Not all Micro USB cables are equal: if you have a tablet, watch out for 28/28 AWG vs. 28/24 AWG

Photo: Daniil Vasiliev, CC BY-SA 2.0
Photo: Daniil Vasiliev, CC BY-SA 2.0

I somehow misplaced the Micro USB cable that came bundled with my Nexus 7. Earlier today, I plugged it in to charge using a different cable– and to ensure it would charge as quickly as possible, I even shut it down before plugging it in. After four hours, I came back to discover that the battery had only crept up from 4% to 32% in those four hours. My Nexus 7 was charging incredibly slowly.

It turns out that the Nexus 7 comes bundled with a Micro USB cable with wire gauges of 28/24 AWG. That means normal-size data wires (28) and large-size power wires (24).

Normal Micro USB cables are 28/28 AWG, meaning that their power wires are significantly smaller than the special 28/24 AWG charging cable. (Unintuitively, “28” is a smaller size than “24.”)

It’s not just tablets that require 28/24 AWG cables. Newer, larger smartphones benefit significantly well from 28/24 cables as well due to their increasing battery capacities and power demands.

If you’re in a hurry and need Prime shipping, Amazon sells some decent 28/24 AWG wires (three feet, six feet).

Update, June 2014: These are the cables I’ve been happily using since I posted this entry about a year ago. Amazon has turned many cables into “add-on items” instead of normal Prime items, but you still get Prime-speed shipping if the cable is part of a large enough order.

(If you cannot see the USB cables displayed above, you may be using an ad blocker that blocks Amazon links. Try disabling your ad blocker and reloading the page.)

If you’d like to buy cables in bulk and don’t mind waiting a few extra days for delivery, Monoprice has lower prices, though you do have to pay for shipping. Just be sure the description specifies 28/24 AWG before buying your USB cables!

Addendum, June 2014: I also picked up this awesome charger a couple months ago:

It works excellently with my high-capacity 28/24 AWG micro USB cables. The charger can put out up to 2.4 amps per port for any kind of device, whether Apple or Android, and can intelligently shift around that amperage and switch between your devices’ preferred charging methods depending on what you plug into it. It’s given worlds better performance than the crappy AC adapter wall plugs that come with most devices, and it’s been great for travel, too. Just one power outlet at the airport or a hotel room is sufficient to power five devices at a time, and the charger can handle input from 100 to 240 volts, making it ideal for international use. I don’t usually “push” a device this hard, but I’m seriously in love with this charger. If you’re investing in good 28/24 AWG USB cables, you owe it to yourself to get a flexible, powerful charger that will last for years to come, too.

Update, 7/22/14: Ironically, the Anker charger listed above actually failed me recently! Three of the five USB ports died. However, upon closely examining the (still excellent) Amazon reviews, I saw that a few customers had the same issue, and that it seems to be tied to a specific manufacturing batch. I contacted Anker to let them know about the problem with my unit, and they immediately arranged to ship me a free replacement. They didn’t even ask me to return the defective unit, only requesting that I tell them its serial number:

Dear Bill Price,

Thank you for getting back to us with the serial number, which can help us to identify the batch number so we can calculate the defective rate to better control the quality.

Kindly please be advised we have arranged the replacement charger to you for retry. It will be shipped out next business day. Hope you can get it soon.

Any other concerns we can address, please feel free to contact us.

Reference [ticket number redacted] if contacting a CSR by phone.

AnkerDirect Customer Support
Mon-Fri 9am to 5pm(pst)

I thought the customer service was good enough to highlight! Turns out they have an 18-month warranty, so even if the replacement somehow fails, I’m not too worried.

September 7, 2013Permalink 9 Comments

Just finished OER-101, SUNY’s free online course on Open Educational Resources

The open course on Open Educational Resources run by SUNY‘s “Open SUNY” initiative is still active. I took my sweet time with the final one or two tasks, but it’s finally finished:



Any educator can benefit from using (and making!) open educational resources, so I still highly recommend checking out this free course.

Google Chromecast: awesomely fun and awesomely cheap, but not ready for the classroom

Photo: Erica Joy, CC BY-SA 2.0
Photo: Erica Joy, CC BY-SA 2.0

The new Google Chromecast is a dirt-cheap ($35) device that lets you wirelessly beam video from a computer, tablet, or smartphone to an external video device like a TV or projector. It’s similar to an Apple TV in its functionality.

The device itself is a tiny dongle that connects to a TV, monitor, or projector via an HDMI plug. It can draw power through the HDMI plug if your device supports that; otherwise, it’s powered through a Micro-USB port.

You use the Chromecast by pressing a little “cast” icon inside of your Chromecast-supported web browser or smartphone app. Once the button is pressed, video either streams from your device to the Chromecast (e.g., if you are mirroring your web browser) or directly from the Internet through the Chromecast (e.g., for Netflix or YouTube videos). In the latter case, your device becomes a remote control to pause the video, raise or lower the volume, toggle subtitles, and so on.

Using Chromecast on Android. From left to right: Netflix's browsing interface with the new "Cast" icon near the top right; the "Cast" selection screen; and the remote control interface.
Using Chromecast on Android. From left to right: Netflix’s browsing interface with the new “Cast” icon near the top right; the “Cast” selection screen (my Chromecast is named “pajamas”); and the remote control interface with volume control, subtitles control, pause and stop buttons, scrubber bar, 10-second rewind button, episode selector button, and cast button.

I’ve been using a Chromecast at home for a few weeks now. I love it as a consumer device, but as of late summer 2013, I cannot recommend it for classroom use.

The bottom line is that the number of supported apps is still laughably small. You can stream a laptop’s Chrome browser window (albeit in a somewhat laggy and buggy fashion) and thus cast a Google Drive presentation to an external monitor, but tablets and smartphones are limited to just YouTube, Netflix, and Google Play streaming. Thus, it’s still impossible to cast a presentation, photo, or document from a tablet to an external monitor via Chromecast. I would love to be able to take a quick photo of a student’s work and wirelessly project it to the classroom monitor, but that’s currently impossible with the Chromecast. The lack of such basic functionality is a total dealbreaker.

In addition, because the video streaming is wireless, the device requires WiFi to function. If your institution is as finicky about WiFi access as mine is, that’s also an enormous administrative hurdle. I would not be capable of testing out my personal Chromecast in the classroom even if I wanted to due to the WiFi access issue. And because the device currently has no security, any student who has access to the same WiFi network can cast any media to the Chromecast at any time–which is an acceptable risk in a classroom full of adults, I think, but it’s an obvious non-starter in a primary or secondary school.

Right now, the Chromecast is a neat toy and an awesome consumer device, but until its software matures enough in terms of security of access and in terms of what materials can be wirelessly projected to your display, it’s essentially worthless in a classroom context. And even then, if your district or institution is anything like mine, it would take a considerable administrative push to get the device implemented in the classroom due to the fact that it requires WiFi authentication.

I love the idea of the Chromecast, and I love owning one. I just can’t imagine a compelling way to use it in the classroom. The device has so much potential, but as it exists right now, it’s weighed down by too many limitations to be worth implementing.