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Xiaomi's '100W' Quick Charging Goes From 0 To 100 In 17 Minutes (arstechnica.com)
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.
Whether that's time to discharge or time to replacement is left to the imagination of the reader.
they could be using multiple smaller bateries, each with its own controller. and charge them in parallel
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?
Do they have any info on what that does to the life of the battery, as well as any potential fire hazards? Ah - just read the article - no they don't. No laws of physics have been violated. This will be harmful to the battery, and I would want to charge this in a Bat Safe.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
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 back to what you need, 3V to 4.2V DC. Which physically isn't very big with a high switching frequency, but it's still going to dissipate some heat and realistically that is your practical limit. It can be (probably is in the product demoed by TFA) helped by using exotic semi conductors for the switch like GaAs. Not normally worth the $1 or so the part would cost, but for a high end phone where thermal issues are key... that $1 buys you a feature the other guys don't have. A feature you didn't need but never mind that.
So does it shorten your battery? Not the charge rate, really. It's nothing to write home about, but the whole package is gonna get hot. I have a OnePlus which has some proprietary fast charging and it gets pretty toasty here in the tropics. So much so, I just use a regular charger. Lithium cells do degrade with elevated temperatures.
Frankly with USB-C, I think wireless charging and super fast charging etc are all daft. It's super easy to plug in, and a couple of amps is already catered for in the spec. What is the goddamn hurry? This is basically like wireless charging, a solution in search of a problem.
Going from 0W to 100W in 17 minutes is an awfully long time.
Sure, it charges fast. What is the magnitude of effect on the battery's usable lifetime, if any? Is the battery replaceable? (lol, as if)
You can charge a phone that quickly, as long as it's in a freezer. 100 watts is a good deal of heat, and has to go somewhere. Getting it to charge that way at room temperature is a much larger challenge.
Bruce Perens.
Just don't charge them near me or anything I own, thx.
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.
world was created 5 seconds before this post as it is.
It also severely shortens your battery lifespan. In fact the higher the charging voltage, the shorter the lifespan.
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 charge at 4A max.
Meaning it would take 1 hour to charge them fully.
You would think that two 2000mAh batteries will charge faster in parallel, except they won't.
They are smaller, so 1C means each needs to be charged at 2A max. So in the end, each needs to be charge to 1 hour again.
If you manage to charge them in parallel, you're simply back to 1 hour again.
Now if you paid attention to the introduction you see a completely different way to improve things :
charge cycle depth.
As I said, 1C isn't actually constant on a Lithium battery (Again, DON'T ACTUAlLY TRY CHARGING AT 1C AT HOME).
If you don't go all the way up to the max (and symetrically, don't completely discharge your battery and start all the way down from the beginning - though nearly no electronics does that, because this REALLY kills the battery and require extreme careful charging on the lower part), you can avoid the parts of the charge cycle that are extremely slow, and keep in the sweet spot where the charging rate is higher.
e.g.: the 4000mAh battery is what other would have called a 6000mAh battery.
Or another way to put it, Xiaomi's charge cycle only goes from 15% to 85%.
(Thank fully, the popular trend of ever larger screens gives more room for larger battery space, thus helping making this easier.
Well, that's unless the manufacturer have jumped onto the "making the phone thin enough to slice cheese" bandwagon)
That's also how Telsa can manage that much charge of battery in such short time: they don't push the battery too much.
And if you paid attention about my above comment about "REALLY killing" the battery, you'll deduce that shallower charge cycles (e.g.: always charge between 15% and 85% only) will lead to also much longer battery life.
Which is also another reason why Tesla is doing it: their car batteries are supposed to last for 8 years, not be thrown away after 2 years like most smartphones are expected to be in today's over-consumerist societies.
(And on these cars, you can even further configure even shallower cycles on the onboard controller to extend battery life even further).
Different chemistries might help having better life endurance and faster cycles.
This is what is done by most remplacement of lead-acid batteries (LiFePo can charge at a faster rate, have more safety and longer life, but at the cost of less energy density. - But here: who cares? you're replacing a giant, heavy, low density lead-acid battery. Even LiFePo is a ginormous gain in space and weight).
Tesla does it too (their batteries are a different tweak of Lithium Nickel Manganese Coblat, than the Lithium Cobalt in your laptop. Which has the bonus advantage of being less reliant on Cobalt and other conflict minerals)
TL;DR:
- No parallel charging doesn't make it fast.
- Charge cycles depth, and tweaking chemistry is what can shorten charge time.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
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.
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) and a tweaked chemistry in the battery, and is possible to imaging a battery that can charge at 3C without dying within a couple of months (or exploding within a couple of days)
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
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)
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
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.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
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.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
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.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
>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).
I should use this sig to advertise my book ISBN-13 : 978-1501515132.