It seems like every few months a new company comes out with a new, fastest ever charging smartphone. Years ago, the flagship iPhone was charging at five watts, and that was fairly standard. It would take about two-and-half hours to charge the phone from zero to 100. Then when the Pixel 1 came out, that was super fast, charging at 18 watts. Then soon the iPhone bumped up to 20. Then you might remember OnePlus beat out everybody for a couple years with 30 watts.
Soon we had 45, 65, 80. Now, today, Xiaomi 12 Pro ships with 120 watt charger. You can buy this right now, today. It charges the whole phone from 0 to 100 in 17 minutes.
And then just a few weeks ago, OPPO demoed a smartphone. It’s not on a real smartphone yet, but it would charge a theoretical 240 watts, which would go from zero to 100 in nine minutes. That’s pretty ridiculous.
As you may have noticed, like I have, pretty much anytime one of these demos gets posted somewhere, universally the comments across the world are, “I don’t want that on my phone. That definitely is gonna overheat. Good luck plugging that in for more than five minutes before it explodes.”
People across the world are convinced that there is no way that this can be good for your smartphone’s battery. Which got me thinking, if this is true, then why would these companies keep doing this? Is fast charging actually ruining your battery?
How Charging Works?
So I dove into it, I just dove straight in. Plenty of Google searches, plenty of articles read, plenty of people talked to, and plenty of hot takes out there, but this is what I found.
Batteries have improved in their chemistry over time, but right now all phones use lithium ion or lithium polymer batteries. And the way they work is they have a positive side and a negative side.
And the lithium ions flow from the negative to the positive side through a liquid electrolyte solution. And as they flow, energy is released into the circuit. That’s what’s keeping the phone powered by the battery.
When that flow is over, though, the battery has reached 0% and is dead. So charging the battery back up is moving those ions back through from the positive to the negative side through that electrolyte solution.
The first thing to know about charging a battery is batteries are kind of like a sponge. They absorb the most energy when they have the least in them. As they get closer and closer to full, they can’t absorb quite as efficiently and then there is some excess lost. With a sponge, it’s just extra water passing through. With a battery, that’s just excess heat. And so what that looks like is charging actually happens on a curve.
Rate Of Charging
Those numbers that you keep seeing with the 100 watts and 150 watt fast charging, that’s not the constant rate of charging. That’s just the peak, the maximum that they’re capable of. That’s typically only briefly the actual rate.
So a 65 watt fast charger, for example, will typically only hit 65 watts for the first few minutes, pretty early on in the charge from low battery, and then taper off and basically only trickle charge at a lower wattage after around 80%.
And you can actually view that if you get one of these incredibly nerdy
cables with the display on it. It lets you see exactly how much power your phone is accepting while you’re charging.
But then the second thing to know is batteries do degrade over time. The iPhone, as you’ve probably seen, lets you literally visualize it. It shows you the percentage. So if you go to settings and battery and battery health, you can see your iPhone’s degradation rating as a number from one to 100.
There are several things that degrade batteries. I mean these are picky little things. They’re very energy dense little storage units. They don’t like being at 100% exactly. They don’t like being at 0%. And they do naturally degrade over time as they go through charge cycles.
And the ions pass through that electrolyte solution over and over again, slowly breaking it down. This is totally natural and can’t really be avoided as you charge the phone more and more.
Heat Is No Good
But the number one factor that damages batteries, that degrades them faster than normal, what ruins your battery is heat.
The ions are moving through that electrolyte a lot, but you can think of the electrolyte basically like salts. They can be pretty sensitive to changes in heat. They can actually crystallize and clog up the anodes and cathodes, which stops them from being able to store the lithium ions.
And like I mentioned earlier, when the battery isn’t in the optimal state of charge, it’s less efficient, and that extra runoff energy manifests as heat, and heat is no good.
So clearly the goal here is to minimize any excess heat around that battery, which would damage it faster than normal. Now the thing is, generally the more wattage, the more power you’re pumping into this battery. The more heat it’s going to generate.
So it sounds like this extra fast charging is clearly bad for your phone. It’s more heat generated and it’s bad degradation. But that’s not something these companies aren’t thinking about.
Heat Management Strategies
Over the years, bunch of these different smartphone companies have basically been working on trying to figure out how to charge these phones as fast as possible without generating any extra heat. If you look just Xiaomi’s page for their fast charging alone, there is tons of charts and graphs and claims about what they’re doing to get around this.
One new advancement came from OnePlus when they dropped that Warp Charge 30T charger. It was kind of interesting and a little confusing maybe that we had Warp Charge 30 and Warp Charge 30T. And both were 30 watts, but 30T was faster. But this was because with 30T, the power management got handled in the brick instead of in the phone. So there was more heat produced by the brick in the wall instead of on the phone near the battery.
So OnePlus could put the same amount of power into the phone but for a longer period of time without heating it up as much. And so the charging curve could be improved like this. So that’s a nice step.
The downside there is now we’re getting larger power bricks, but that’s a bit of a trade off people are willing to make, I guess. But then another way we’ve seen a bunch of companies jump on, especially lately, is with something called parallel charging.
Parallel Charging Explained
Basically, instead of putting a ton of power into a single battery, they actually split up the battery into two cells next to each other. Then add power management hardware to split the incoming power.
