KJ-KayJI

"Is this USB charger working?"

"Is this USB port broken?"

"Is this device charging properly?"

Also: ThisUSB charger can power four devices at once and look good doing it

"Is this gadget charging?"

"Is the battery in this gadget accepting a charge?"

I'm amazed at how often I'm asking one of the above questions when I'm examining a broken, malfunctioning, or otherwise misbehaving device.

USB ports are everywhere, and it's no coincidence that USB port problems are an increasingly common issue that those who diagnose or repair gadgets havetoface. And without the right tools, you can be left tearing your hair out trying to figure out what's wrong.

Also: You're using super glue all wrong

I have a bunch of tools that I can plug into USB ports, ranging froma few dollars to over$100 , but if you're starting out, here'sa kit that has everything you need to troubleshoot USB-A, microUSB, and USB-C ports for under$25. 

KJ-KayJI 2 in 1 USB Tester

$23.99 at Amazon

KJ-KayJI 2 in 1 USB Tester tech specs

• Ports supported: USB-A, USb-C, and microUSB.
• Maximum voltage and current: 32V/5.1A/150W.
• Charge protocols supported: PD3.0/PD2.0, QC3.0/QC2.0, BC1.2.
• Display: IPS LCD multi-color screen.
• Safety: Over-voltage protection.
• Measures: Voltage, Amperage, temperature, mAh, resistance, and more.

This kit comes with everything you need to test USB ports. You get the tester, a USB-A to microUSB converter, and an adjustable 1A/2/3A load.

Also: The best USB hubs   

The tester is a low-cost tool that allows you to test the output of chargers and power banks. It's also a way to check the rated capacity of a device or the condition of the battery.

The adjustable load gives you a "fake" device to plug into a power bank or charger to act as a load, so you can see if the device is working properly. One note of warning here is that these adjustable loads get hot when used -- really, really hot -- and it's advisable to get aheat-resistant surface to put them down on when in use.  

The tester comes with an instruction manual, and while it's better than nothing, nothing beats experience. The best way to learn how to use this device is to experiment.

 Also: This $11 gadget is a must-have for aging eyes

One feature that makes theKJ-KayJI 2 in 1 USB tester easier to use than many is that there's only one button to press -- a short press moves you between the different screens on the display, while a long press resets all the readings to zero.

Plug the tester between a smartphone or laptop and a charger, or a power bank and a load, and see what results you get. The more you use this tool, the more you'll understand what a charger or power bank should output (you can usually find this information printed on the charger or power bank) -- and the better you'll be at spotting when something isn't right. 

Also: The perfect$16 USB tester for your repair kit (and how to use it)

This is a great USB tester that's ideal for those starting out on their diagnostics and repair journey, as well as experienced users who want a spare tester. I have a couple of these testers and I find them to be just as good and just as accurate as testers costing two or three times the price.

See also

This$30 gadget claims to add years to your phone's lifespan. Here's howThis is the USB flash drive James Bond would useHow to strip wires like a pro (and my must-have tools)Stop! Your Apple charger may be a counterfeit, and this tiny gadget can tellThis$10 gadget is my favorite repair tool of all time

• This$30 gadget claims to add years to your phone's lifespan. Here's how
• This is the USB flash drive James Bond would use
• How to strip wires like a pro (and my must-have tools)
• Stop! Your Apple charger may be a counterfeit, and this tiny gadget can tell
• This$10 gadget is my favorite repair tool of all time