Test/Review of Xtar VI01 USB Current/voltage detector

Wurkkos

HKJ

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[size=+3]Xtar VI01 USB Current/voltage detector[/size]

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Xtar has made many flashlights and good chargers, this is a new type of product from them. It is a current and voltage meter to use in a usb connection.

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I got the device in a cardboard/plastic package. It was very easy to open, the cardboard could slide out. The only contents in the package is the device, no usb cable or instruction sheet and it is not needed.

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There is an usb connector in each end, one male, one female.

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One of the usb connections has a loose cover. I like having a cover over the usb connector, but I do not like loose parts.

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Here it is plugged into a laptop and connected to my phone. The display will show 3 digits and a letter, A for ampere and U for volt. The decimal place is always fixed giving the display a resolution of 0.01 volt and 0.01 ampere.

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Another test with my laptop, this time with two different cables.
When using the two wire cable the phone will only charge with low current. Using the 4 wire cable (with data), the phone can charge at much higher current.

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Some other tests it can be used for.



[size=+2]Measurements[/size]

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To measure I needed some connection with very low resistance. I made two usb connecter with fairly thick wires sticking out.

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First I measured the two when connected together, the result was 0.03 ohm or 30mOhm, for the wires and connection between the two.
Because I do not know how this is distributed, I cannot compensate for it in the voltage measurements. Anyway, these looses will also be present when using it in real situations and usual they will be larger.

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With the device connected.

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The actual setup required two high precision DMM's, one to measure input voltage and one to measure output voltage and a electronic load.
Voltage was measured on the wires sticking out of my test usb connectors, to avoid voltage drops in thin usb wires.

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About are some of my measurements. In the two red lines I am way outside the rated specifications and the display shows wrong values.

With a few more test I could draw some conclusions:
  • Volt was within +/- 0.01 on the display when not loaded.
  • Ampere is within +/- 0.02 on the display.
  • When loaded with 2.5A the displayed voltage is about 0.1 volt to low.
  • When loaded the voltage will drop, calculations shows the device has between 0.16 and 0.17 ohm resistance, this includes the measurement resistor, the internal connections and connections resistance (The 0.03 ohm from above is subtracted).
  • The voltage is shown for the input voltage, i.e. the voltage on the usb output that supplies the current to the device.
  • When voltage drops below 4 volt the precision will be reduced (The device is only supposed to work down to 4.5 volt).
  • The voltage readout is usable down to about 3 volt.
  • The device uses 0.025A (25mA) from the usb power, this current is not included in the display reading
  • The usb data lines are passed through, this means the coding on a usb output will be seen on the connected device.


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After a short time the measurement resistor in the device gets warm.

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Running 1 hour at 2.5A made it warmer (max. temperature is higher, see scale) and the current readout was still correct.



[size=+2]Conclusion[/size]

The device works as expected and can be very useful to check all types of usb devices with.
The voltage readout will be precise at small loads (i.e. below 1A), but at the higher current it will show a slightly low a value. The current readout is always precise.



[size=+2]Notes[/size]

The device was supplied by Xtar a review.
 

ven

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Thank you HKJ for your excellent review..........i like it,looks very useful and will more than likely invest in one of these.

Thanks again:thumbsup:
 

HKJ

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i like it,looks very useful and will more than likely invest in one of these.

If you have a pile of usb chargers and power boxes, together with a lot of usb equipment it is very useful. It is
easy to do a quick check if stuff is working as expected or you are overloading a usb power output.
I do not have any usb heaters, coolers, fans, etc. or I would have included a picture measuring current of that kind of stuff.
 

psychbeat

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SF norcal
I have a solar panel with a USB out from Cottonpickers & one of these would be convenient to quickly put in line & then remove so as not to take up any power.

Thanks for the review !
 

digiowl

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Dec 30, 2013
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Should be a nice tool for finding all those non-spec USB chargers. I really wonder how hard it is for OEMs to short those data pins...
 

bhonder

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Would you like to test if it works too with data devices like pen drive, dvb tuners, GPS and soon on.
It would be interesting.
 

HKJ

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Would you like to test if it works too with data devices like pen drive, dvb tuners, GPS and soon on.
It would be interesting.

I am not going to test all these devices, but it works fine between a computer and memory stick, i.e. it will probably work with just about anything.
 

tobrien

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i've had one of these and HKJ's review was insightful, thanks man! i love mine.

so i don't need to worry about the VI01 altering how the phone sees the charger or how the charger sees the phone? I know some phones have a special data whatever setting that allows them to charge above the USB spec, right?
 

bwDraco

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New York
A bit of a late post, but I got two of these USB detectors from XTAR Direct and am happy to report that sample variation between the two units is minimal, differing by no more than 0.01V and 0.01A. However, it seems to insert some non-trivial resistance to the USB power lines, which can slow charging of certain devices. I did not find the USB connector cap to be loose. As expected, accuracy is excellent and matches up with your lab tests.

(A side note: I have a second-gen Anker Astro3 12000 mAh USB battery and was able to determine that the overload protection cuts out at about 5 A on a Universal port, with a response time of about 0.3 seconds, allowing for momentary peak loads exceeding the rating. The battery itself is specified for a maximum load of 4 A. Of course, you do not want to subject the detector to currents exceeding the rating for any extended period of time as it will overheat and fail!)

--DragonLord
 
Last edited:

HKJ

Flashaholic
Joined
Mar 26, 2008
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Location
Copenhagen, Denmark
A bit of a late post, but I got two of these USB detectors from XTAR Direct and am happy to report that sample variation between the two units is minimal, differing by no more than 0.01V and 0.01A. However, it seems to insert some non-trivial resistance to the USB power lines, which can slow charging of certain devices. I did not find the USB connector cap to be loose. As expected, accuracy is excellent and matches up with your lab tests.

For the voltage drop: Look in the table, the 2A and 3A entry does reveal how much voltage drop the device has (See Vout column).
I do have a couple of other similar usb voltmeters in queue, in varying precision and with different voltage drop.
 

mactavish

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Jun 23, 2013
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Thanks for the review. Got one of these bundled with the new Xtar MC1 Plus charger. Tested inline with the PortaPow you also reviewed. Now testing with iPhone 2.1A charger. Nice to have.
 

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