Speed, Thermal, and Performance Comparison of Fast Charge Standards

OnePlus DashCharge Takes the Crown

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One of the most common qualms from smartphone users is how their phones never last through the whole day. Despite all the advances in smartphones in recent years, such as quick charging solutions like Quick Charge, Dash Charge and SuperCharge, batteries feel like they have not evolved quick enough to keep up with our needs.

Part of the blame goes onto OEMs, who do work towards making our smartphones more efficient year-on-year. But on the flip side, the increasing efficiency of our smartphones are seen as perfect excuses to thin down our phones by yet another millimeter. And to retain the practicality of the phone, advances in the field of charging are advertised as a key feature of the device. So what if your phone dies after 6 hours of standby? Now you can get a day’s power in half an hour, or some other slogan.

Choice, one of Android’s strongest selling points, also ends up confusing users when it comes to charging standards. There are multiple charging solutions available across Android flagships, with their own positive and negatives attributes, intricacies and particularities. Some charging solutions are quick, some are efficient and some aren’t really quite as great as one would expect.

In this article, we will take a look at the performance and efficiency of some popular charging standards, namely Huawei’s SuperCharge, USB Power Delivery, OnePlus’s Dash Charge, Samsung’s Adaptive Fast Charging, and Qualcomm’s Quick Charge 3.0.

Index

Current Winner 9/16/2017

OnePlus Dash Charge

Offering an excellent balance between speed and stability, Dash Charge surprised us with its ability to charge your phone quickly and painlessly. Its custom charging adapter and signature red cable allow newer OnePlus devices to remain cool while charging, without sacrificing performance on device nor charging rates. This means you use your device while it’s getting topped up and keep on messaging, browsing the web or even playing a game. Dash Charge cannot offer wide compatibility or a diverse set of charger options, but in the end it provides an excellent charging solution that does not get in the way of the user experience.

Methodology

The data we collected involved the use of a script that automatically measured key charging parameters (as reported by Android) and dumped them into a data file for us to analyze. All charging standards were tested with their stock charging adapter and cable to ensure that the data is representative of what we can expect from each standard. All data collection began with the battery at 5% and ended with the battery at 95%. To test thermal performance and charging speeds during screen-on use cases, the script looped PCMark tests while the phone was charging to simulate a real-world usage environment; temperature readings are gathered from the OS, and they are not measured externally. For the sake of clarity in this presentation, averaged data was rounded off while preparing the graphs.

Quickest Charging Standard

When we measured the charging times of the popular charging solutions, we came across a peculiar conclusion: USB Power Delivery was the slowest of all fast charging solutions that we tested, at least as implemented on the Pixel XL. This is only surprising because USB Power Delivery is the “standard” pushed forth by the USB-IF standards body, and the one that Google strongly encourages as well — once we look at each standard’s workings further down this article, it’ll make more sense.

USB Power Delivery has been implemented in the Google Pixel and Google Pixel XL. The smaller Google Pixel is marketed at being capable of 15W-18W charging, while the bigger Google Pixel XL is capable of 18W charging. As we noted in our Google Pixel XL review, actual charge times on the device were not competitive, ending up in the last place when compared with other solutions, and our extensive testing on the charging times for the purposes of comparison reveals the same. Below you can see the charging time of each standard from 5% to 80% when scaling the battery capacity across test devices to 3,000mAh — this does not represent how each standard would charge such battery capacity with perfect accuracy, and the graph should be used to get an approximate idea as to how they compare.

When we look at which device charged the fastest, the quickest charging solution we tested is OnePlus’s Dash Charge functionality, which on the OnePlus 3 ends up being quicker than competitors by about 10 minutes in the end (before adjusting for battery capacity), and by a good half hour against USB Power Delivery. On the flip side, Dash Charging is proprietary technology, which adds its own set of complications which we will discuss later on in this article. Dash Charge does end up behind Huawei Supercharge when we take into account, and adjust for, battery capacity in the device, as the Huawei Mate 9 has a substantially larger battery than the OnePlus 3. While Supercharge achieves a faster peak charging rate, the Huawei Mate 9 does not reach 95% charge the earliest because of its larger battery capacity. So while the OnePlus 3 tops up faster in terms of reaching the higher percentages of its battery capacity, the Mate 9 is actually adding more charge per unit of time (a function of Huawei’s higher power delivery ouput).

