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CT-3 Cable Resistance Test Normal A - C results N/A

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发表于: 11-09-2022 11:35:35
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Edited by StatiC at 11-09-2022 11:49

I just got the CT-3 (aluminum case) meter today (ordered through Amazon) and really love this thing so far with all of it's features and really nice display menus.  Really great job with this device.  The only problem that I am having so far is with the cable resistance test.  Testing the A - C cable, I just get N/A for ESR.

These are the steps I am following per the online manual...

1. Plug meter into power bank with the A male port.
2. Plug load into A female port (1 amp USB A LED light strip)
3. Go into menu and select 'Cable Resistance Test'
4. Go into menu and select 'Normal (A-C Only)'
5. Click button to confirm 'I've plugged'
Outputs:
Vref: varies 5.02A to 5.035V
Iref: varies 1.05A to 1.07A
6. Unplug from USB power bank
7. Plug A -> C cable between meter and power bank
8. Click button to confirm 'I've plugged'
Output results...

Vref: 5.036V
Iref: 1.058A
Vcrt: 4.882V
Icrt: fluctuates between 1.004A and 0.989A
ESR=N/A


I have repeated this about a dozen times and it always shows ESR=N/A.  Am I missing something?  One of the main reasons to purchase was to test cables so I am hoping I am just missing something.

EDIT: I tried a second cable with the same result (slightly different values output of course but end result is ESR=N/A).  The Bypass(C-C Only) test seems to work fine with C - C cable that I just tested.  Seems to be only the A - C test that isn't working.

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发表于: 11-09-2022 15:12:53
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Hi
Thank you very much for your feedback, we are analyzing your issue.
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 楼主| 发表于: 11-09-2022 16:53:34
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Thanks for the response.  It is good to know support is active.

I noticed a Q and A post on this forum stating that the current needs to stay within 10mA in order for the test to return a result instead of N/A.  I did see it varying a lot before I changed the display update frequency to 'slow'.
https://forum.avhzy.com/forum.php?mod=viewthread&tid=23

The tests I did below were all less than 10 mA but still resulted in N/A.  Maybe the current is varying a lot though so its quick ups and downs make it more than 10 mA that the average doesn't show.  I suspect that is true.
Cable        Vref        Iref        Vcrt        Icrt        ESR
Cable1        5.153        1.215        4.997        1.134        N/A
Cable2        5.153        1.215        4.986        1.144        N/A

I ordered a constant current load tester to plug in for the load instead of relying on a cheap LED light strip I bought awhile ago.  I should get the new load tester in a couple days and I will do the tests with that and see if it can keep a constant current for the cable tests.

https://www.amazon.com/gp/produc ... _asin_title_o00_s00
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 楼主| 发表于: 11-09-2022 20:01:01
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Edited by StatiC at 11-09-2022 21:32

I found that using my 30% charged iPad Pro (2019 model I think) as a load with an iPhone 1 amp charger keeps the current constant around 0.995 mAh regardless of the A - C cable that I use.  I got a result from it.  So the problem does appear to be that the current is changing too much to return a valid result with the USB LED light strip I was using.

It seems to be working fine with this setup.  It will be interesting to see the current variability with the load tester I ordered.  I know I have a solution though with the iPad and iPhone charger.
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发表于: 12-09-2022 18:31:39
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Hallo Kunde
Leichtes hochfrequentes Rauschen ist im Leerlauf normal.
Im Gehäuse befindet sich ein Widerstand, der verbessert werden kann, indem er an den positiven und negativen Pol des AC-DC-Moduls angeschlossen wird.
Wenn Sie den Lärm immer noch nicht ertragen können.
Bitte antworten Sie mit Ihren Lieferdetails.
Wir senden Ihnen ein nicht verkaufbares Produkt aus dem Amazon-Lager als Zubehör zum Austausch des AC-DC-Moduls im Inneren zu.
Es tut mir sehr leid für die Ihnen entstandenen Unannehmlichkeiten.
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 楼主| 发表于: 13-09-2022 10:10:03
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The problem definitely was that the LED light strip I was using was changing current.  The new load tester I bought works great at keeping the current steady regardless of the USB A-C cable that I use.
Thanks for the help (email support was great too).
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 楼主| 发表于: 18-09-2022 13:15:26
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As a followup, The cheap 15W USB Load Tester (0.15A to 3.0A) that I bought also works great to keep current constant for the wire testing.  Thanks again for the help.
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