Note, in this post I use AWG (American Wire Gauge) and "gauge" interchangeably. The AWG (gauge) of a wire is a measurement of its diameter or thickness. The lower the gauge number, the larger the diameter of the wire. Lower gauge, larger diameter wires have less resistance and will pass more voltage and current through due to lower losses. Resistance also increases with distance, so longer wires will have more resistance and more power lost than comparable shorter wires. Ideally, you want the shortest, fattest wires you can get for power delivery. Realistically, it would be difficult to connect 2 gauge jumper cables to a Raspberry Pi, so we need to be a bit more practical in our quest to power our little computers.
Typically, Micro-USB cables have 28 gauge wires for both data and power. Really cheap ones might even go as low as 32 gauge. While thin wires don't have much impact on data delivery (data wires can be thin because they don't require much power), they severely limit power delivery to something like a Raspberry Pi3, which needs a lot more power than the older models. Better USB cables will have 24 gauge power wires, and that should be enough for most people, but if you want even more power, here are the Micro USB cables I would recommend.
1. Monoprice Premium USB to Micro USB Charge & Sync Cable
Available lengths: 6 inch (0.5 ft), 18 inch (1.5 ft), 36 inch (3 ft), 72 inch (6 ft)
Wire gauge: 23 AWG power, 32 AWG data, OFC (Oxygen Free Copper) wire
100% compliant with USB 2.0 specifications
Gold plated connectors ensure a smooth, corrosion-free connection
Ultra-thin polycarbonate connector heads fit through most phone/tablet cases
Shielded to protect against external signal interference
I prefer the Monoprice Premium cables because they have very small connector heads that fit into tight spaces better than most other cables. They also have a thin, flexible jacket. They are the most flexible cables on this list (except for the dCables Bendy mentioned at the end), and in spite of their larger 23 gauge power wires, they are more flexible than most cheap cables with thinner wires. They are also the only ones made with premium OFC wire, which has lower resistance than normal copper wire.
The Micro-USB connector clicks firmly into the port on most devices and stays in place, but is still easy to remove when needed. I can hang my large Samsung Galaxy Note 4 "Phablet" phone from the Monoprice Premium Micro USB cable and it will not disconnect, even with a gentle shake.
2. iSeeker Micro USB Cable, USB 2.0 Nylon Braided Cords with Aluminum Connector
Available lenghts: 1 ft, 3.3 ft (1M), 6 ft, 10 ft (in bundled kits)
Wire gauge: 21 AWG power, 28 AWG data
iSeeker's cables are designed with ultra-thick 28/21 AWG diameter tinned copper wires. The description says they have gold plated connectors, but the cables I received did not. Regardless, in my experience they are high quality, durable cables.
The connector heads on the iSeeker cables are slightly larger than the Monoprice Premium cables, but they are still smaller than most. The large gauge wires and thick, nylon braided jacket makes for a relatively stiff cable compared to the Monoprice Premium cables, but when you compare them to typical off-the-shelf USB cables, they are no worse than many others. One of the key differences in the iSeeker cables are the aluminum connector heads, which, combined with the nylon braided wire cover, give them a very premium look and feel. These are the nicest looking cables in the list, with performance to match their good looks.
The Micro-USB connector clicks into place with a firmness comparable to the Monoprice cables, but they are slightly harder to remove. The Micro-USB connector is also slightly longer than the Monoprice connector, so if you have a device that seems to need a bit more reach in the Micro-USB socket (like my Western Digital Passport portable hard drive), these cables should help.
3. Tronsmart 20AWG Micro USB Charging Cable
Available lenghts: 1 ft, 3.3 ft (1M), 6 ft (in kits)
Wire gauge: 20 AWG power, 28 AWG data
Tronsmart cables have an unassuming appearance, much like any off-the-shelf USB cable you'd find at your local big box retail store. In spite of their appearance, they feature large 20 AWG power wires and gold plated connectors. The connector heads are pretty compact, similar in size to the iSeeker cables above. They are also comparable to the iSeeker cables in flexibility.
The Micro-USB connector clicks firmly into the port on most devices and stays in place, but is still easy to remove when needed (comparable to the Monoprice cable, but the larger head is a bit easier to grip). Like the iSeeker cable above, the Micro-USB connector is also slightly longer than the Monoprice connector, so if you have a device that seems to need a bit more reach in the Micro-USB socket, these cables should help.
4. Volutz Equilibrium Series Micro-USB to USB Cable
Available lenghts: 3.3 ft (1M), 6.5 ft (2M), 10 ft (3M)
Wire gauge: 19 AWG power, 24 AWG data
The Volutz cables have the largest wire gauge I have ever seen in a power+data micro USB cable.
Volutz cables also have the largest, easiest to grip connector heads, but due to their unique design, they can still fit into tight spaces (sometimes even better than the tiny Monoprice connector heads). You should have no trouble plugging this cable into a device with a thick case. Note that the connector heads are much longer (almost twice as long as the Monoprice connector head), so if you need a tight bend in the wire near the port, this would not be the cable to choose. In spite of their thick wires and nylon braided jacket, they are remarkably thin and flexible. Not as thin and flexible as the Monoprice cables, but better than iSeeker or Tronsmart.
The Volutz cable also works on my WD Passport HDD, which has an extra deep Micro USB socket.
