The Practical Meter by Power Practical (makers of the PowerPot) allows you to measure the power output of your USB charging device to ensure that you’re getting the most out of it!
Compatible with any USB charger
Measurement Range: 1 to 5 Watts
Resolution: 1 Watt (rounds up)
Physical Size: 1.7” x 0.9”
The Practical Meter by Power Practical is an inline USB power meter that measures the output of your USB charging devices to ensure that you’re getting the most out of them. This low-profile, lightweight power meter is compatible with any standard USB charging port and provides real-time feedback via an easy-to-read, “five bar” display. Each bar on the display represents one Watt of power and the meter rounds up to the nearest watt (i.e. 2.5W will appear as 3W on the display). Simply plug it in between your charger and USB device and watch it work! It’s a great companion for tech-savy outdoor enthusiasts because it helps to take the guesswork out of recharging USB-powered devices in the field. It can be used for everything from aligning solar panels for optimum power output to monitoring the performance of thermoelectric devices to help save on fuel.
I recently had the opportunity to try out a prototype Practical Meter and I was impressed with its utility and performance. It not only worked well with all of my USB-powered devices but it also gave me some new insights into their charging capabilities. For example, I had always wondered why it took so long for my smartphone (HTC Droid Incredible 2) to charge when using 5W-USB sources. It turns out that my phone is only capable of charging at a maximum of 0.5A (2.5W from a standard, 5V-USB port)! Granted, I may have learned this had I taken the time to read the user’s manual that came with my smartphone but who has time for that?? Anyway, this discovery inspired the following investigation into the performance of some of the industry leading portable power devices including the Power Pot V, Biolite Campstove, and the Goal Zero Nomad 7 solar panel…
My first experiment aimed to compare the performance of two thermo-electric generators: the Power Pot V and the Biolite Campstove. The tests involved measuring the power output of these devices via the Practical Meter for duration of 20 minutes from start-up as they charged my HTC Droid Incredible 2 smartphone (2.5W max recharge rate). The graph below displays the results with the red line representing the Power Pot V and the blue line representing the Biolite Campstove. The Power Pot took about 2 minutes to get up to the maximum recharge rate of 2.5W and was able to sustain this for the duration of the test. This was especially impressive considering that the Power Pot was half-filled with room temperature water at the start of the test and it was able to achieve the maximum recharge rate well before the water boiled (which occurred at about 5 minutes into the test)!
The performance of the Biolite Campstove was equally interesting. The test confirmed my suspicion that the power output of the Campstove is highly dependent on the intensity of the fire. This may seem obvious to some readers but it can be hard to tell when to stoke the fire in order to maintain power. For example, the fire may not appear to be weakening so much yet the power output has already started to drop off. The Practical Meter solves this issue and allows you to stoke the fire at the first sign of decreased power.
As the graph shows, the Campstove was stoked with additional fuel on multiple occasions in order to maintain the maximum recharge rate of 2.5W. The Campstove was able to bounce back fairly quickly (within 1 minute) in most instances when fuel was added. However, one can appreciate that this unit requires more attention to maximize its power output and that these fluctuations in output will serve to decrease the average power supplied and thus increase the time that is takes to charge your small electronics in the field. Furthermore, the CampStove was already operating at full capacity at the start of the test whereas the PowerPot started off “cold” with water at ambient temperature.
The Practical Meter is also a useful tool for monitoring the power output of portable solar panels. This was the subject of a second experiment to evaluate the performance of the Goal Zero Nomad 7 solar panel at high noon on a partly cloudy (and otherwise beautiful) day! This test involved measuring the power output of the solar panel via the Practical Meter for duration of 20 minutes from start-up as it charged a Goal Zero Guide 10 Plus battery pack (5W max recharge rate). The graph below displays the results with the blue line representing the Power Pot V (control) and the green line representing the Nomad 7 Solar panel.
The Power Pot was able to produce 5W of power within 1 minute of start-up and maintained this maximum rate for the duration of the test with minimal maintenance (some water was added to the pot at the 15 minute mark). As one would expect, the power output of the Nomad 7 solar panel was highly dependent on the cloud cover. The solar panel had no trouble producing the maximum 5W of power when the sun was out but failed to produce any power at all when the sun was behind a cloud. This binary nature resulted in an average power output of only 2.1W during the test period. It would take the solar panel twice as long to charge the Guide 10 Plus battery pack in these conditions when compared to the Power Pot!
Granted, you don’t need to use a meter to tell you whether or not there are clouds in the sky. Where the Practical Meter really comes in handy is when you’re trying to orient the solar panel at the proper angle to the sun in order to maximize its power output. This alone makes the Practical Meter a very desirable piece of backcountry gear! Not convinced?? See for yourself…
Overall, I found the Practical Meter to be surprisingly handy and consider it to be a must-have for the tech-savy outdoor enthusiast. This little meter is an extremely powerful tool in that it provides for optimization of portable power generators (thermoelectric and solar) thus conserving fuel and time while recharging your small electronics. It’s important to note that the unit that I tested was only a prototype and I was hard pressed to find any issues with it! Since then, Power Practical has wrapped up the product testing phase and recently launched a Kickstarter campaign to fund production of the Practical Meter! Consider contributing to their campaign to support this worthy outdoor product and be one of the first to get your hands on a Practical Meter when they are released to the market!
Pros: Small profile, easy to use, surprisingly handy
Cons: Low resolution (1W increments)