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Capacitor or no?
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<blockquote data-quote="chris229" data-source="post: 83139" data-attributes="member: 542614"><p>guys----------- looks like BIGBASSMAN has use a graph show the uselessnes of big ESR caps and the 200A load is to show that the high ESR kills the design</p><p></p><p>RC text------</p><p></p><p>Lesson 8</p><p></p><p>For this lesson I have done some actual measurements. Here are the test conditions: To measure voltage we used an Audio Precision with a DCX module. It is accurate to three decimal places. For sample time we chose 40 samples per second. For the non audio system test I used a KAL carbon pile load tester. It can do power tests on 12 volt charging systems up to 1200amps continuous. The audio system consisted of a couple of Rockford 1100 amps bridged into four ohm nominal speakers. The alternator was a stock Delco 80 amp CS type unit. Its case temperature was monitored by a Raytek ST2L IR sensor. Engine speed was regulated with a Thexton #398 IACV tester. The music material was the SPL track # 30 from the IASCA competition disc. The battery was a Stinger spb-1000. All voltage measurements were done directly at the terminals of one of the amps.</p><p></p><p>Chart 1 Alternator/cap/batt test with 200 amp dummy load</p><p></p><p>For this test we monitored the voltage of the car with the stereo turned off. With the car running the voltage can be seen to be stable at about 13.7 volts. After 22 seconds (The horizontal scale is 100 seconds-10 sec per major division) we applied a 200 amp load. The voltage can be seen to drop to 11.6 on both traces. This test obviously exceeds the ability of the alternator to keep its regulation set point so its voltage falls. The drop can be seen to be nearly instant (steep curve) until about 12.5 volts where the battery starts to supply a significant amount of the power. Ultimately the voltage drops to 11.6 and at 26 seconds we turn off the load. The voltage then starts to rise to the regulator set point as the battery is recharged (yellow curve) and as the battery and cap (green curve) are recharged. At a time of 50 seconds I turn the motor off so the alternator stops. The voltage then droops down to the float voltage of the battery—about 12.7. The only reason for the small difference at 50 seconds is because I couldn’t get the timing of the engine shut-off exactly the same every time. I did it several times and these two are within one second. That was as close as I could get it.</p><p></p><p>I am able to see no difference from these measurements. There are microscopic differences but I believe they are due to the alternator temperature. Alternator regulators are usually temperature sensitive. As they get hotter they tend to fold back. For this reason we let the unit cool off between each test and closely monitored the case temp throughout the tests. For this reason I believe that none of these measurements are meaningful to more than a couple tenths of a volt.</p><p></p><p>this came out of a post on carsound about the uselessness of big cap cause of the ESR. It thread is 5 pages long. For some reason poeple seem to think that RC is tring to show ALL cap don't work........ he isn't ---- he is just showing BIG caps don't because of the ESR</p><p></p><p>here is the thread</p><p></p><p><a href="http://www.carsound.com/ubb/Archives/Archive-000001/HTML/20010126-1-000307.html" target="_blank">http://www.carsound.com/ubb/Archives/Archive-000001/HTML/20010126-1-000307.html</a></p><p></p><p>----------------------------------------------------------- but the battle continues against the uninformed</p></blockquote><p></p>
[QUOTE="chris229, post: 83139, member: 542614"] guys----------- looks like BIGBASSMAN has use a graph show the uselessnes of big ESR caps and the 200A load is to show that the high ESR kills the design RC text------ Lesson 8 For this lesson I have done some actual measurements. Here are the test conditions: To measure voltage we used an Audio Precision with a DCX module. It is accurate to three decimal places. For sample time we chose 40 samples per second. For the non audio system test I used a KAL carbon pile load tester. It can do power tests on 12 volt charging systems up to 1200amps continuous. The audio system consisted of a couple of Rockford 1100 amps bridged into four ohm nominal speakers. The alternator was a stock Delco 80 amp CS type unit. Its case temperature was monitored by a Raytek ST2L IR sensor. Engine speed was regulated with a Thexton #398 IACV tester. The music material was the SPL track # 30 from the IASCA competition disc. The battery was a Stinger spb-1000. All voltage measurements were done directly at the terminals of one of the amps. Chart 1 Alternator/cap/batt test with 200 amp dummy load For this test we monitored the voltage of the car with the stereo turned off. With the car running the voltage can be seen to be stable at about 13.7 volts. After 22 seconds (The horizontal scale is 100 seconds-10 sec per major division) we applied a 200 amp load. The voltage can be seen to drop to 11.6 on both traces. This test obviously exceeds the ability of the alternator to keep its regulation set point so its voltage falls. The drop can be seen to be nearly instant (steep curve) until about 12.5 volts where the battery starts to supply a significant amount of the power. Ultimately the voltage drops to 11.6 and at 26 seconds we turn off the load. The voltage then starts to rise to the regulator set point as the battery is recharged (yellow curve) and as the battery and cap (green curve) are recharged. At a time of 50 seconds I turn the motor off so the alternator stops. The voltage then droops down to the float voltage of the battery—about 12.7. The only reason for the small difference at 50 seconds is because I couldn’t get the timing of the engine shut-off exactly the same every time. I did it several times and these two are within one second. That was as close as I could get it. I am able to see no difference from these measurements. There are microscopic differences but I believe they are due to the alternator temperature. Alternator regulators are usually temperature sensitive. As they get hotter they tend to fold back. For this reason we let the unit cool off between each test and closely monitored the case temp throughout the tests. For this reason I believe that none of these measurements are meaningful to more than a couple tenths of a volt. this came out of a post on carsound about the uselessness of big cap cause of the ESR. It thread is 5 pages long. For some reason poeple seem to think that RC is tring to show ALL cap don't work........ he isn't ---- he is just showing BIG caps don't because of the ESR here is the thread [URL="http://www.carsound.com/ubb/Archives/Archive-000001/HTML/20010126-1-000307.html"]http://www.carsound.com/ubb/Archives/Archive-000001/HTML/20010126-1-000307.html[/URL] ----------------------------------------------------------- but the battle continues against the uninformed [/QUOTE]
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