Tag Archives: USB

USB Charging Cubes and Cables: Bill’s tests prove that not all are created equal

Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who shares the following guest post:

Power Cubes and USB Cables Multiply Like Rabbits

by Bill Hemphill (WD9EQD)

If your house is like mine, you have a box or drawer somewhere that has a tangle of 5V power cubes and cables.  This is what one of my drawers looks like:

And yes I do have two full drawers.

Every new toy I receive comes with another cable and a power cube.  With Christmas coming, we can all look forward to even more of them.

But I have learned  that not all power cubes or cables are created equally.  Earlier this year I realized that sometimes my tablets would take forever to charge and other times they seemed to re-charge a lot faster.  That got me wondering what was causing the difference. I found that switching power cubes or switching cables could make a difference.

I decided to try some experiments.  First I acquired a couple of Drok USB testers.  These are small, inline, digital USB voltage and amp testers.  They clearly show the amp draw and the voltage being furnished to the device being charged.

Second step was to gather up my power cubes and test them against a device that would load the cube close to it rated capacity.  I quickly found that ANY power cube I owned that was rated at less than 1 amp at 5 volt was not capable of providing anywhere near their rated capacity.  Some would drop all the way down to 4.11V at 0.47A. So I made the decision to throw away ANY power cube that was rated at less than 1 amp at 5 volts. That trimmed down the total number.

I proceeded to label each of the remaining power cubes from 1 to 10.  Following is list of the cubes with their power rating:

Note:  Power cubes 8, 9 & 10 have two USB ports.  I had purchased these so that I could charge two devices at once.  I had also thought of using them to power two Raspberry PI computers.

The following tablets were discharged down to less than 15% capacity:

  • Amazon Fire 10” HD Android Tablet
  • Amazon Fire 8” HD Android Tablet
  • Winbook 8” Windows 10 Tablet

Typically the Fire 10” and the Winbook will draw about 1.8 amps when charging.  The Fire 8” draws slightly less than one amp. So they would make great test subjects to exercise the capability of the power cubes and cables.

I tested several of my cables with the Winbook to make sure that the cable used for testing would provide the amps and voltage.  I then tested each of the power cubes using that cable with each of the tablets and got the following results:


  1. All the cubes performed very well within their rated capacity.
  2. It’s interesting to see how the 1 amp rated cubes did with a higher draw.
  3. It’s clear that the cubes do NOT have limiting to their rated capacity.  I would have thought that the 1 amp cubes would have been limited to providing up to but not over that amount.
  4. Likewise, I would have thought that the tablets would limit amp draw when the voltage drops below 5 volts.

Next test was to see if the selection of cable makes a difference.  I randomly selected some cables and labeled them. I used one of the Anker power cubes since they perform the best.  The results were very interesting:


  1. The cables were of various lengths from 12” to 36”.  Some of the short cables performed poorly and some of the long cables performed very well.  So cable length is not necessary an indication of how it will perform. You have to test it.
  2. All the cables performed well at 0.95 amps.  But some of them could not adequately handle higher loads.
  3. I had accidentally left the Winbook charging, so it was not at maximum charge during the cable tests.
  4. The cables in Red have been thrown away.

I have two special cables that I had purchased.  These were power splitter cables, single USB to two mini USB.  I had used these for a while running two Raspberry PI’s off of one power cube.  But they would reset every so often, so I thought that the splitter cable might not be providing power evenly between the two PI’s.  Time to test my theory.


  1. The a & b denotes each of the legs of the spitters.
  2. It’s pretty obvious that the two legs do NOT provide the same capacity at the higher loads.
  3. These cables will also be tossed away.

Now for some fun testing.  I thought I would try to load the Anker Dual Port power cubes to see if they will provide their rated power on each port.

Very impressive.

And last, I have two Anker large capacity 5V battery packs:

Battery one – Anker Astro E7, Model A1210.  Capacity: 26800mAh. Rated: 4A@5V – 2A max per port.

Battery two – Anker Powercore Model A1277.  Capacity: 26800 mAh. Rated: 4A@5V – 2A max per port.

Update [18 Dec 2019]:  I had received a comment that I didn’t show the Anker Dual Port with both ports fully loaded.

I did another test – this time adding in my Pixel cell phone which draws about 1 amp when not fast charging.

Attached is photo showing the Anker power supply fully loaded:

(Fire 10 & Pixel on one port & Fire 8 and Winbook on the second port)

Port 1: 2.59A @ 5.03V

Port 2: 2.75A @ 5.01V

Pretty good for a cube only rated at 2.4A per port.


  1. Don’t just select a random power cube from that drawer.  Be sure to select one that will provide both the required amp draw at a minimum of 5 volts.
  2. Likewise, don’t just select a random usb cable from that drawer.  Make sure the cable will carry the required current and voltage.
  3. The Anker products that I have (power cubes and batteries) produce the rated current and voltage.  I would highly recommend them.
  4. Where before  I had two drawers full of power cubes and cables; after throwing away about half of them, it has been consolidated into a single drawer.
  5. I may buy some more of the Anker power cubes.

Wow…thank you, Bill!

Your timing is impeccable. I’ve also been weeding out a number of USB power cubes from my own “drawer-o-plenty!” I had been simply looking at the rated amount on each cube and deciding which ones to keep–tossing all of the lower amperage ones. I think I may actually save a little time and simply invest in a few Anker Elite Dual-Port chargers (note this Amazon affiliate link supports the SWLing Post). At present, the white ones are $8.99 each. I especially like the fact that the plug folds and that it automatically switches between voltage standards (100-240 VAC) while travelling between countries.

