Plugable USBC-VAMETER Gen 2

Plugable USBC-VAMETER Gen 2 – for nerds who need to know (review)


The Plugable USBC-VAMETER Gen 2 is an inline VA (Volt/Amp) meter that measures the actual charge speed and power use of a connected USB device (external storage, smartphones, and laptops to 100W).

Now Mr Ohm has a lot to say about his law – Volts x Amps = Watts. The Plugable USBC-VAMETER Gen 2 helps solve charging issues and identify why things may not charge as fast as they should.

First, a little voltage primer

Have you ever noticed that USB-A and USB-C chargers are rated by Watts? That is because Watts don’t change. Volts and Amps do, but they must multiply to a constant Wattage. So, a 5V/3A/15W is the same output power as a 9V/1.67A/15W etc. USB-C PD also offers a range of amperages but watts are constant.

If you are good at maths, you can convert a battery’s mAh to Wh (how many Watts it can deliver for one hour) and work out how long it takes to fill. For example, a typical smartphone battery has is 4.3V (it is never 5V; there is an efficiency loss in charging from USB) and 4,000mA (milliamps and 1000 = 1A). So, the battery needs 4.3V x 4A = 17.2W to charge. A 15W charger should fill it in about 1.5 hours.

A USB-C PD fast charger can negotiate different wattages and may start at 20V/1.25A/25W for the first 20%, then 10V/2A/20W for the next 60% and 5V/2A/10W for the last 20%. The higher the wattage, the more it generates heat and stress; hence it drops back.

Review: Plugable USBC-VAMETER Voltage and Amperage meter (Gen 2 for 2021)

This portable USB-C passthrough meter allows users to quickly and easily see how fast a USB-C device is charging or drops under load so that they can find and fix any power issues. It has an updated design and new features, such as:

  • A new button to rotate the screen orientation and make switching between orientations easier than ever
  • A brighter and easter-to-read screen
  • An overall more robust design with strengthened USB-C connectors
  • USB Power Delivery voltage to 100W – from 5 to 20V/5A and PD 4-20V, 50mA-10A operating range
  • Uses VBYS lines – data lines are untouched
  • Works with USB-C 3.2 Gen 2 (10Gbps) and USB-A 30.0 and earlier via adaptors
  • Transient Voltage Suppression (prevent inrush current spikes)
  • 2-year warranty
  • Not compatible with Thunderbolt 3 or 4 ports unless in USB-C mode
  • Website here (images and may be updated after launch)
  • From: Amazon AU or Plugable
  • Price: <A$30

Why buy a Plugable USBC-VAMETER Gen 2

It is a niche product – a relatively low-cost tool for measuring voltage and amperage of any USB-A or USB-C device (to 100W) while it is charging. It also indicates the current drain of a screen on-or-off device.

I lined up several smartphones and USB-C chargeable notebooks and the results were interesting – very interesting.

We use the Android Simple Battery Graph (here) to measure charge and discharge times and get a graph of the different charge speeds and Android Battery Monitor Ampere (here) to measure battery life in our smartphone reviews. We also use an expensive Power-Z hardware monitor (here), and you will often note that we find issues and more accurate battery life that other reviewers miss entirely. Most of the time our recharge test results are very different to the PR/Marketing Hype and the Plugable USBC-VAMETER tells us why.

Bear with me. If you have a standard 5V/1 or 2A USB-A charger that means it should charge in a linear manner from start to finish. If it has USB-C PD (let’s say 25W) it may start a 20V/1A for the first 30%, 9V/2A for the next 30% and 5V/3A to get to 80%. Then depending on battery heat and PD telemetry it may drop to 5V/2 or even 1AS to top up the last 20%. Or look at OPPO’s amazing SUper VOOC 2.0 that is a 56W charge that can fill a battery in under 35 minutes.

Except that we have discovered quite a few supposedly USB-C PD phones do not really support PD. The meter tells us exactly the voltage and amperage at any one time. I only wish it had video-out to produce a graph over time. That is where the much more expensive Power-Z metre comes in.

So its a tool to explain why something is taking so long or so short to charge, and yes, every nerd should have one.

You can read other GadgetGuy Plugable news and review here.

Plugable USBC-VAMETER Gen 2
So its a tool to explain why something is taking so long or so short to charge, and yes, every nerd should have one.
Value for money
Ease of use
In-line USB charging volt/amp/charing meter
Low cost - ideal for nerds tool boxes
Helps troubleshoot slow charging issues
None really - its plug and play