what is quick charge 2.0
What is quick charge?
From 10,000 feet, Qualcomm’s quick charge is designed to safely draw as much power as possible from
the power supply, in order to charge the battery as fast as its chemical components can support it.
Unlike what is often shown in movies, charging faster isn’t only a matter of providing “more power”. You
have to make sure that it can be done safely, since batteries are known to explode or catch on fire under
specific conditions.
Also, since charging and discharging a battery is based on chemical reactions, there are no commercial
applications that can miraculously charge batteries in seconds. Finally, increasing the density and voltage
also comes with trade-offs concerning the longevity of the battery, so this is a delicate trade-off.
Qualcomm says that Quick Charge can charge about 75% faster than conventional chargers. Our tests
show that the claim is true, and to add some context, Qualcomm is about 75% faster than regular chargers
with a 5V 1A electrical output, which is already much more powerful than the plain 5V 0.5A USB.
Quick Charge 2.0 chargers can support 5V, 9V or 12V (volts) and up to 3A (Ampere) and 60W.
Quick charge 1.0 could support 5V and 2A (10W). Many chargers on the market support 5V 1A,
and standard computer USB ports output a minimum of 5V, 0.5A. There are many more variations
that land somewhere in between.
| Support quick charge 2.0 mobile phones | ||
| Asus Transformer T100 | Asus Zenfone 2 | Droid Turbo by Motorola |
| Fujitsu Arrows NX | Fujitsu F-02G | Fujitsu F-03G |
| Fujitsu F-05F | Google Nexus 6 | HTC Butterfly 2 |
| HTC One (M8) | HTC One (M9) | Kyocera Urbano L03 |
| LeTV One Max | LeTV One Pro | LG G Flex 2 |
| LG G4 | New Moto X by Motorola | Panasonic CM-1 |
| Samsung Galaxy S5 (Japan) | Samsung Galaxy S6 | Samsung Galaxy S6 Edge |
| Samsung Note 4 | Samsung Note Edge | Sharp Aquos Pad |
| Sharp Aquos Zeta | Sharp SH01G/02G | Sony Xperia Z3 |
| Sony Xperia Z2 (Japan) | Sony Xperia Z2 Tablet (Japan) | Sony Xperia Z3 Tablet |
| Sony Xperia Z4 | Sony Xperia Z4 Tablet | Xiaomi Mi Note Pro |
| Xiaomi Mi 3 | Xiaomi Mi 4 | Xiaomi Mi Note |
| Yota Phone 2 | ||
How it works?
Most fast-charging technologies work in the same way: draw more power, safely. To achieve that, QC is
relying on two mechanisms:
1. A quick-charge enabled phone will always try to draw as much power as it can, whether the power
source is QC-certified or not
But it won’t ever draw more than 2A, for safety reasons
2. A QC power supply can be identified by a QC-enabled phone, which ensures that drawing up to 3A is safe.
as with a certified QC power supply.
The higher voltage is there to compensate for possible power loss and power inefficiencies in different points
of the system (cable length, etc…).
I have actually verified this with the new LG G4, and observed that with a proper QC-enabled adapter, it charges
about 23% faster than with a non-QC 2.1A power supply. Depending on the phone, your luck may vary.
Incidentally, small details such as cable quality (I’m serious), cable length and other factors that could create
power-loss from the power supply to the phone could affect charging speed. Here’s what you need to get
quick charge working:
§ A Q.C certified adapter
§ A decent cable (copper/metal diameter). I have seen flimsy cables that would not allow fast-charge
§ A C compatible phone. Check the specifications or the Qualcomm Q.C list
Common questions:
§ Are Q.C adapters from different manufacturers compatible? Yes
§ How do I know if my charger is Q.C: check for a Q.C logo
How to measure it?
It is common to read things like QC should charge a phone by 60% in 30mn or something of that kind.
This is a good way to show the faster charging on any given phone, but this is not great to compare
phones with different battery capacities.
We prefer to use “mAh per minute”, which better describes how many units of energy are being stored
for every minute of charge. While it is not a strict energy storage unit, it’s clear enough to compare
charge speed between devices of a similar category, like phones. See what is mAh.
Also, note that while charging speed is relatively stable from 0% to 70%, it gets progressively slower.
For instance, it takes considerably more time to go from 90% to 100% than from 0% to 10%.
mAh/mn is simple: if your phone has a 3000 mAh battery, and it charges by 50% in 30mn, it means that
1500 mAh worth of energy has been accumulated in 30mn, which is 50 mAh per minute.
The chart above shows a small sample of charge speed from popular smartphones. The top speed that
we have seen so far is 50 mAh/mn of charge. That’s true for some Q.C phones, but not all. Phones using
other sort of fast-charging technology also top at 50 mAh/mn, like the Galaxy S6.
Conclusion
Quick Charge addresses an essential need to extend or improve the battery life as conveniently as
possible.
Being able to gain a significant charge in a relatively short time can make all the difference in the world.
However, until OEMs make it easy for users to see (on the screen) if a fast-charging is underway or not, some confusion will remain. Some communications efforts are underway,
and this protocol is bound to expand, so in the near future the odds to have a happy match between
phone
and charger should be much higher. In the meantime, you need to pay a bit more attention.
Happy charging!
