WARNING – Nerd Post

Be advised this is a nerd post.   Unless you are interested in nerd things you might want to stop reading now.

This morning the postman delivered the USB Tester I’d ordered from China.

The tester came nicely presented in a foam padded tin box with a card on which a QR Code had been printed.  The code needed to be scanned to download the user manual.  A clever way of cutting costs.

What does the tester do?  From the manual…….

The FNRSI FNB48 USB tester is a high-reliability, high-safety USB voltage and
current detection meter and a mobile communication terminal fast charging
trigger. It has a 1.77-inch TFTLCD display and integrated USB-A, Micro-USB,
Type-C interfaces. Use external 16-bit ADC, PD protocol physical chip. It
can be used to measure the power supply or power consumption of products
such as USB interfaces, mobile phone chargers, U disks, etc.; it can be used
to measure mobile phone charging power and mobile power input and output
conditions; it can be used for charger fast charging protocol testing.

The Tester has a number of input and output ports

• USB-C Input
• USB-C Output
• Micro-usb Input

• Micro-usb port to Computer (for firmware upgrades, etc)
• Control knobs

All marked out on the back

! want to initially use it to identify several things

• What is the current battery capacity of our various mobile devices (phones, tablets, etc)
• Which of our chargers produce the most power
• Which of our usb cables has the least resistance and is the best of charging.

When charging devices we use various sources which include:

• usb port on the laptop
• powered usb hub
• 240V power bricks

I already knew the laptop port had the lowest power output.  But how low?  We also have a variety of usb cables.  Which would be the best?

The Tester even has an oscilloscope screen! 

Jan’s Samsung Galaxy S4 was used for the tests

Without boring you further I can advise the different combination of power sources and cables resulted in a wide variation in charging power.  The worst combination resulted in the phone receiving 1.29 Watts and the best 3.07 Watts. The best was more than double the worst.

I’m now using it to establish the true battery capacity of the old Samsung Tablet.  At this time I haven’t scratched the surface of the Testers capabilities.