzer

#3 Post by tim noble »

Thanks Ron - I did search the 912 bb but there is only one related thread and it did not offer any useful info. I resolved the buzzer by following the logic on the one I installed on my 356. I posted the photo for others future reference as it's as simple as black on inboard fuse 1, red on inboard 7 or other running light fuse. I've actually found this forum more helpful even for 912s. Anyway I am hoping for some insight on why the car ran poorly with a low battery when I turned on the headlights. I'm not thinking this is particular to 912s but to 12 volt cars with a voltage regulator and late 356s fit the bill. It's more of a theoretical question and my concern is that "could it be a symptom of a damaged regulator?" The battery is holding just fine and I haven't driven it since the occurrence because temps have dropped to freezing here in PA. Would testing the regulator with a multi-meter run at 2-3000 rpms tell me it is working properly and what should the output be? Thanks again for any help.
Tim
 

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