Huawei Supercharge and Qualcomm Quick Charge 3.0 performed similarly, while Samsung’s Adaptive Fast Charge had less of an initial speed advantage but it still managed to reach the goal of 95% charge while giving close competition to the other two.

We also have temperature data alongside the charging time. This graph coincides with the charge percentage, but had to be separated to keep things simpler, uncluttered and easy to understand.

We were unable to finely control all the starting temperatures of our test devices because of the varying temperatures in the different locations they were tested in, so our focus should be on consistency and stability rather than the absolute highs and lows displayed by each data set. Battery temperature was obtained from Android’s low-level system record of battery temperature.

The most thermally consistent of the lot is Samsung’s Adaptive Fast Charging as it maintains a good hold over the device temperature throughout the entire session. Qualcomm’s Quick Charge 3.0 was the “coolest”, though again, we would need better-controlled initial conditions with perfect starting points and minimal extraneous variables to crown it the king. Similarly, we cannot call USB Power Delivery the “hottest”, but it definitely displays the widest range of temperatures. It’s also worth noting that most of these devices end up cooling down once their charging rate begins slowing down, and USB-PD does a good job at managing temperature past its peak.

The situation changes when you look at how these technologies perform when the device is subjected to a real-world workload. As stated before, we looped PCMark’s Work 2.0 test to simulate real-world usage while charging these devices, in order to measure how charging times and temperatures differed.

OnePlus’s Dash Charging remains as the top performer primarily because of its implementation, which we’ll detail further down. The voltage and current regulating circuitry is situated in the Dash Charger, which leads to lower temperatures while charging. So Dash Charge’s idle-charging and under-load charging scores tend to show very little variation.

On the other hand, Samsung’s Adaptive Fast Charging shows the worst performance when subjected to charging under a real-world workload. The device takes about twice the time to charge if it is being used, and the charging also increases in a peculiarly linear fashion (given voltage and current remain constant) that is not seen across any of our other tests. In fact, according to Samsung’s support page for the S6, its Adaptive Fast Charging solution is entirely disabled when the screen is on. Express mentions like these could not be found on newer support pages, but Samsung continues to recommend devices to be switched off while using Fast Charging.

Other standards continue to occupy positions between these extremes, most lying on the better side of the scale. Even USB Power Delivery, the worst performer of idle-charging takes just about 10 minutes more to achieve the same charge levels under load.

Temperature-wise, Samsung’s Adaptive Fast Charging (if we can call it that under this test) maintains a consistent range of temperatures, flowing within a 5°C range. Huawei’s Supercharge follows along next, followed by OnePlus’s Dash Charge. Qualcomm’s Quick Charge 3.0 and USB Power Delivery are the worst performer temperature-wise with large inconsistencies and variations throughout their cycles.

With inter-standard comparison out of the way, let’s take a closer look at how the standards performed individually under idle-charging and load-charging scenarios, with a short explanation as to why they behave this way and how they work.

Huawei Supercharge

Huawei’s SuperCharge is one of the more interesting standards we’ve tested, showing impressive results under most conditions. Unlike traditional high-voltage charging solutions, Supercharge employs a relatively low-voltage and high-current formula that aims to maximize the amount of current going into the device, while minimizing efficiency losses, heat, and throttling. Coupled with the Smart Charge protocol, the Mate 9 also adapts its charging parameters based on the requirements of the battery, as well as the charger supplied (for example, it can make full use of a USB-PD charger). The actual Supercharge charger comes with 5V 2A, 4.5V 5A, or 5V 4.5A (for up to 25W, or a common 22.5 throughout the most relevant segment) and uses a chipset in-charger to regulate voltage as well — this means that there is no additional in-phone voltage transformation, in turn reducing temperature and efficiency losses. Coupled with what Huawei calls “8- layer thermal mechanics” in its design, the Mate 9 promised fast charging speeds at low temperature. Focusing on current over voltage, and going for a less-lopsided distribution is similar to the Dash Charge standard’s approach, and in many ways both OnePlus (or Oppo’s) solution is similar to Huawei’s Super Charge.