Side note: I have also been very pleased with Anker’s customer support. I purchased some Soundcore Anker bluetooth earbuds in January–by November they started having issues maintaining a Bluetooth connection. I contacted Anker customer service and after a little troubleshooting, they dispatched a new replacement pair.

Although I know well that not all USB cables are created equally, I would have never guessed there would be much difference in terms of charging ability. Your tests certainly prove otherwise. I suppose I should not be surprised because most “free” USB cables that accompany consumer electronics are of the cheapest quality. I imagine many of the conductors/wires inside those cables are as thin as a hair, hence can’t handle the demands of devices like tablets and larger smart phones.

Again, Bill, thanks so much for sharing this excellent guest post!

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Tripp Lite dual ferrite USB cables

I found this tip from Lorne Waters on the SDRplay Facebook page:

I was having a lot of trouble with local noise and not getting really good signal spikes. Well I took a chance after reading many articles on using better USB cables. The picture below is what I purchased from amazon. It’s a USB with dual ferrite cores mounted at each end. Well this did wonders for me. It’s like less than 10 bucks. Well worth it. Try it for yourself. Using with SDRplay RSP1a.

Click here to view on Amazon.com (affiliate link supports the SWLing Post).

Lorne has a good point. All of my SDR USB cables have at least one in-line ferrite choke. Cables with dual chokes like the Tripp Lite are pretty rare. Note that this USB cable fits SDRs (like SDRplay models) with a USB-B port. I’ve had a difficult time in the past finding dual ferrite choke USB-A to Mini or Micro USB ports. In those cases, I often employ these inexpensive snap-on ferrite chokes.

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Steve searches for a USB-powered battery charger for solar recharging

Many thanks to SWLing Post contributor, Steven Crawford, who writes with the following inquiry:

[I’m searching for] good quality USB powered battery chargers for AA and D size rechargeable batteries.

Wall outlet chargers are common but quality USB powered battery chargers appear much less common…less common than the packable solar panels with USB ports such as Anker’s, that could be used to power them. Ideally the charger should handle Nicad’s, NIMH and Ii-on but have standardized on AA, AA + D adapter sleeves, and D batteries for my storm supplies.

If I understand correctly, you’re searching for a good qualityUSB-powered battery charger that supports multiple battery chemistries (nickel-cadmium, NIMH and lithium ion) so you can recharge AA, AAA and D batteries with a portable solar panel.

I’m hoping SWLing Post readers can offer some suggestions.

I’ve also looked into this type of charger for both Ears To Our World and my own personal use when off-grid in the summer. I’ve never found one that truly supports all of the battery chemistries you mentioned. The one I’ve used (an EBL) works quite well, but only supports NiMH AA and AAA batteries. As you mentioned, you can use D cell sleeves with the AAs.

EBL makes a number of USB chargers that can be found by searching Amazon. This one–an EBL Quick Charger (affiliate link)–can recharge NiMH batteries within 40 minutes and I’ve personally used one. I’ve been pleased with EBL batteries as well.

I never use nickel cadmium rechargeable batteries at this point, so really don’t know what’s available on the market.

I have found that there are a number of USB-powered lithium battery chargers, but typically for specific lithium cell configurations like 18650, 16340, 14500, 26650, etc. Some of these inexpensive chargers have magnetic contacts that can fit almost any battery type and on Amazon and eBay they claim to recharge multiple battery chemistries, but frankly I’m quite skeptical. These $9 devices don’t seem to have a way of detecting battery chemistry, thus I’m not sure how they would adjust the charging cycle accordingly. Perhaps I’m incorrect in this assumption?

Other than using Powerfilm solar NiMH battery chargers (I can recommend these) which are incorporated in their folding panels, I’ve never charged batteries directly from a solar panel. Typically I have a 9ah or larger 12V battery floating between the PV panel and the charger.

I’ve found that using a 12VDC charger–like this–that’s pulling power from a 12V battery is simply a little more efficient, faster and reliable than charging directly from a small PV panel. Since I always have 12V batteries on hand when off grid, it’s a simple solution for for my system.

Post readers: do you have any USB-powered battery charging suggestions for Steven? Please comment!

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SSB Reception Examples with the XHDATA D-808 Portable Receiver

In my earlier article on this receiver, I shared reception videos of three weak medium wave stations and a single shortwave outlet, all demonstrated in AM mode.

These two videos are of reception in SSB. The first example is true SSB reception–in lower side band on the 40m amateur band, while tuning a local on-the-air ham radio classifieds broadcast:

The next video demonstrates “ECSS” reception
(tuning an AM mode signal in SSB). In this example I use a strong station so the audio quality and fine tuning accuracy of the XHDATA receiver can be clearly heard. Typically, ECSS is used by SWLs and DXers for AM mode stations that suffer from adjacent channel interference on one side or the other.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

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USB Battery Pack Keep-Alive Load Kit

(Source: Southgate ARC)

USB power banks are a convenient way of powering low power USB devices in the field. Unfortunately, as they are designed for charging phones and tablets, many have an internal electronic cut out circuit that switches power off below a certain current draw. The exact current that they switch off at varies from pack to pack.

Although there are circuits on the internet that purport to solve this problem by applying a pulsed load, we found this did not work with all power banks. As a result we designed a neat variable electronic load to address this problem.

Available as a kit, using it is easy; just plug it into your power bank, plug your target device into it and adjust the current draw until the pack remains on.


This could be a handy tool for those of us who use USB battery packs for portable work. SotaBeams originally created this simple kit for the WSPRlite.

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