USB 1.x and 2.x - all data speeds. Does not have USB v3 pins so USB v3 connections will automatically downgrade to v2
Working Range: 0~3A, 3.5~7VDC
Resolution: 10mV / 10mA
Operating Temperature: 0-60ºC
This meter exist in a couple of different versions with minor differences (SMD vs. leaded parts).
How does it look
One of the digits is used to show U or A, depending on what is shown on the display.
The difference between the version is the leaded components, they have been replaced with smd components.
Not very nice looking, the circuit board has not been cleaned after soldering. The measuring resistor can be seen here, it is marked R050, i.e. 0.05 ohm (50mOhm).
Measurements
Voltage is within 0.03V when unloaded (Tested from 3.5 to 6 volt).
Current is within 0.06A.
When loaded the voltage is somewhere between input and output voltage.
The meter uses 22.3mA current
Works down to 3.27 volt
Internal resistance is about 0.14ohm including connection resistance.
USB data works fine.
M1: 57,5°C, HS1: 66,9°C
Notice that the hot spot is in the connector, it has a rather high connection resistance and is getting hot.
Conclusion
The internal resistance is acceptable and the same with the precision.
With two digit resolution for both voltage and current it is a good usb meter.
It looks like there is a new generation of these on the market where the resistor is changed from R050 to R100, i.e. the resistance is 0.05 ohm higher.
I don’t get the part about amps, I wanted to see if a plug in for the lighter produced 2 amps, do I need to put this in between the adapter and what I’m charging to see the amps?
Also, is there much difference from an adapter that will produce 2.0 amps, and the 2.1 amps that apple products call for, or is that pretty much meaningless?
Yes, you have to plug it in between the adapter and whatever you are charging. Then it will show how much current you are charging with, not how much your adapter is capable of. Because these usb meters add some resistance, some devices may reduce their charge current.
If there is a difference between 2.0 and 2.1A depends on the adapter and the device you are charging. A smart adapter may reduce the output voltage when to high current is draw and a smart device may get the hint and reduce the charge current.
Henrik: Could you give us your preference between these (Charge Doctor) and the XTAR USB unit please. Any pros or cons between the two. Is one better than the other? I would really appreciate and respect your comments.
One very important parameter is the internal resistance, it must be as low as possible (Charge doctor wins there), but the Xtar has better precision and works at a lower voltage.
I prefer another one, but that review is not published yet
The question is hos long you want to wait. I have done a couple of reviews more and know one of them is better, but I have more usb meters in queue for reviews and do not know how they perform. I will probably also be publishing other reviews, i.e. it might be close to xmas before I am finished with all the usb meters or maybe even next year, depending on how much other stuff I review.
With the speed I publish (One review each other day), I have to plan and write ahead. I.e. do the testing and write the reviews when I have time.
I just received 2 more of these from BIC at only $1.79 each. From the pics on the site I expected a knock off but they appear to be the same. So I ordered 5 more.
Gift time!
EDIT: I just checked more closely and the more recent one I recieved from BIC differs from the first one. Here are the pics
The original one I received is on the bottom, scratched up, the most recent on top. They look the same.
but from the back, there are differences. My original one looks more like what is in this review.
The one I received a couple of days ago on top and my original on the bottom.
Thanks for the review HKJ. I bought one of these some time ago (I think on Chloe’s recommendation) and find it quite useful. A silly question, but is is easy to remove the blue plastic cover without damaging it? Can it be replaced again once removed?