Looking at the data we’ve gathered, we see the typical pattern of temperature beginning to go down past the 55% mark, the point at which current begins dropping off as well. Peak current comes close to the 5A rating of the charger, and sustains the 4.5 nominal current throughout the first 20 minutes, or until around 45%. The fastest charging rate occurs from 10% to 5%, with a linear slope that begins curving at that current drop-off, where voltage starts remaining somewhat constant after a fast climb from 2V to over 3.5V. Throughout this test, peak temperature hits 38° Celsius, which is significantly hotter than most other standards in this list. However, temperature will become really important when we take a look at our “under load” test, where we simulate activity on the device to compare charging speeds. We can clearly see temperature decreasing alongside the current, which doesn’t drop in clearly-defined steps as other standards in this article, but with a set downwards trajectory

In terms of charging speed, Huawei SuperCharge arrives to 90% in about 60 minutes, putting it second in in terms of speed behind OnePlus’ Dash Charge. However, the Huawei Mate 9 we tested also has a 4,000mAh battery, which means the mAh per percentage are higher than on all OnePlus devices, actually putting the standard in a better light and ahead of OnePlus. There are differences, however, in terms of charging speed, as Super Charge begins leveling off harder than Dash Charge at the 30 minute mark. Most of these companies advertise how much battery life one can obtain in half an hour, and Huawei’s claims were surpassed by our testing as the device managed to climb past 60% in that time period.

Under workloads, the rate of charging naturally is lower than during idle charging. Instead of a steep drop off, we see a more relaxed curve that trails off at around 75%. Current and temperature drop off is experienced when the device approaches 60%.

OnePlus Dash Charge

One of the newer champions of fast charging is Dash Charge, which surfaced in 2016 with the OnePlus 3. While the OnePlus 2 had disappointingly long charging via a regular 2A charger, the OnePlus 3 brought what OnePlus called “exclusive technology [that] sets a new benchmark for fast charging solutions”. As with most marketing statements from OEMs, this is only half true. Dash Charging technology is actually licensed from OPPO, which OnePlus is a subsidiary of, and mimics their VOOC charging system — Voltage Open Multi-Step Constant-Current Charging. While Dash Charge is a much better name, VOOC charging can be found on OPPO devices like the R9 and R11, though in this article we are focusing on Dash Charge as implemented on the OnePlus 3 / 3T and OnePlus 5.

So what’s special about Dash Charge? Not unlike Huawei SuperCharge, it produces a larger electrical current of 4A and at 5V for 20W power delivery. Rather than increasing voltage, OnePlus opted for a more even distribution with larger electrical current, meaning more electrical charge delivered per unit of time. This is accomplished via both software and, primarily, through hardware — specifically the charger used, which is non-standard (unlike the plethora of QC chargers, for example) and thus you need a VOOC or Dash Charger to make use of these charging speeds.

Much like Huawei’s solution, OnePlus employs dedicated circuitry in the charger itself, and both VOOC and Dash Charge deliver higher amperage thanks to many components of the charger, including a microcontroller that monitors charge level; voltage and current regulating circuitry; heat management and dissipation components (that contribute to a 5-point safety check); and a thicker cable that delivers greater current, specializing in minimizing power fluctuations. Because the charger converts the high voltage from your wall into the lower voltage the battery requires, most of the heat from this conversion never leaves the charger — in turn, your phone remains cooler. The consistent current going into the phone coupled with the lower temperatures on the actual handset allow for reduced thermal throttling, which impacts both charging speed and consistency as well as the direct user experience.