Now you might be thinking the Volutz cable is the one to buy, but not so fast ... they have the tightest Micro-USB connectors by far. They require a lot of force to insert the plug (excessive, in my opinion), and once plugged in, they can be difficult to remove. If you want a cable for something you will connect and disconnect frequently, I don't know if I would recommend the extremely tight connections of the Volutz cable. However, for something that you will leave plugged in most of the time, this might be the way to go.
Length:
Comparing the actual length of the 3 foot/1 meter cables I found the following.
Monoprice 3 foot measured 37.5 inches (tip to tip).
iSeeker 1 meter measured 39 inches (tip to tip).
Tronsmart 1 meter measured 40 inches (tip to tip).
Volutz 1 meter measured 40.5 inches (tip to tip).
Note that the actual connected length will be slightly shorter than the above measurements.
Performance:
I very much doubt there would be a measurable performance difference in any of the cables mentioned above. In terms of durability, I have only had long-term experience with the Monoprice and iSeeker cables, so only time will tell with the other two. That being said, they all seem very well made, so I don't expect any problems and feel comfortable recommending any of them.
EDIT: I have since done some voltage loss measurements with the following results.
The power supply used for the tests was a RAVPower RP-PC002W with an output of 5.3V from its iSmart port, and it's rated for up to 2.4A. All measurements below are taken from the output of the Pi3 USB ports, so this doesn't represent the voltage loss through the cables themselves, but the loss of the cable + Pi3 system combined.
Monoprice (3ft)=5.15V (-0.15V)
iSeeker (1M)=5.15V (-0.15V)
Tronsmart (1M)=5.15V (-0.15V)
Volutz (1M)=5.15V (-0.15V)
Some additional results:
Monoprice 1.5ft (18 inch)=5.17V (-0.13V)
Monoprice 0.5ft (6 inch)=5.20V (-0.1V)
Monoprice (6ft)=5.12V (-0.18V)
iSeeker (6ft)=5.13V (-0.17V)
iSeeker (10ft)=5.09V (-0.21V)
dCables Bendy (7 inch)=5.07V (-0.23V)
Hapurs cable with switch (5ft)=5.08V (-0.22V)
As I suspected, there was no real difference in the cables above. All of the 3ft/1M cables had the same results, which was less than a 3% voltage loss through the system (remember, this is the loss across both the power input cable and the Pi3 computer itself). The shorter 1.5ft and 6in Monoprice cables reduced the voltage drop to 0.13 and 0.10 volts respectively, so shorter cables are better if you can manage it, but the difference was so small that it's negligible.
The dCables Beny, while short, has narrower wires which offer more resistance to the flow of power, and it shows in the results above. The Bendy was second shortest cable tested, but it had the highest voltage drop at 0.23 volts. That illustrates just how important larger wires are when you need maximum power delivery. That being said, this is a USB 2.0 cable we're talking about, and those are designed to deliver only up to 0.5A (500mA), not the up to 2.5A (2500mA) the Pi3 might need. I have used the Bendy cable with my WD Passport portable hard drive and it works fine. So while it may not be a good choice for a Pi3, it still is a good USB 2.0 cable.
The Hapurs cable with switch suffered more voltage loss than I would have expected, considering even the 10 foot iSeeker cable outperformed it. It would seem that the length alone is not entirely at fault. The switch might be introducing some additional resistance. Whatever the reason, the performance was disappointing. I will probably keep the cable anyway, for use with my Pi-Zero.
Pricing:
My Monoprice Premium Micro USB cables were purchased directly from Monoprice (http://www.monoprice.com), and at the time of this post they were $2.78 for the 3 foot length. They are also available in 6 colors (black, white, blue, green, orange and pink).
My iSeeker Micro USB cables were purchased from Amazon (http://www.amazon.com) in a package of three with one of each length (10ft/6ft/3.3ft) for $9.59, and they are available in silver, black and gold colors in various bundle packages (the 3x1M kit is $8.99).
My Tronsmart Micro USB cables were also purchased from Amazon in a three pack of 1 meter length cables for $6.99, making them the bang-for-the-buck bargain winner in this group ($2.33 each). They are available in black or white in various multi-packs.
My Volutz Micro USB cables were purchased from Amazon as well, and were in a three pack of 1 meter length cables for $8.98. The cables are mostly black with colored accents on the plug ends. The 3x1M kit has one each of red, orange and yellow accented cables. There are several packages for Volutz cables on Amazon (even lightning cables for you Apple fans).
In case anyone is wondering about sample size, I own dozens of Monoprice cables, 6 of the iSeeker cables, and 3 each of the Tronsmart and Volutz cables. I have used both the Monorice and iSeeker cables in the harsh environment of my cars and they have held up well.
Honorable Mention:
There is one other cable I'd like to include as a sort of honorable mention, and that is the dCables Bendy & Durable Short Micro USB Charging Cable, which is 7 inches long (tip to tip). It is a super flexible cable with a soft silicone jacket that is a single molded cover from plug to plug. It is available in a variety of colors from Amazon (click on the picture below to view the product on Amazon).
It is certainly not the best value at $7.99 for a single cable, and it is not the best specs with (as far as I have been able to determine) 26 AWG wire. It's just a cool little cable that looks good in all the fun colors, and feels good in the hand. And due to its short length, it should perform okay even with the thinner gauge wire. Mine has seen a good amount of use in the 2+ years I have owned it, and it has always worked for me. Probably not the best choice to power a Pi3, but for normal USB 2.0 duties it should be fine. I have used it with my Western Digital Passport portable hard drive, and it has worked well.
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