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Alternator/Battery problem
I have a brand new battery and I just had my Alternator check at Advance Auto Parts and they said it was good. The problem is that my battery drains while the car is running and it is so dead when i cut it off that it will not even turn over. If i wait a while the car will start to turn over but doesnt have enough of a charge left. My lights also go dim and my radio cuts out while driving before it dies.
Please help. 1985.5 late 944
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1985.5 944 na (Black Betty) |
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03-13-2007, 07:59 PM
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What does your car volt meter read when driving ?
Also did they check the voltage regulator built into the alternator? Sox
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"Little problems always come back and bring bigger friends with them". 1986 951"MADDOG" black Dual port WG, 4 port control valve with EBC |
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03-13-2007, 08:10 PM
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They didn't do an extra test on the VM. The gauge stays at 10 volts the whole time.
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1985.5 944 na (Black Betty) |
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03-13-2007, 08:21 PM
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Can you get a meter and check the voltage while you are driving. At the cigarette lighter is a good place. It sounds like the Voltage regulator may be bad (assuming that the alternator test was done right).
This is a test you can try...with the car idling and a meter attached across the battery, take a wooden dowel or a stake about 3 feet long put one end of it on the back of the alternator you can see it from the top. Now tap the other end with a mallet. You may see the voltage on the meter jump a couple of volts. If it does the relay in the VR is sticking. Of course it may be some thing else in the VR or the electronics in the car, but you may be able to narrow it to the VR. Secondly (more complicated), Lift the car (all the stuff about be carefull don't squish your self apply)  With the battery fully charged disconnect the the alternator from below (you will have to remove the pan shields etc. start the car on battery power. and test the out put from the alternator at the alternator it self If the alternator works you should see about 14 volts there if not bad alternator..Good luck Sox.
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"Little problems always come back and bring bigger friends with them". 1986 951"MADDOG" black Dual port WG, 4 port control valve with EBC |
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03-14-2007, 08:07 AM
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Can you get a meter and check the voltage while you are driving. At the cigarette lighter is a good place. It sounds like the Voltage regulator may be bad (assuming that the alternator test was done right).
This is a test you can try...with the car idling and a meter attached across the battery, take a wooden dowel or a stake about 3 feet long put one end of it on the back of the alternator you can see it from the top. Now tap the other end with a mallet. You may see the voltage on the meter jump a couple of volts. If it does the relay in the VR is sticking. Of course it may be some thing else in the VR or the electronics in the car, but you may be able to narrow it to the VR. Secondly (more complicated), Lift the car (all the stuff about be carefull don't squish your self apply) With the battery fully charged disconnect the the alternator from below (you will have to remove the pan shields etc. start the car on battery power. and test the out put from the alternator at the alternator it self with a meter. ( you will have to have a small load on the alternator a 12 volt bulb works) If the alternator works you should see about 14 volts there if not bad alternator. Good luck Sox.
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"Little problems always come back and bring bigger friends with them". 1986 951"MADDOG" black Dual port WG, 4 port control valve with EBC |
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03-14-2007, 08:10 AM
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Thanks for the help . .. I'm going to take the Alt to another place to test it again before I put it back in the car. I have it on jack stands already so better safe than sorry. If the ALT and checks out, what am i looking for on the volt meter? Or does the test at the shop prove that it works? Next is ground wires i guess. . .
wish me luck, i just want to drive to car once.
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1985.5 944 na (Black Betty) |
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03-14-2007, 08:24 AM
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You need to make sure it is putting out 14 or 15 volts. If it is putting out that much under load, but the external volt meter (not the one in the car) shows 10 volts the one of the cars components is drawing too much current. You can start to trouble shoot by pulling the component fuses one at a time and see if on of the components is drawing too much.
Luck Sox Ps. If you take it to a shop (the alternator) make sure they test it with a reasonable load attached to it. Because it may work with no or a small load but fail under larger loads.
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"Little problems always come back and bring bigger friends with them". 1986 951"MADDOG" black Dual port WG, 4 port control valve with EBC |
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03-14-2007, 09:15 AM
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Cars & Coffee Killer
Join Date: Sep 2004
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I had the same issue last year. Mine would read 13.4 volts, and that was low enough to cause problems. (All of my gauges would read low, for example.) I took it to Interstate Batteries and they told me the alternator was fine. I pulled my alternator and got it rebuilt last year and all of my problems miraculously dissappeared.
I would recommend a full rebuild over just replacing the voltage regulator. They replaced the bearings and brushes and it came to around $70 (I bought the voltage regulator separately.)
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Some Porsches long ago...then a wankle... 5 liters of VVT fury now -Chris "There is freedom in risk, just as there is oppression in security." |
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03-14-2007, 11:37 AM
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