OnePlus proudly proclaims it can give you “a day of power in half an hour”, which in reality means you are looking at around 60% of battery capacity in 30 minutes. This is not only extremely fast, but there are also a few perks that come with it. The charging speed is fastest and one of the fastest at those lower percentages, ensuring you can get extreme amounts of charge in just a few minutes should you be running low on battery. Moreover, the thermal consistency and lack of throttling is no joke. As we can see from the data supplied, the difference between under-load charging and regular charging is minimal. And this does mean that you will not notice slowdowns, additional stutter or general throttling side effects whilst using your device. This is a great plus and, as we’ve noted in a past analysis, it does truly mean you can play demanding 3D games such as Asphalt 8 while still getting nearly the same charging speed, with the difference being explained by the drain incurred by gaming itself.

Dash Charge does have a major disadvantage, and that’s compatibility. The OnePlus 3 and 3T, for example, are not able to fully utilize USB-PD should you not have a Dash Charge cable and charger handy. And you need both the charger and the cable to make Dash Charge work its magic. Unlike with Qualcomm Quick Charge, you won’t find multiple charger offerings and accessories from various suppliers — you are stuck with OnePlus and their stock, which includes regular chargers and also car chargers (that have been known to be out of stock in regular and somewhat frequent intervals). You could try getting your hands on a VOOC charger, but that’s arguably more difficult in many markets. There’s also a noticeable and disappointing lack of battery packs supporting Dash Charge speeds, as OnePlus offers none — you could try OPPO’s power bank with an adapter, but this is far from ideal.

If you can look past those inconveniences and incompatibilities, Dash Charge is a clear winner in both speed and consistency. It’s a charging standard that does its job quickly and efficiently, without tying down the users to a wall for long periods of time, and without hindering their real-world usage while plugged in. The heat reduction could even lead to increased battery longevity. Your phone will remain cool, but your charger will not — so just make sure not to touch it while it’s doing its thing!

Qualcomm Quick Charge 3.0

Qualcomm Quick Charge is by all accounts the most popular charging standard in this list, and for good reason. Its paradigm is different than what we see with OnePlus and Huawei, because most of the magic happens through Qualcomm’s power management IC, their SoC and the algorithms they employ — all of this enabled Quick Charge to be a relatively low-cost solution (to OEMs) who are already packing a Snapdragon chipset in their smartphones anyway, and while it might not be as impressive as some of the dedicated solutions in this list, the reach of Qualcomm Quick Charge comes with its own set of benefits. While we are focusing on Quick Charge 3.0, keep in mind Quick Charge 4.0 is already available with considerable improvements. The latest revision is also compatible with USB-PD, as strongly recommended by the Android Compatibility Definition Document.

Quick Charge 3.0 has been offered in chipsets including the Snapdragon 820, 620, 618, 617 and 430, and offers backwards compatibility with previous Quick Charge standard chargers (meaning you can benefit from a plethora of lower-cost, slower chargers). This is mainly because the power draw is handled entirely on-device, with you only needing to provide a charge capable of supplying the requisite current to make use of its advantages — there’s no shortage of Quick Charge-certified chargers, so it shouldn’t be hard to stumble upon one. But again, we should re-emphasize that Quick Charge 3.0 even allows a phone to charge faster or more efficiently than non-Quick Charge devices while using a non-certified charger, precisely because so much of what makes it tick is independent of specific charger hardware, unlike Supercharge and Dash Charge.

Quick Charge 3.0 makes use of ‘Intelligent Negotiation for Optimum Voltage’ (INOV), and as the name suggests this allows for intelligent voltage control in order to determine the most efficient voltage, for the most efficient power delivery, at any given point while charging. This coupled with a higher voltage than competitors does allow the standard to expedite charging time, while preventing overheating and ensuring battery safety. INOV is also a step up from Quick Charge 2.0, which had rather discrete power modes of 5V/2A, 9V/2A, 12V/1.67A and 20V); instead, this revision allows for fine-grained voltage scaling, anything from 3.6V to 20V in 200mV increments. By determining which power level to request at any point in time, QuickCharge also prevents damaging the chemical composition of the battery while still providing an optimum charging speed taking into account factors like temperature and available power output. A potential downside is more inconsistency in charging speeds across charging scenarios and chargers, and the improvements do manifest in the earlier stages of charging and a noticeable decline around the 80% mark.

