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Sinister
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Everything posted by Sinister
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The problem is determining what section of the cable. Rewiring would also be a PITA. Would a bad cable do that when it warms then? I will try to run a direct cable, and maybe attach it to the VMM to see if there is any Vrop. Likely thre would be, but back to what section of the cable is the culprit.
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Well, when the voltage drops to 12.8 at the battery, the alternator STILL sees 13.5, so that rules out the alternator breaking down when it gets warm. What happens is that the difference between the alternator and battery becomes larger as the car gets warmer, eventually stopping at 12.6-12.8. If I find a device that is drawing to much power, what next? Have you tested your voltage? To see how different mine is from yours? I dount it would be a device, seeing as how increase in voltage drop is directly proportional to warming up... When I rev it, I do hold it there for a bit, but not 10 minutes, maybe 15-30 seconds. Let me know.
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I have found no loose, dirty, corroded, broken, worn connections/wires. Not sure where esle to look. Which fuses for what devices should I look for? When I rev, nothing changes. What does that point to?
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When I key on voltage does not drop much. What you say about the connection heating up makes sense, but the only place I have yet to look would be the main fuse and junction box, behind the dash. AM I looking necessarily for a LOOSE connection or could there be some other sort of issue? As for fuses, what am I looking for? Regardless, seeing as how the voltage drops as the car heats up, must be the fisrt option above. I did not understand part of your first post above, which said to dry to draw current thoguh it. I thought that is what a voltage drop test is? What does you voltage read at the battery when the car gets warm, measured with a DMM, and what does it read at the alternator?
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There is no loss with the car off, so I don't think measuring resistance will not work to detect the issue, which is why I am doing the voltage drop tests. There are only two main grounds, the one at the batter and the one from the engine. Since the voltage drop from the alternator chassis to the vehicle chassis is only 0.1, I believe that is not the problem. The main issue is that when the car is cold, it is fine. As the car gets warmer, the voltage starts dropping. My alternator never gets below 13.4-13.5, but at that time the battery voltage is 12.8 or so, so that is the issue. It can't be normal to have the voltage at the battery drop that low to the point it is not charging...
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How does one test for example at the starter, with the engine on? It is too hot and hard to get in there with the car on. As per the diagrams, to check the distribution box and main fuse, one would have to pull the dash...there would be no choice.
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I've tested the main ground at the alternator, the alternator to chassis and the battery. I have tested the alternator positive cable and the battery positive and the positive form the firewall. Would you then recommend taking apart the dash to thest the main power fuses and the connection to the firewall from within? Where else should i check? How come the current drop appears to happen when the car is warm, and especialy when the 2nd fan speed for the front fans kick in? Could it simply be that the fans are draining too much current? What does everyone elses voltage drop to with the high speed fans on? What is the normal current drop between alternator and the battery? There is no drop when measuing with the car off and measuing batetry voltage at the battery and at the alternator.
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Mine starts out at 13.5 and eventually goes lower. It has nothing to do with the car not running long enough in this case, as the voltage with ac on eventually drops to 12.8 at the battery and 13.5 at the back. That menas the battery os not charging at all. Not sure why I never see the 14. Where am I loosing current? I've run out of ideas.
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Updates: Voltage-drop tested between alternator houring and chassis. 0.12 loss. Between battery post and wire: 0 loss. Bewteen battery ground wire and chassis: 0 loss. I htink this menas that a ground is not my issue? This rules out having to test the large ground from the engine to the chassis in the rear. Drop tested between positive post and cable, at battery: 0 loss. Between cable and firewall: 0 loss. Another thing that puzzles me is that the warmer the car, the more I lose. In the morning it is about 13.5 in the rear and 13.2 up front. By the end of the day, it was the same in the rear, but 12.60 up front (basically battery voltage). If I turen off the AC, it goes up to 13.2 up front. This happens everyday and has happened since the car was purchased originally. What would cause tmperature to matter? Why do I never (except last Sunday, when I had just charged the battery, with a a battery charger) do I get 14.1 volts (in the rear, but 13.8 up front). As the car was started to days later, I no longer saw those numbers. That is the only time I have seen anything close to 14 on this car. If it is relevant, ai 3k rpms I have what sounds like a bad ground, but it does not come from the stereo. But it could be the turbos or something...
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Should the voltage at the alternator still not be 14.1 or so? I did remove and sand the negative terminal at the battery and to the chassis at the battery end, as well as the positive cable at the battery (but not to the firewall, as it seems to have a security nut holding it. I did remove and visually check all of the other grounds, but I guess I'll be jacking the car up and sanding the groud straps that I find. Any connections you suggest for me to check specifically? Since the voltage at the wire that comes out of the alternator (the red one) I am assuing the loss must be somewhere between the back of the car and the trunk in front, where the battery is? Also, what is the best way to check for voltage drops?
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Hi! They loaded it up on a machine. As for parasitic drain, even if the car is not driven for a week or sometimes more, it will still start just fine. Not sure of if that means anything. How do you connect it in series in this case, to check?
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Ever since I purchased my 2001 996 TT, whenever one measures voltage at the battery, engine started, I get 13.2V with everyting off but the engine running, 12.94V with AC on, and 12.88V with headlights, radio, AC, etc. on. With many short trips, my battery eventually disharges, requiring a full recharge about every 8-10 months, with a battery charger. This weekend I fully charged the battery and when I measured the voltgage at the battery, with the engine running, it measured 14.1V. When I went to drive the car, it automatically droped to 13.4, then 13.2, and now it is back to 12.8V. When measuring at the alternator end, voltage is 13.5-13.6. I removed the alternator and took it to an alternator shop. On the test bank, it puts out 14.2V, so alternator and regulator are OK. So as is now, the car tends to read a voltage of 12.88 at the battery end, and 13.5 at the alternator end. With the car off, the voltage on both ends (battery and alternator end) is 12.46V. Am I losing current? All my grounds are tight, and the battery tests fine.