Nexus Quick Charge Explained

Just when we thought we had this whole “quick charging” thing all figured out and knew which car- and wall-chargers to get, Google went and confused everyone all over again. Yes, it’s true that the new Nexus 6P and Nexus 5X support quick charging, but no, despite both phones being built around Qualcomm Snapdragon SoCs, neither has “Qualcomm Quick Charge” of any variety (1.0, 2.0, or any other version). What they do have is pretty good, if specifications are to be believed (we’ll reserve final judgement until after our full reviews), but there is quite a bit of confusion around what kind of quick charging the new Nexus phones use, and what chargers they’ll work with – and won’t work with. Let’s see what we can do about that and figure out what Nexus quick charging is all about.

First, let’s get some battery charging background out of the way. The analogy we’ve used in the past is to envision the battery as a bucket and the charger as a hose filling the bucket with water. You, the person holding the hose, are the “charge controller” and dictate how much water pressure and volume is allowed through the hose and into the bucket. Too much pressure and it sprays all over the place, without much water staying in the bucket. Too little pressure and filling the bucket takes forever. You have to closely monitor what the bucket can accept, and adjust the flow accordingly as it fills.

Charging batteries works in much the same way, except instead of water it’s electricity, measured in volts, amps, and watts.

Not Qualcomm Quick Charge nor VOOC Flash Charge

When we hear the words “quick charge”, many of us think of Qualcomm’s Quick Charge 1.0 and 2.0 technologies that are embedded into many phones and chargers these days (or even the upcoming 3.0 version). Chargers built to these standards will work with any USB-powered device, though they require circuitry on the receiving end to take full advantage of all that quick-charging goodness.

The concept behind quick-charging is fairly simple: the technology enables charging at multiple rates, syncing and scaling amperage and voltage between the charger and the device being charged to allow for a lot of power to enter the battery quickly – but only when the battery is able to receive it.

Somewhat recently OPPO jumped on the quick charge bandwagon with its VOOC Flash Charge technology, which is similar to Qualcomm Quick Charge. (VOOC stands for Voltage Open Loop Multi-step Constant-Current Charging, just in case you were curious.) One advantage to VOOC is that it moves the charge controller circuitry from the device into the charger. This helps move the heat involved in the process from the handset to the wall. As heat in a circuit goes up, so does resistance – reducing its efficiency. By moving the heat from the small confines of the phone and putting it at the other end of the cord, the efficiency is improved – theoretically.

The quick charge functionality that comes on the new Nexus 6P and 5X doesn’t use Qualcomm’s or OPPO’s quick charge technologies. As such, according to a Google Engineer, chargers built to these standards “won’t work” with the new Nexus phones. We presume this means they won’t work at quick-charge rates with the new phones, rather than meaning they won’t work at all. (We hope that’s the case, anyway.)

It’s not USB 3

usb-3-cableNext up is USB 3.x.

Yes, USB 3.x offers faster charging than USB 2.1, but the new Nexus phones only support USB 2.1, even though they have that super-sexy USB Type-C charging port.

USB 3 (specifically the “microUSB” Type-B connector looks like the one illustrated above, with a standard microUSB connector married to another connector. The reason for this configuration was to allow “regular” microUSB Type-B cables to work with the devices – although without any of the benefits of USB 3.x (faster charging and faster data throughput paramount among them).

This type of USB 3 connector has been seen on a few phones. Despite its extra bulk and less-flexible cable, it worked great on the devices that featured it. Alas, it’s awkward form factor was its undoing, and paved the road for USB Type-C.

USB Type-C

USB 3.1 Type C connectorUSB Type-C is an interesting anomaly on the USB roadmap.

As outlined by the USB Type-C Cable and Connector Language Usage Guidelines, if a product supports USB Type-C, it does not necessarily support the USB 3.1 or USB Power Delivery specifications.

USB Type-C works with the USB 2.x and USB 3.x specifications, which explains why your device might not have all the technical advantages if it includes a USB Type-C, but doesn’t include support for USB 3.1. For example, the Nokia N1 (one of the first hardware products to support USB Type-C), only supports USB 2.0 (not even USB 2.1).

You will, however, get some advantages, regardless of which version of USB is flowing through the cable with USB Type-C.

  • USB Type-C connectors are reversible – there’s no more upside-down or rightside-up – either way works equally as well.
  • USB Type-C to USB Type-C cables are reversible end-to-end as well, and this type of cable is compatible with the full USB 3.1 feature set. USB Type-A to USB Type-C cables may only support USB 2.1, so you’ll want to make sure you know what you’re buying – and saving a few bucks on a cable may mean it’s only USB 2.1 – and not future-proof for all the cool things USB 3.1 can do.
  • USB Type-C also has a distinct advantage over other types of USB, namely its power delivery capabilities – which is why you’re reading this article.
[table] Specification,Current,Voltage,Power
USB 1.x and 2.0,500 mA,5 V,2.5 W
USB 3.x,900 mA,5 V,4.5 W
USB Battery Charging (BC 1.2),0.5–1.5 A,5 V,2.5–7.5 W
USB Type-C,1.5 A,5 V,7.5 W
USB Type-C,3 A,5 V,15 W

As you can see, USB Type-C allows for some of the same charging characteristics of Qualcomm’s Quick Charge and OPPO’s VOOC, but it’s an industry standard, not a proprietary one fighting for the “defacto standard” title.

That’s how the Nexus 6P can boast “up to 7 hours of use” and the Nexus 5X “up to 3.8 hours of use” from only 10 minutes of charging. So, there you have it, Nexus quick charging explained. Any questions?

Nexus 6P what's in the box text

Joe graduated from Weber State University with two degrees in Information Systems and Technologies. He has carried mobile devices with him for more than a decade, including Apple’s Newton, Microsoft’s Handheld and Palm Sized PCs, and is Pocketnow’s “Android Guy”.

By day you’ll find Joe coding web pages, tweaking for SEO, and leveraging social media to spread the word. By night you’ll probably find him writing technology and “prepping” articles, as well as shooting video. Read more about Joe Levi here.

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