Xiaomi's '100W' Quick Charging Goes From 0 To 100 In 17 Minutes (arstechnica.com) 67
Xiaomi is teasing a new 100W quick-charging solution for mobile phones that can fully charge a large 4,000mAh battery in just 17 minutes. Ars Technica reports: The video shows a charging race between two phones, Xiaomi's unnamed "100W" prototype and a phone with "50W" charging from "Brand O," which looks like it's an Oppo RX17 Pro. I put both of these wattage ratings in quotations because neither phone actually hits its rated charging speed. Xiaomi's video shows a live, in-line power reading, and the "100W" charging shows a sustained ~80W (18V / 4.5A) from about 5-30 percent, with a peak of 88W. The competing 50W Oppo quick-charge solution caps out at around 40W.
Branding aside, what matters is the actual charging speed, and Xiaomi's ability to fully charge a phone battery in 17 minutes is impressive. The test stops when the Xiaomi phone fills up, leaving the Oppo battery stuck at a mere 65 percent. Considering that Xiaomi was charging a 4000mAh battery and that Oppo only had a 3700mAh battery, Xiaomi's solution is about 1.6 times faster than Oppo's quick charge, which is currently the fastest charging scheme on the market. Unfortunately, Xiaomi didn't offer any specifics on how its charging solution works.
Branding aside, what matters is the actual charging speed, and Xiaomi's ability to fully charge a phone battery in 17 minutes is impressive. The test stops when the Xiaomi phone fills up, leaving the Oppo battery stuck at a mere 65 percent. Considering that Xiaomi was charging a 4000mAh battery and that Oppo only had a 3700mAh battery, Xiaomi's solution is about 1.6 times faster than Oppo's quick charge, which is currently the fastest charging scheme on the market. Unfortunately, Xiaomi didn't offer any specifics on how its charging solution works.
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it's just two batteries.
think about it. sometimes the obvious solutions are the correct ones.
how much overall battery volume does each phone have inside it?
and that chargers like a laptop charger anyways.
NO parallel charging. (Score:3)
it's just two batteries.
Nope.
Won't work.
Charging rate is expressed as a fraction of the battery capacities ("C").
Meaning that two smaller batteries, will also each charge at half the maximum rate.
So if you manage to charge them in parallel, you're back at the initial charge time.
Instead you need to tweak the chemistry and shallower charge cycles.
With an expected battery life of 3 days (Score:3)
Whether that's time to discharge or time to replacement is left to the imagination of the reader.
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From 0 to 100, where 100 is fire.
Re: With an expected battery life of 3 days (Score:5, Informative)
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It's almost as if you don't think anything can ever be improved.
Shallower cycles (Score:2)
Indeed! If charging Lipo batteries for RC cars has taught me anything, itâ(TM)s that the quicker to 100% charge, the quicker the battery is permanently toast.
That's mostly true when going to 0% to 100% charge.
If cycling only through the 15% to 85% part of the battery you could actually charge faster, and that can also simulteanously extend battery life.
i.e.: if their 4000mAh battery is what other manufacturer would have called a 6000mAh battery.
(Made easier by the current trend of having giant screens, thus giant phones and therefor a little bit more space for batteries)
multiple smaller batteries (Score:3, Interesting)
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Possible but the xtra controllers will either take up more space which means the phone has to be bigger and costlier to manufacturer or the battery capacity is reduced to compensate.
Says who? A battery charge IC can be the size of a grain of rice these days.
Parallel : Doesn't change a thing ; Charge cycle d (Score:2)
Charge rate limitation is expressed as "C" - i.e.: in multiples of battery capacity.
Let's say LiPo is roughly 1C.
(It's a very rough approximation, DO NOT TRY THIS AT HOME.
Actual Lithium charge rate limit depends on current voltage. When nearing full capacity, the max charge current should decrease. Basically, beyond a certain point, you charge at constant voltage (which gives decreasing current) instead of at a constant current (which forces you to keep at a fixed voltage delta) )
A big 4000mAh battery would
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>As I said, 1C isn't actually constant on a Lithium battery (Again, DON'T ACTUAlLY TRY CHARGING AT 1C AT HOME).
Why not? When the data sheet specifically gives you the places in the CCCV curve that you can charge at 1C (1.2C in the case of the cells that I do charge at home).
Effect on batteries? (Score:2)
This sounds like it'd be a bit hard on the batteries themselves, like as in, shorten their usable life.
Possibly increased risk of catastrophic failures?
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You mean they might explode? A product, in China, exploding? Inconceivable!
Charge cycle depth (Score:2)
This sounds like it'd be a bit hard on the batteries themselves, like as in, shorten their usable life.
Unless its achieved by decreasing the depth of the charge cycle.
i.e.: their 4000mAh battery is what another manufacturer would have called a 6000mAh battery.
Shallower cycle would help extending the battery life.
Shallower cycle would keep the charging in the part of the cycle where the battery charges at max current (as opposed to "tappering" into max voltage, decreasing current closer to the ends of deeper charge cycles).
Combine with a giant screen (thus more room in the body for a physically larger battery
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So does my Think Pad, and it is annoying.
I went to upgrade my RAM, and I am old school and like a device fully powered off before I do such a hardware upgrade. Only to find there was still power from that battery.
New computers rarely have a hard power cutoff switch, and pressing the power button is controlled by the OS and the Firmware, both being programmable logic. They sometime may fail. In case of a major OS problem, unplugging the system and taking the battery out isn't enough.
I wonder (Score:5, Interesting)
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life of the battery won't matter when the whole thing will blow up the fifth time you use it, and take your house or car or office with.
