Ok, I have reviewed a few RD tech products in the past and have been happy and very impressed with all of them.
About a year ago I reviewed the old USB tester and load tester that they offered and they worked quite well at testing USB power ports and to see if USB devices were working or charging like they should.
I have used it far more then I would of guessed since I got it.
They recently released a new version of both the USB tester and Load tester. When they first approached me about reviewing it I was skeptical as I was not sure what you could really improve.
The big selling point seemed to be a Bluetooth app to watch the meter on your phone, which I saw as more of a niche use case.
The I saw the real improvement, the new versions had Micro-USB and USC Type-C input ports!
At first that does not sound like much but this now allows you to test your USB cables to make sure they are not the problem. In addition to being able to use the tester with a cable plugged in instead of being tied to a USB port at odd angles.
I actually had the perfect item I wanted to test this on so I told them to send me a sample for review. Took me longer then I want to admit to get around to it but I finally did.
So I have had 2 of the LII-402 chargers for some time but they would only ever charge 3 cells at a time. I had always thought that the cables could be the problem but when I tried what I thought were better cables it did not fix the problem.
Now I can find out for sure!
At first glance both the USB tester and Load tester are larger then the older versions but also a lot more features. The load tester by itself also now shows voltage for example.
And the USB tester has a much larger and earier to read screen:
So first I set about playing with the features and basic testing, such as the mah counter that shows how much power your device has used:
The voltage graph:
and menu (I recommend upping the screen timeout):
So now to start testing, First I plugged in the charger with some drained cells to the tester and decided to see what happens.
It would gladly pull 1A but anytime I tried to start more then 2 cells charging it would stop them and just would not go above 1A.
So now to test the Cable, I unplugged the charger and plugged the cable into the load tester to get an idea of what was going on, at 1A it was only getting 4.6V to the load tester:
At 2A it was at 4V (now it was lower then normal since there were 2 cables but the outcome is the same)
Thus this seemed to confirm my idea that the cable was the issue. So I tried my known good cable with the charger and sure enough, it worked perfectly!
Then I got down to the technical testing. I connected the tester directly to the USB power adapter and took a baseline voltage reading by holding the next button on the following screen with 1A of current being pulled through it. This records the input voltage from the power adapter at this current.
After that I disconnected the tester and then plugged in the cable in question to the same power adapter (so the input voltage would be the same) and to the tester input and turned the 1A load back on. I then held the next button again so it can run the calculation and here is the result:
No wounder it was shutting down with more then 3 cells charging, it was only seeing at most 4.1V! The stock cable with the LII-402 has a whopping 762mohm’s of resistance.
To put them in perspective my good cables had around ~150-200ohms with most in the 300-500ohm range.
I then set about testing all the other cables I had, finding that you really can not judge a book by it’s cover. Some I was sure would suck were not bad and some I thought were good were bad.
I ended up just connecting the cables to a 1A load and seeing what the voltage was, anything over 4.5v passed as usable. Anything over 4.75v was good. I had 2 that were over 4.9v that are very good.
Overall well worth the time and money IMHO to finally be able to scientifically sort all my cables and figure out which ones to keep and which to toss aside.
I did not try the Android app myself as I don’t install random apps unless I can’t help it but I looked it up and it looks nice. Good for watching things from afar.
RD Techs official store is located here: https://rdtech.aliexpress.com/store/923042
I also use 2 of their power supplies almost daily as well. Only issue I have had is I used one of them so much I wore through the plastic cover on the power button lol.