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BC77-924
Joined: 06 Jan 2004 Posts: 84 Location: Glacier Park, British Columbia Canada
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Posted: Sat Apr 09, 2005 2:52 am Post subject: How many volts should be battery be charging at?` |
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Help ! How many volts should the system be charging at? I am reading 13 volts with the car running, but I don't think this is quite enough. I have also heard that there are two types of alternators. The exisiting one has just been rebuilt, cleaned and tested with no major issues. I guess otherwise I am chasing down more bad grounds somewhere.
Thanks
D _________________ Silver/Grey 77.5 |
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Johno
Joined: 14 Oct 2003 Posts: 53 Location: Greendale, WI
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Posted: Sat Apr 09, 2005 3:23 am Post subject: |
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I checked mine a week ago as the wire to it broke off and it was also about 13 volts, I have gotten that same reading before and also had it checked at an autoparts house and they said it was fine.
My GM is around 14 if I recall that is why I quesitoned it. I am checking with a VOM at the terminals on the battery. Don't know that it really makes any difference. _________________ 79 924 NA |
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CMXXXI
Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS
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Posted: Sat Apr 09, 2005 4:08 am Post subject: |
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Something in the back of my memory says 14.2v is optimum. I'd venture to guess that anything over 13 and under 15 is OK. _________________ '79 Eurospec 931 |
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AznDrgn
Joined: 03 Nov 2002 Posts: 1188 Location: Harrisonburg/Alexandria, Va
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Posted: Sat Apr 09, 2005 4:41 am Post subject: |
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Check your belt tension. I was always around 13-13.5. American cars tend to charge at a higher voltage for some reason while most europeans I've seen do fine charging at around 13.5. From what I've seen working at a parts store if you have an american car chargin in the 13's there is something wrong or the alternator is about to fail. _________________ -'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers
-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Sat Apr 09, 2005 6:05 am Post subject: |
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My volt meter gauge reads out at a hair under 14 under normal driving conditions. It's closer to 13.5 when I have headlights and foglights on. My alternator is a rebuilt Bosch with less than 1K miles on it. _________________ erstwhile owner of just about every 924 variant ever made |
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Smoothie
Joined: 01 Jan 2003 Posts: 8032 Location: DE (the one near MD, PA, NJ)
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Posted: Sat Apr 09, 2005 7:21 am Post subject: |
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My old 75 amp Bosch sometimes gave readings down below 12V (idling, at night, headlights on, stereo on, HVAC fan and radiator fan/s on). I was also replacing the battery every 2-4 years around then. I started looking into an alternator upgrade and decided on a 140 amp Delco. My last battery change was a new DieHard in May'98 and the Delco alt went in sometime in 2001, so that was a 2-3 year old battery already at the time the new alt went in. That battery's still going strong now just shy of 7 years later and I'm pretty sure the alternator's got a lot to do with it, but I don't know...maybe a rebuilt Bosch would have had a similar effect. In any case, that's a quick-easy test - monitor your voltage (I did it with a multimeter hooked-up at the cigarette lighter) and see how low the voltage dips when you're idling with headlights and everything else on. If it drops below 12V, something's not right. With the alternator upgrade the lowest I get now with everything electrical switched on is approx. 12.8V. _________________ "..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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Smoothie
Joined: 01 Jan 2003 Posts: 8032 Location: DE (the one near MD, PA, NJ)
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Posted: Sat Nov 12, 2005 10:44 am Post subject: |
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R.I.P. I finally killed that old Diehard battery. Yesterday it was suddenly dead as a rock. The day before, it was fine with no noticable signs of impending doom. At 7.5 years, I think that's the record holder for me. It would have gone longer for sure, but I put the "Pre-Luber" elect. oil pump back into service earlier this year which runs on battery power before engine startup and then for a few minutes again after shutdown. _________________ "..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Sun Nov 13, 2005 1:25 am Post subject: |
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i have this problem...when car is runing i get 12V at most !
and if the car is off...and i turn it on it wont charge unless i give it a pedal to go over 3500RPM then the charging stars....this is realy anoying....any ideeas ? _________________ https://www.the924.com |
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Smoothie
Joined: 01 Jan 2003 Posts: 8032 Location: DE (the one near MD, PA, NJ)
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Posted: Sun Nov 13, 2005 2:13 am Post subject: |
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<12V isn't good. I'd guess your batteries don't/won't last as long as they should.
If you've already been through the grounds and battery-starter-alternator wiring, your problem's probably either that the alternator's old and tired and/or you have too much current drain by added components - it's also conceivable that the voltage regulator's in need of replacing. Personaly, if it's an alternator problem, I like the idea of replacing with a higher amperage version. The Delco CS-144 (140 amp) could be adapted to use on an NA, but you'd have to fabricate your own bracket to do it. An alternator shop can alter the Bosch 75 amp to put out approx 90-95 amp, but for the cost, that's not much of an improvement.
I'd start by double checking the wiring and remember to check the grounding between alternator and engine.
Also - Does your dashboard alternator light come on when you turn the key to ignition-on before starting the engine? _________________ "..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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flosho
Joined: 01 Jul 2004 Posts: 3155 Location: Eau Claire, Wisconsin
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Posted: Sun Nov 13, 2005 2:21 am Post subject: |
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morghen wrote: | i have this problem...when car is runing i get 12V at most !
and if the car is off...and i turn it on it wont charge unless i give it a pedal to go over 3500RPM then the charging stars....this is realy anoying....any ideeas ? |
I recently had the same problem, after swapping out the alt, it did the same thing. Turns out, there was no ground strap on my alternator.. It wasn't on there before I took the old one off! I had been running my car for a year without the ground strap, which is why this is the third alt, and 2nd battery. So I just used some amp power wire and made my own. Check and make sure that you have an earth strap grounded from the back of the alt to the manifold.
Thats assuming its similar to 931's set up..? _________________ [This Space For Rent] |
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Ozzie
Joined: 12 Mar 2005 Posts: 4448 Location: Townsville, Qld. Australia
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Posted: Sun Nov 13, 2005 6:47 am Post subject: |
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If that doesn't work pull the alternator and replace the regulator.
Its the black box on the back held on by 2 screws.
Replacement is about $30.
It contains the brush gear and regulates the voltage. _________________ Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Sun Nov 13, 2005 7:45 am Post subject: |
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i will check the wires tho i remember doing that before...where can i find a diagram of the exact wires ?
i did replace the regulator...same shit....and the grounding...well...the bushings the alternator uses to stay on the engine were caput when i bought the car so i had them made from iron.
yea the red light comes on when i turn the key... _________________ https://www.the924.com |
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Smoothie
Joined: 01 Jan 2003 Posts: 8032 Location: DE (the one near MD, PA, NJ)
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Posted: Sun Nov 13, 2005 8:23 am Post subject: |
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morghen wrote: | yea the red light comes on when i turn the key... |
Ok then, there's apparently nothing wrong with the bulb or exciter wire.
If the alt-engine ground is good and a new regulator didn't fix it, your left with either bad battery post and/or starter connections or possibly a worn alternator and/or unusually high current draw. Just for fun though, I'd run a temporary jumper from alternator casing to engine or chassis ground (or to battery(-)) with something hefty like a battery jumper cable.
Wouldn't be a loose belt, would it?
The 931 alternator depends on there being a good connection at the starter (batt-starter and alt-starter wires meet there), but I'm not familiar with the 924NA wiring arrangement - someone else would have to fill you in on that.
Yet another possibility is a bad battery with high internal resistance... Will the battery take and hold a charge up over 12V if put on a battery charger? _________________ "..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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