Have you ever got a warning on your phone that the power incoming when plugged in is less that the power being used? It happened to me recently on a Delta jet and it got me thinking just how much power i.e. volts and amps do the different USB ports we plug into when we travel really provide? Notice what “Wired.com” tells us:
“Ultimately, it’s really the amperage that determines how fast a charger will supply power to your device. If you want quicker charging, look for a wall or car charger that delivers 2100 mA of current at 5 volts (or whatever voltage the device you’re trying to charge is specced at).”
First some baselines and some methodology these numbers and tests are from my phone. For example, the max I am drawing with my Samsung Note 4 from home and plugged into power is what you see above.
The same goes from my sweet mega battery brick. Both wall and battery should push 2 amps but clearly my phone does not pull that full amount. The point is that I consider the above numbers “full” power and the other results will be based on these baseline numbers.
I thought I would first test stuff around my house with this simple DROK 300043 USB 2.0 Digital Multimeter, Ammeter Voltmeter Capacitance and Watt Meter on devices like my computer USB power port. I rarely use it to provide power as it did seem slow and now I know why as both the voltage and amps are ~36% of the wall power.
Next on to my laptop USB port as I do often plug into this when I am tethering my Sprint PCS internet service to my laptop. While the voltage is a bit higher the same poor amps are provided. On to tests on the road.
How about some tests at the brand new shiny Delta B Sky Club. There are power ports just all over the place and the in-seat ones as well as the pop-up (or out) ones in the tables are providing solid results. Nice.
Now over to the international concourse and the iconic F club with the Sky Club. Here you will see all over the place power “towers” that have both USB and standard power. While the ports in the tables between the seats was solid notice the lower yield from the towers.
There are also power towers at most of the Delta gates in various hubs. So how do they stack up? Notice the disappointing results from my test in Salt Lake yesterday. Ugg. Next let’s move on to flights as this is really what sparked this whole test effort.
The above is my USB to standard wall outlet power adapter. I was expecting this to provide good power and it did. Not quite what I got at home but respectable results. What about the USB in the seat back on a Delta international A330?
OUCH! – Again we are talking about 36% of wall power! And this I can imagine is why I received the warning from my phone that the needed amperage was not adequate to keep up. Let’s look at a few more.
Again we see only marginally better performance in Delta One on the A330 I flew to Hong Kong and back recently. Thankfully the flight was some 14 hours long so even slow charging got me to 100% after a while.
Last up we have an A320 that has just been reconfigured with the new oversized overhead bins. Again, less than exciting results from the USB ports.
So what should you take away from all of these many tests? Clearly just how much “juice” you get will depend on where you plug in – that is, all USB power sources are not created equal and you may not be charging as fast as you think. Next, if at all possible, you will yield the best results using a wall to USB power adapter or a good output battery brick to charge your phone.
You may have on your own already come to the exact same conclusions from trial and error but at least now you have more data points to show you were spot on with your assumptions.
Before I sign off for the day I am no expert in electronics but thought this post would be useful. If you such an expert feel free to comment but please be nice 😉 – René
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