This is a simple but brilliant way to get faster charging times without a ton of heat. Imagine, instead of trying to pump 50 watts into a single 5,000 milliampere-hour battery, just doing 25 watts into two batteries of half the size. That’s gonna generate way less heat, it’s only 25 watts, but combined.
When you draw the curves, you can achieve the equivalent of 50 watt charging and you get to put 50 watts on the box but it’s with way less heat. But again, there’s a downside to this method too, which is a slightly smaller overall battery capacity.
Downside Of Parallel Charging
If you take the same internal volume of two batteries instead of one, that means there’s more space taken up by the boundary between the batteries. And the housing and that charging management hardware I mentioned. So you’ll often end up with slightly smaller overall batteries if they’re split like this.
And then of course, something we’ve seen in just about every new phone coming out which doesn’t really have a downside is just adding more cooling hardware onto the phone itself. Sometimes that’s heat shields and vapor chambers. Sometimes it’s a whole fan. But specifically, we’re trying to get the parts inside from getting too hot.
It feels like every cell phone announcement for the past two to three years has some sort of section about cooling, especially gaming phones. You’re, of course, cooling the system on a chip, too, but the better the cooling system overall, the more power you can put into the phone without it getting too hot.
So the real question is, is it working? Is it that simple? As long as you keep the phone cool enough you can put as much power into it as you want? Well, there are the downsides I mentioned earlier with the larger brick and maybe the phone’s gotta be thicker with more cooling.
And has a smaller capacity battery, but the question we’re trying to ask is, what counts as ruining your battery? That’s a simple one, and it turns out there’s actually an industry standard for this.
An Industry Standard
From the research I’ve done and the people at these companies I’ve talked to, the generally accepted target goal is 80% battery health after 800 charges.
So let’s say you charge your phone roughly once a day. That’ll pan out to about two years. So 80% charge after two years. That’s above the industry standard officially not being ruined.
Upcoming Super Fast Charging
Now, for all these super fast chargers that are new. it’s tough, ’cause they’re new. They’ve just come out and we don’t have long-term data. And it sucks that the only information I can use is just coming straight from those companies.
So I’m basically taking their word for it that, yeah, the fast charging doesn’t ruin the phone over time, but it’s the best information we have. it is actually surprisingly impressive.
From their test results, Xiaomi on their site say that their 120 watt charging tech is rated to maintain 80% battery health after 800 charge cycles. Apple on their site, they don’t have the fastest charging, but they say 80% after just 500 charges. But like I said, it seems like they’re outperforming their own claims, under promise, over deliver.
And then OPPO and OnePlus, who’ve announced they’ll have a 150 watt charging phone this year. They’ve specifically stated it’ll go 80% battery health after 1,600 cycles. So that will outperform the industry standard, which I guess means they have room to keep going up.
Now don’t get me wrong, the trade offs are very real. Not everybody wants a thicker phone or a larger power brick or a slightly smaller capacity battery. But from where I’m sitting and from the test results that we can go by, fast charging does not have to ruin your battery life. And really the best part of that is just convenience.
Gallium Nitride Chargers
On top of the fact that these companies are all actively still working on making this stuff better. You might have heard about gallium nitride chargers. There’s a couple actually out there already in the market. That allows the brick to actually be much smaller than the typical silicon chargers we’re all using now. So you can do a 65 watt gallium nitride charger half the size and still put the same power into the phone.
But really what it comes down to these days is, it’s called a smartphone for a reason. Batteries these days are smart. Modern phones all have tons of hardware and sensors inside the phone to help measure temperature and regulate charging. So it’s doing all kinds of stuff automatically. And then the phones all will add a bunch of software features on top to help you actively maintain the battery to the nth degree.
Phones like the ROG Phone 5 have pass-through charging. So when you’re plugged in, and gaming, which is typically not a good idea on a regular phone, it can just power the system and it doesn’t add charge to the battery at all. So you’re not putting extra stress and heat on the battery and it can maintain battery health for a lot longer.
The latest iPhones and Pixels too right now have a feature where if you plug in at night around the same time every night, after a few days it learns when you wake up. So instead of charging right to 100% when you plug it in, it charges up to 80 then waits all the way until you’re about to wake up. Maybe an hour before your alarm, and then charges the rest of the way up to 100 so you wake up with a full battery but better health.
Pretty much any other phone with this super fast charging coming up is gonna have to have a suite of battery health options that you can mess with in the software to take your battery health protection to the next level. So I don’t know how fast these phones charging is gonna get in the next couple years. Inevitably, it’s just gonna keep getting better as the company’s work on it.
What We Can Do
But what I can tell you is the best thing we can do for our phones is to just use them like normal and basically don’t give them any extra reason to get hot. Leaving it in the dash of your car on a sunny day, gaming while plugged in for long periods of time, stuff like that.
If you can avoid your phone getting super hot, you’re doing the best thing you can for your battery. And these smartphone companies all know that battery problems are bad news. So if they’re all doing their jobs, then we should all be good.
The famous Galaxy Note 7 battery exploding issue, as crazy as it was, it wasn’t actually due to fast charging or overheating. It was actually just them with their battery supplier getting some dimensions wrong and some bending going on of the battery with the positive and negative sides up in the corners. Something to think about. Either way, now you have the answer.
Thanks for visiting, catch you guys on the next one.