Still, looking at the graphs provided, one can see the finer granularity and wider range of voltage steps are clearly being taken advantage of. It’s worth noting that the Quick Charge 3.0 samples shown here do not behave as efficiently under load as other alternatives that offload much of the voltage conversion and heat dissipation to outside hardware; it’s more than serviceable if you want to use it while charging, however we don’t see the lack of throttling and heat buildup found on solutions like Dash Charge. And, unlike with other standards, you really won’t have a hard time finding power banks that’ll provide the rated charging speeds — this isn’t the case for SuperCharge or OnePlus, unless you are willing to spend more money, spend more time, or make extra concessions.

It’s precisely this level of versatility and support that make Quick Charge a great standard, and some OEMs do ultimately rebrand it as a superior “customized” alternative. But in the end, Quick Charge is an excellent solution for most OEMs looking to implement fast charging that’s efficient, highly compatible, and does not need special accessories. This holds extreme significance given Qualcomm is essentially granting the option to provide faster charging to dozens of smaller OEMs, or of bringing faster charging to mid-range devices through mid-range chipsets. This, in turn, improves the minimum baseline of fast charging offerings, in turn promoting competition and prompting those brands that do offer fast charging as a specific selling point to aggressively improve or market their solution.

USB Power Delivery

USB as a standard has been evolving for years, from a simple data interface that eventually became widely-used as a constrained power supplier, to a fully-fledged primary power provider alongside a data interface. Many small devices have featured USB charging for years, and you probably have a handful of peripherals being powered up by USB cables right at this moment. Power management in the initial generations of USB, however, was not meant for battery charging — rather, it was cleverly exploited for that by manufacturers who saw the slow power delivery was enough for the small batteries of their products. Since then, we’ve seen a tremendous jump — from the USB 2.0 power source of 5V/500mA (2.5W), to USB 3.0 and 3.1’s 5V/900mAh (which was very, very underutilized on Android) and finally, USB PDs 100W charging maximum.

Of course, smartphones have no need (and cannot take in!) such power draw — while 20V/5A is a peak for USB PD, actual chargers see a much lower specification with our tested Pixel clocking in at up to 15W (5V/3A), and the Pixel XL up to 18W. In most charging circumstances, however, voltage goes up to 5V with current sitting just under 2A, with the highest power draw we found during charging being just under 12.25W. As shown in the data provided here, USB-PD really isn’t the fastest charging standard, nor does it offer the best thermal consistency/lack of throttling. It does charge quite quickly under load, however, and overall it offers a very satisfactory – if unspectacular – charging profile.

It is, however, an extremely versatile standard that’s relatively easy to implement and that’s increasingly being pushed forth by Google in products like the Pixel C, Pixel Chromebooks, and Pixel smartphones as well as by various other manufacturers for laptops and other devices of varying sizes. Moreover, USB-PD is now part of the Android Compatibility Definition Document. Last year, the following entry made the rounds because it showed Google’s commitment to the standard, and what many interpreted as discouragement of proprietary solutions.

Type-C devices are STRONGLY RECOMMENDED to not support proprietary charging methods that modify Vbus voltage beyond default levels, or alter sink/source roles as such may result in interoperability issues with the chargers or devices that support the standard USB Power Delivery methods. While this is called out as “STRONGLY RECOMMENDED”, in future Android versions we might REQUIRE all type-C devices to support full interoperability with standard type-C chargers.