I recently made a safety video for an RC plane club. There are two main catastrophic failure modes. The first is shock damage. This is mostly a lot of smoke. Not much fun, but you'll probably not be harmed - well badly harmed depending where you are and where the battery is
The second is drastic overcharging. This is the one that makes a lot of fire. I saw a demo of a RC 3S 11.1 Volt LiPo being charged as if it was a lead acid battery, and charged as if was a 20 something volt version. Holy crap! But hey,
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I keep some slow chargers around for overnight use, to preserve the battery.
I was thinking about an open source project to build a smart charger that linked to the phone via Bluetooth or over the USB cable. The phone would be able to control the charge rate, and an app would offer features like adjusting charging speed based on the time and only charging to 80%.
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Yeah, but for phones, i.e. USB power output... Actually something like link but open source would be nice too.
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I keep some slow chargers around for overnight use, to preserve the battery.
Smart move. A LiPo can last a surprising long time when not abused.
I was thinking about an open source project to build a smart charger that linked to the phone via Bluetooth or over the USB cable. The phone would be able to control the charge rate, and an app would offer features like adjusting charging speed based on the time and only charging to 80%.
I know some RC airplane enthusiasts that would go for an outboard version of that.
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Unfortunately USB phone charging and battery charging for RC are rather different problems.
With USB you have to pretend to be lots of different types of charger and implement current limiting, and the adjustments you make are not very fine gained. The actual battery charging is handled by the phone, all you can do is supply 5V at a certain max current.
Direct battery charging is actually easier in many ways, just a constant current circuit with digital adjustment and some monitoring. One of the nice things a
Re: (Score:2)
Unfortunately USB phone charging and battery charging for RC are rather different problems.
With USB you have to pretend to be lots of different types of charger and implement current limiting, and the adjustments you make are not very fine gained. The actual battery charging is handled by the phone, all you can do is supply 5V at a certain max current.
Direct battery charging is actually easier in many ways, just a constant current circuit with digital adjustment and some monitoring. One of the nice things about Lipo is that it's really easy to charge, compared to say NiMH.
I have a battery charger that is designed to charge LiFe, LiPo, Lead Acid, NiCad and NiMH. It has a lot of different cables to attach to various devices, and is programmable for different charge currents and rates and of course types. It's pretty cool, but the big trick is making certain you program it to the right type of battery. I definitely could make a real mess if I don't program it correctly.
I do charge my battery packs at about half the current that I could.
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you could even give it a fancy, Chinese name. I suggest "Qi"
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I just remember the old hot rods with oversized engines that they had to cut out the hood, to fit the engine block, often removing the exhaust system, so out of the engine we seem combusted flames going out the sides. We just need phones with exposed heat sinks for added effect we can put a spot that you fill with water to watch steam expelling from it, or a closed pipe system with clear tubes so we can see colored fluid moving about, like on the old Cray super computers.
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I just remember the old hot rods with oversized engines that they had to cut out the hood, to fit the engine block, often removing the exhaust system, so out of the engine we seem combusted flames going out the sides. We just need phones with exposed heat sinks for added effect we can put a spot that you fill with water to watch steam expelling from it, or a closed pipe system with clear tubes so we can see colored fluid moving about, like on the old Cray super computers.
Well played! I like the idea!
No impediment to this but why?! (Score:2)
They are charging the cell at a little over 1C. This is really pretty trivial for modern lithium cells. The problem for mobile devices stems from two things --- power cables that were ostensibly designed for data, and the necessity to put the power circuitry in an already compact box, right next to the battery, and a computer.
A solution to the first problem is to up the voltage on the cable, which is what most of these fast charge standards do. However you *then* require a buck regulator to get that voltage
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Wireless charging is a convenience, hugely so for my crippled hands but one my able bodied friends enjoy as well.
Any modern home is full of conveniences we use without extra thought, no need to scoff at one in particular if people enjoy it.
As for quick charging; people seem to have their phones surgically attached to their hand and need to recharge by mid afternoon. I don't and personally prefer to keep the battery cool and charge overnight but to each their own.
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> They are charging the cell at a little over 1C. This is really pretty trivial
18 V x 4.5 A is converted to about 20 A at 4 V. For a 4 Ah battery; that is 5 C/h of charging current. I wouldn't call that trivial.
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You don't even need to do any fancy calculations with volts and amps, according to TFA it takes 17 minutes to charge hence it's charging on average at about 4C.
Which is indeed quite high, and while pushing this over USB PD shouldn't be a problem, I'm really curious what the long-term implications are for the battery.
Should have picked a faster capacitor... (Score:1)
Endurance (Score:2)
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It can't be good. After all, if it didn't have problems, companies like Tesla and other EV companies would be hopping at the chance to fully charge their cars in under 20 minutes. And these are vehicles with closed loop cooling systems and everything so they're able to dissipate the heat.
Sure you can (Score:2)
Yeah... flaming Chinese batteries (Score:3)
Just don't charge them near me or anything I own, thx.
Great! (Score:2)
Very rough math (and heat) (Score:4, Informative)
Assuming it is a Li-ion battery- 3.6V nominal and 4Ah there was 14 Wh stored in the battery. The charger used about 80W over the time 17/60th of an hour- about 23 Wh provided- so 9Wh ends up as heat, using a conversion- that means about 32000 J.
To put this in perspective- 12oz of water is about 340g, and the specific heat of water is 4200 Joules per kilogram per degree Celsius (J/kgC) so... 32000 J /(.340 kg * 4200 J/kgC) = 22C (72F) - not an insignificant amount of heat. Not crazy though.
Focus is on wrong thing (Score:2)
I'd rather, at this point, they work on a better connector that can take 10,000 connect cycles, and, even more importantly, bumps and yanks at angles on the cord while connected.
That's much more important than lopping another 15 minutes off charge speed.