So, it came in the bundle of boxes (the alternator that is) when I bought the car and it appears to be a bosh unit . When I restored the car my logic was ,well I don't really know if the alternator is a newer unit with the regulator built in or not so what's the harm with putting a regulator on the main circuit board. I did and all was well. Sat at about 13.5V at idle and would go to about 14.5V at speed. So driving down the 101 highway I happened to look down at the voltage and it was pegged at 16. Pulled over and yanked the board mounted regulator. Fired the car back up and it was at 14 and then settled down to about 12.0V - 12.5V now where it will just stay.... at any RPM. When I turn the lights on it dips to about 11.0V - 11.5V.
Not enough I'm thinking so I put the old board mounted regulator back in. Fired it up and at idle it was 13.5V again. Ripped down the road a few miles and it @14.0V - 14.5V AGAIN. Then Pow.... pegged 16+ Put the lights on and 14.5V. Hit the brakes and @13.5V.
Drove home (just a few minutes) and at that idle with voltage saying 15V now I took my FLUKE and hit the battery. Spot on 15.0V so my gauge is true.
What the heck?? Anyone have any thoughts?
Full Version: Weird alternator issues
I ended up ditching the relay board/regulator/alternator when I did my swap when I first got my teener so it's a bit out of my realm of familiarity, is it possible that the regulator is worn and/or getting affected by temperature?
How many wires go to/plug into the alternator?
How many wires go to/plug into the alternator?
QUOTE(lierofox @ Jun 3 2019, 01:12 PM) 
I ended up ditching the relay board/regulator/alternator when I did my swap when I first got my teener so it's a bit out of my realm of familiarity, is it possible that the regulator is worn and/or getting affected by temperature?
How many wires go to/plug into the alternator?
The board regulator is brand new but hey...been down this road before. Especially with those relays that are not made in Germany but that's another story.
Dave
Your altenator is fine you just have no control of its output,replace your voltage regulator and you should be fine ,don't buy the made in China Hella one because they don't fit properly..ask me how I know 
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Only other thing that's coming to mind is if the connections on the relay board (either at the regulator, or where the alternator harness plugs into it) are corroded or otherwise have high resistance, would that cause the regulator to sense an incorrect, lower voltage between the D+ and D- terminals and as a result send too much current through the field windings on the DF terminal to bump up the voltage?
I mention that because thinking back that actually was a problem I had with my alternator as well in my swap because of a bonehead mistake I made. Instead of grabbing the voltage signal at the battery, I was grabbing it from another circuit that came on with the key. The resistance through my old fusebox and load on that circuit of the wire I tapped in to caused the voltage to drop by about 1.5-2 volts by the time it reached where I spliced in, so the alternator saw less voltage than it wanted and bumped up its output to compensate. Instead of charging at 13.7 volts it was charging at 15.2-15.7 volts. That's a Subaru alternator though. Not fully familiar with the operation of the 914's stock alternator.
But, since it's easy to get to, maybe pop off the regulator and alternator connectors on the relay board and make sure the spade terminals are all clean, tight, and making good contact?
I mention that because thinking back that actually was a problem I had with my alternator as well in my swap because of a bonehead mistake I made. Instead of grabbing the voltage signal at the battery, I was grabbing it from another circuit that came on with the key. The resistance through my old fusebox and load on that circuit of the wire I tapped in to caused the voltage to drop by about 1.5-2 volts by the time it reached where I spliced in, so the alternator saw less voltage than it wanted and bumped up its output to compensate. Instead of charging at 13.7 volts it was charging at 15.2-15.7 volts. That's a Subaru alternator though. Not fully familiar with the operation of the 914's stock alternator.
But, since it's easy to get to, maybe pop off the regulator and alternator connectors on the relay board and make sure the spade terminals are all clean, tight, and making good contact?
QUOTE(porschetub @ Jun 3 2019, 01:59 PM)
Your altenator is fine you just have no control of its output,replace your voltage regulator and you should be fine ,don't buy the made in China Hella one because they don't fit properly..ask me how I know
.Yeah that would seem logical. The damn regulator I bought is also a tad large as the plastic top to the relay board will not fit correctly with it in place. I have several ORIGINAL used ones on there way for me to try. Hoping that takes care of it. Just pisses me off as I just bought that damn regulator a couple months ago.
QUOTE(lierofox @ Jun 3 2019, 03:56 PM)
Only other thing that's coming to mind is if the connections on the relay board (either at the regulator, or where the alternator harness plugs into it) are corroded or otherwise have high resistance, would that cause the regulator to sense an incorrect, lower voltage between the D+ and D- terminals and as a result send too much current through the field windings on the DF terminal to bump up the voltage?
