Drok USB Load Tester?

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Pete7874
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Drok USB Load Tester?

Is this thing any good? Anyone has one or one just like it under a different brand name? I’m sure you can get it for less from China directly.

USB Load Tester, DROK DC 3-21V Load Battery Tester, 35W 3A

BlueSwordM
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Yes, but this thing is better, cheaper, and can trigger quick charging protocols:

https://www.aliexpress.com/item/RD-HD25-HD35-Trigger-QC2-0-QC3-0-Electro...

I personally have it, and tested. Works extremely well for its purpose, and works for triggering QC 3.0/QC 2.0. It also has a nice display for current and power, although not to the same level of the meter you showed, but it also has USB-C input and micro-USB input for testing with a cable.

Pete7874
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Drok says it’s compatible with QC2.0/QC3.0, but I’m not sure if that means it can trigger them or not.

BlueSwordM
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Compatible means it can passthrough QC 3.0, but not trigger it.

That means it only works with a QC 3.0 capable device (charger/phone) Sad

No constant current load for us.

rizky_p
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BlueSwordM wrote:
Yes, but this thing is better, cheaper, and can trigger quick charging protocols:

https://www.aliexpress.com/item/RD-HD25-HD35-Trigger-QC2-0-QC3-0-Electro...

i have the same tester and it is working nicely and can trigger QC 3.0 or QC 2.0, but i have to paired it with another tester to get better reading since the HD35 only provide basic and hard to read text.

Pete7874
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So, can this device be used to test quality of USB cables, meaning current loss? How does it need to be hooked up for this?

BlueSwordM
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Yes, and it is very easy. I personally do a manual calculation so it is more accurate because the contact resistance of the USB port insertion can easily change, but here’s the official method via the firmware of the UM25C:

1. Plug in the USB tester in the USB power supply of your choice with the load attached, and press the NEXT button until you get to the menu like showed on the pic.

2. Set the load at 1A for measurement consistency, and power it on. You’ll see the green lines displaying the voltage and current values.

Press the NEXT button, and keep holding it until the green values are recorded and the yellow part starts flashing. Disconnect the USB meter from the supply.

3. Instead of plugging in directly the meter, put in the USB cable you want to test in any of the IN ports, be it USB-C or micro-USB.

You’ll boot up back in the cable testing menu. And you’ll see the yellow lines displaying the current and voltage values.

Press the NEXT button, and keep holding it until the yellow values are recorded, and voilà! The meter will calculate the cable’s resistance, and you’ll be able to see if you have good cables or not.

For reference, excellent cables will have a resistance below 0,120 Ohms, good cables will be between 0,150-0,120Ohms, and bad cables will have a resistance over 0,200Ohms.

Note: The cable tested in the picture only has been used for reference. The measured resistance is not accurate because of my unstable testing ground.

Pete7874
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Thanks. I was actually asking how to do this using the DROK tester I linked in the OP. Sorry for not being clear.

The supplied owner’s manual is fairly useless.

Can I manually calculate the cable’s resistance based on the the observed voltage drop?

BlueSwordM
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Yes. Manually calculating the resistance of the cable is also more accurate than having confidence in a good USB plug.

1. Plug in the USB cable into the load tester/monitor.

2. Note the average idle voltage, say 5,00V.

3. Set the current to 1A.

4. Take the measured voltage under load, say 4,90V and do this:

∆V = Vidle – Vload
I = Current under load = 1,00A
Vidle = 5,00V
Vload = 4,90V
R = Resistance of the cable in Ohms = V/I

∆V = 5,00V – 4,90V = 0,10V

R = V/I = 0,10V/1,00A = 0,100 Ohms

Easy as pie.

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Thank you.

By the way, I like that combination of UM25C and HD35 – seems like this combo is more versatile than this Drok all-in-one unit. Is Aliexpress the best place to buy these? I’m seeing the combo for $31 right now.

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Yes, especially if you ask for a small price reduction from RD Tech if you mention that you are a BLF member before making the order, and are making the order in the app:

https://www.aliexpress.com/item/RD-UM25-UM25C-for-APP-USB-2-0-Type-C-LCD...

rizky_p
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i always wondering what is that screen is for, thanks for showing how to do it.