- I wanna find out what's the fastest I can charge an iPhone, even if it means getting pretty crazy. This is an iPhone 8 with
a brand-new battery. It charges from empty to
full in around an hour and 57 minutes using the
fastest charger that I have. So I wanna see what I can
do to speed things up a lot. I'm using an iPhone 8 because
it was the first iPhone with fast charge, and I'm planning on breaking a whole lot
of phones in this video, so I didn't wanna spend the
big bucks on the latest iPhone. The first obvious thing to do is to just add more chargers, inspired by our friend TechRax. This is 100 chargers, and this is 100 cables. And while I don't think
this will work very well, I gotta try it out. (exciting electronic music) (exciting electronic music continues) Man, who thought stripping this many wires would be this hard work? (exciting electronic music continues) Okay, let's give this a shot. There we go. It's turning on. Hey, hey! It's charging. Here we go.
(air whooshing) There we go. That wasn't any faster. (chuckling) In fact, it was a lot slower. But according to the math, since each one of these
chargers can supply one amp, I should be able to charge this 1821-milliamp-hour battery in the iPhone in a little over a minute. So what's preventing that? So I grabbed a second phone
that's currently discharged, and I'm gonna hook it up to
my benchtop power supply. Shout out to Keysight for hooking me up with some cool test gear here. Five volts. Yes. And then it's already set to 10 amps, which is the max for this circuit. And it's charging. Okay, cool. We are currently drawing almost one amp, but you'll notice we're
not drawing 10 amps. So why, if the power
supply can supply 10 amps, why is this only drawing 9.6? To show you why, I'm gonna
have to take apart the phone. (slick electronic music) (slick electronic music continues) (slick electronic music continues) All right, there is the battery. Now, let's take this apart. (thoughtful music) There we go. So this part here is
the actual battery cell. This is where the chemistry
magic is happening to store the electricity. But this part up here, you can see there are
all these little chips. This is called the BMS, and this is the battery management system, and it's responsible for
a couple different things, making sure that the battery
doesn't get overcharged or undercharged or overheat. It also has something
called the gas gauge, which keeps track of how
much electricity goes in and out of the battery cell, which tells you how charged
or discharged the battery is, and it actually talks to the rest of the phone to tell it that. The BMS is actually limiting
that charge current. I think the next step is to
figure out how to bypass this. So on the back side here, these are where the
tabs get spot welded on. I wanna solder on a wire
to each of these sides, and I'm gonna run the risk
of overheating the battery, but it should be okay. I've done this before. We're gonna use some
eight-gauge wire here. Let's pre-tin this thing. Gonna kinda tin this up flat. Let me grab a piece of cardboard. (thoughtful music) That'll work. That'll work. I'm gonna
leave this right where it is. But now we have two charging
wires that bypass the BMS. Tomorrow when it's light out, I'm gonna take this outside and try and charge it at a much higher amperage than the BMS would normally allow us to. This is a 90-amp four-volt power supply. It's variable between
about 3.5 and 4.4 volts. I set it to 4.2, which
is about the maximum this battery should be charged at. 4.174. Good enough. Needless to say, if it's not obvious, don't try this at home. (airy music) I'm gonna go get a current meter here. Five amps. It doesn't seem
like it's volting at all. A little warm, but not much. It's, like, skin temperature at best. Well, it's only charging at 1.5 amps. It's really not much more
than a normal charger. I'm gonna stop it once
it gets down to one amp, 'cause I don't think we're
gonna see any fireworks here. 0.98. I might call it here. Take this off. Just being extra careful. I don't just want this
thing to explode on me. I'm not expecting it.
(airy music continues) Put the battery in the bucket of sand, just in case it has thermal runaway later, inside a plastic bag just
so it doesn't short out from moisture in the sand. That did not go the way I expected it to. I expected to have a lithium battery fire. So that's a 1.8-amp-hour battery, which means it should charge at 1.8 amps, would take an hour to charge. You know, we started at maybe four amps and came down past two, so you know, had we kept charging it, I don't know, probably take an hour, hour and a half. But in my opinion, we can still
do a lot better than that. So let's head back inside. I think we're done with
the LiPo batteries, but I have something else to try. These here are lithium-titanate batteries, and they're supposed to be one of the fastest-charging
types of battery chemistry. So I've built a small battery pack out of four of them to
hook up to the iPhone here that I've removed the
standard battery from. Actually, over here. I've removed the stock battery and I took the BMS off of it
and just hooked up two wires to where the cell would normally be. And so this can plug in here. This is a little step-up
voltage regulator. The max voltage of these
lithium-titanate batteries is only 2.85 volts,
whereas a normal LiPo cell in an iPhone is around 4.2, 4.3 volts. This little voltage regulator actually steps up to five volts. The phone seems to
tolerate that just fine. I've got it set to 2.85 volts. This maxes out at 10 amps. These can be charged up to five amps each so they're wired parallel. 20 amps. We're gonna charge it at 10 amps 'cause that's what I've got. Right here. One, two, three, go. All right, charging at 10 amps. Look at that. 26 watts! (laughing) That's awesome. Okay. This is way faster so
far than a stock battery. We can plug in the phone now. So you can see the phone is
reporting it's at 100% charge. It's not at 100% charge. It's just that the BMS
has no idea what this is and what voltage it should be at, and BMS is pretty useless right now, which is what regulates
the phone's knowledge of how charged it is. We're gonna go off of how
much current is flowing into the battery for how charged this is. Once it hits about 150 milliamps, that's kinda what a stock battery
will do when it hits 100%. I'm gonna let this run for a little bit. I'll be back with you shortly. (air whooshing) Okay, it's been around 21 minutes, and we're getting very
close to 150 milliamps, which is what I said the cutoff would be for considering this fully charged. (air whooshing) There we go. Let's call it 22 minutes to fully charged. That is not bad, to go from empty to full on an iPhone in 22 minutes. But can we do even better? What if we don't use a battery at all? This is a supercapacitor. It can hold a little bit more
than a normal iPhone battery, but it can also charge super
quickly like a capacitor, and this one is a 5000-farad
lithium-carbon supercapacitor that has a max charge current
of 47 amps, which is insane. Remember, this charger is only one amp, so to charge it at 47 amps, I
need something much beefier. This charger is 90 amps, and I've hooked it up with two-gauge wire and these beefy 175-amp connectors. So let's give this a shot. Here we go. Okay, I think that's it. Yeah, we're pretty much
at 4.2 volts on here and nine minutes. I think I'll declare that. Good. Wow, nine minutes. That's crazy. That's 13 times faster
than the stock iPhone. Now, obviously this is a bit bigger than your standard iPhone. One of the downsides is that supercapacitors
are a lot less dense in terms of energy storage, so to store the same
amount of charge as a LiPo, they need to be physically bigger, or to put it at a different
way, a supercapacitor that was this size would store
about half as much energy. So would you rather have
an iPhone that could charge in nine minutes but would
only last half as long, or how about an iPhone that
would charge super fast, last just as long, but was twice as big? Ultimately, a lot of these product and engineering decisions
come down to trade-offs. I'll be honest, going into
this, some of the physics and chemistry involved
was a bit over my head. It's not uncommon for me to need to learn something new
for one of my videos. I'm always learning as I go. So are all the best engineers
and creators that I know. And categorically, they all learn best by diving in and trying to solve problems and come up with creative solutions. They don't just read a
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