I mention that because thinking back that actually was a problem I had with my alternator as well in my swap because of a bonehead mistake I made. Instead of grabbing the voltage signal at the battery, I was grabbing it from another circuit that came on with the key. The resistance through my old fusebox and load on that circuit of the wire I tapped in to caused the voltage to drop by about 1.5-2 volts by the time it reached where I spliced in, so the alternator saw less voltage than it wanted and bumped up its output to compensate. Instead of charging at 13.7 volts it was charging at 15.2-15.7 volts. That's a Subaru alternator though. Not fully familiar with the operation of the 914's stock alternator.
But, since it's easy to get to, maybe pop off the regulator and alternator connectors on the relay board and make sure the spade terminals are all clean, tight, and making good contact?
All connectors / wiring harness are either brand new and or cleaned and looking new. Brand new regulator but that does not mean#$*&$# anymore. I completely removed all of the black tar crap on the bottom side of the relay board and had the contacts completely cleaned and all solder joints checked. Currently have a foam board that fits snug up under that relay and I check it now and again and it's dry and looking new several months after doing all that.
You need a new voltage regulator. In my experience they can be unreliable and I carried a spare for a long time. Eventually I went to an adjustable regulator sold by a Volvo guy.
A stock alternator has a 3 pole plug just like the one on the board. A internally regulated alternator just needs battery (B+) and the charge light, which can be marked 61. Sounds like a bad voltage regulator.
Just a WAG. Sounds like you have a grounding problem between the alternator and the engine case./
16V means your alternator was putting full output to the battery. No bueno.
12.0-12.5V means all you had was the battery. No bueno again. But that makes sense for having no VR plugged into the unregulated stock alternator. (Might also make sense for a regulated alternator, but I don't really know.)
You do need a voltage regulator, but you need one that works.
--DD
12.0-12.5V means all you had was the battery. No bueno again. But that makes sense for having no VR plugged into the unregulated stock alternator. (Might also make sense for a regulated alternator, but I don't really know.)
You do need a voltage regulator, but you need one that works.
--DD
[quote name='Dave_Darling' d 
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
[quote name='worn' date='Jun 4 2019, 05:54 PM' post='2719726']
[quote name='Dave_Darling' d
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
[/quote]
Just got 4 used/original regulators from Big Al (Parts Heaven) to try. If I can find two that work I will keep one as a spare. I will clean them up and pop them in tomorrow and report back my findings. Fingers crossed.
Dave
[quote name='Dave_Darling' d
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
[/quote]
Just got 4 used/original regulators from Big Al (Parts Heaven) to try. If I can find two that work I will keep one as a spare. I will clean them up and pop them in tomorrow and report back my findings. Fingers crossed.
Dave
[quote name='Downerman' date='Jun 4 2019, 08:27 PM' post='2719771']
[quote name='worn' date='Jun 4 2019, 05:54 PM' post='2719726']
[quote name='Dave_Darling' d
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
[/quote]
Just got 4 used/original regulators from Big Al (Parts Heaven) to try. If I can find two that work I will keep one as a spare. I will clean them up and pop them in tomorrow and report back my findings. Fingers crossed.
Dave
[/quote]
OK..... the first of the four used regulators did exactly what my New (Bad unit) did and I was thinking "oh great...bigger issue here". Popped the second unit in and Bata bing.... were golden. Idles @ 13V and at full speed it @ 14V. Took it for a nice 30 minute ride and it never changed. Tried the third unit and it was also good..... my spare. Didn't even try number 4. Life is good. Thank you all for the comments and support.
[quote name='worn' date='Jun 4 2019, 05:54 PM' post='2719726']
[quote name='Dave_Darling' d
You do need a voltage regulator, but you need one that works.
--DD
[/quote]
[/quote]
Just got 4 used/original regulators from Big Al (Parts Heaven) to try. If I can find two that work I will keep one as a spare. I will clean them up and pop them in tomorrow and report back my findings. Fingers crossed.
Dave
[/quote]
OK..... the first of the four used regulators did exactly what my New (Bad unit) did and I was thinking "oh great...bigger issue here". Popped the second unit in and Bata bing.... were golden. Idles @ 13V and at full speed it @ 14V. Took it for a nice 30 minute ride and it never changed. Tried the third unit and it was also good..... my spare. Didn't even try number 4. Life is good. Thank you all for the comments and support.
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