Since then, we’ve seen Qualcomm adopt USB-PD spec compliance with their Quick Charge 4.0 release for newer Snapdragon chipsets, which is a huge victory for both Google and Qualcomm. The increasing proliferation of USB-PD and Type C ports can lead us to a future where we see more device interconnectivity, with a near-universal port for audio, video, data transfer and charging needs. USB Type C devices like the Pixel XL currently allow the option to charge other devices using their battery as a power source, for example, and widespread USB Type C and USB-PD adoption in other devices such as laptops could lead to more convenient charging and cable-management use cases.

There’s also no shortage of charger options available for USB-PD devices, and if the standard can co-exist with proprietary standards, that opens up even more possibilities for device manufacturers. As it stands, though, it’s not present in many Android devices yet, with the Pixel and Pixel XL leading the charge. For these two phones and their adequate battery capacities, the charging rate and resulting times are sufficient, and Pixel / Pixel XL owners have multiple options at their fingertips — one just needs to make sure the charger is able to meet the 9V/2A or 5V/3A requirements of the phone, and that it meets specifications. With the emergence of USB Type C and USB-PD, we did see a few reports of potentially dangerous cables being sold online, as they didn’t meet the specifications of the resistor in the cable, for example. Luckily such issues are disappearing and if you make sure to research your purchase properly, you should be OK. Keep in mind that the standard is scaleable, and there will be more voltage and current configurations that OEMs can experiment with.

Adaptive Fast Charging

Adaptive Fast Charging has been Samsung’s preferred charging solution for many years and, unfortunately, it has largely stayed the same since. While our results show that it’s one of the slowest (yet more stable) standards, Samsung opts for it year after year over either a charging solution more in line with what OnePlus and Huawei are doing, or the proper Qualcomm Quick Charge (however, Samsung devices can make use of Quick Charge chargers for fast chargers!). The latter is a consequence of their split chipset strategy, given that their Exynos chipsets wouldn’t be able to take readily take advantage of Qualcomm’s charging technology. Samsung’s Adaptive Fast Charging is thus present in their devices across the globe, and limited to Samsung devices.

While Adaptive Fast charging is faster than USB-PD when adjusting for battery capacity, it’s still significantly slower than Supercharge and Dash Charge, and slightly slower than Quick Charge. It features a peak power delivery of 15W (5V/3A) which is in line with other standards, but Samsung seems to be quite conservative with its charging times — this is particularly evident when charging under load, as the charging rate becomes nearly linear, and has the slowest charging rate out of all devices we’ve tested for this article. That being said, the temperature difference is also the smallest of the bunch, and throttling the charging speeds and minimizing temperature led to consistent performance under usage.

Under both circumstances (regular charging and charging under load*) Samsung’s solution is the slowest (without adjusting for battery capacities) and the coolest (or, rather, features the smallest range of temperatures). This emphasis on stability and consideration for thermals is now more important to Samsung more than ever, after what happened with their Galaxy Note 7 and its faulty batteries. While there might be no correlation between this approach to fast charging and this incident – after all, as we’ve mentioned, their standard has remained largely constant over time – it’s still worth considering that a safer approach to fast charging is not bad in and of itself.

This is especially true for Samsung devices, which also provide an additional different rapid charging solution altogether — fast wireless charging. While conventional wireless charging was gaining popularity a few years back, Samsung is one of the few that stuck with it and then improved upon their implementation by adopting faster wireless charging, which originally cut down charging times from around three hours to just around two. Having this alternative can make up for some of the disadvantages of Adaptive Fast Charging, given wireless charging is a more passive approach that is less cumbersome and thus allows for more regular charging intervals, effectively taking the hassle out of topping up a phone around an office or bedroom space.

* You might notice that the intervals between points in these data sets are smaller than on other stubs and graphs. While gathering data from the GS8+, we stumbled upon a device-specific issue that prevented the PCMark test with UI automation from being carried out properly. We thus revised our data collection and automation tool for the GS8+ and improved the polling mechanism while we were at it. Data added in the future will benefit from these improvements resulting in more accurate or smoother graphs.

This article will be continuously updated as we get our hands on more devices, and get to test newer or updated standards. Stay tuned for more comparisons!