The Galaxy Note 9 S Pen has a clever rapid-charging "battery" with one tiny flaw

The Galaxy Note 9 S Pen has a clever rapid-charging "battery" with one tiny flaw
So, the Samsung Galaxy Note 9 is now official, and along with it comes a brand new S Pen – an S Pen that stands out with more than just its bright yellow paintjob. Samsung's newest stylus is more functional than ever, enabling cool tricks like activating the camera shutter or switching between PowerPoint slides from afar at the press of a button. This is made possible by the inclusion of Bluetooth connectivity, allowing the new S Pen to communicate wirelessly with the Samsung Galaxy Note 9 even from a distance of several feet. Neat, huh?

When I learned this, I initially assumed that Samsung had equipped the S Pen with a teeny tiny battery. It had to have one, since a power supply of some kind is mandatory to allow the S Pen's Bluetooth radio – or any Bluetooth device, for that matter – to work. But I was wrong, and a just-published infographic revealed that Samsung has chosen a different route for powering its stylus. It turns out that instead of a battery, inside the Samsung Galaxy Note 9 S Pen is a component known as a supercapacitor. 

What is a supercapacitor? What is it doing inside the S Pen?

Not long ago, I wrote an article explaining supercapacitors along with their pros and cons, so there's no need to go into much detail here. All you need to know is that they store energy, much like batteries, only differently. And in theory, a supercap seems like a much better fit for the S Pen than a traditional battery for a number of reasons. Although... it may have one huge disadvantage as well. Let us go through them.

  • Supercapacitors do not degrade as quickly as batteries do. Lithium batteries – the kind used in practically all phones, tablets, and laptops nowadays – gradually lose capacity as they age due to the chemical processes going on inside of them. Every charge-discharge cycle shortens its lifespan. It is not uncommon to observe a noticeable drop in a smartphone's battery life after a couple of years of use. A supercapacitor, on the other hand, can last a decade if it is used properly, which is great as I'm sure an S Pen battery replacement service wouldn't have been cheap or easy to perform.
  • A supercapacitor won't mind staying fully charged all day. Another way of killing a lithium battery faster is to leave it empty or to keep it at full charge for a long time. If treated like this, they tend to swell and cause all sorts of trouble. In contrast, having a supercapacitor fully charged for months will have very little (if any) impact on its longevity – perfect when a Note 9 S Pen would be fully charged 99% of the time.
  • Supercapacitors charge rapidly. Lithium batteries are tricky to charge. They require specialized circuitry and go through several charging stages before they reach a fully charged state. Supercapacitors can be charged literally tens and hundreds of times faster, which is probably why the Note 9's S Pen charges fully in 40 seconds.

But supercaps have a major disadvantage

There's this one caveat that has to be mentioned. While supercapacitors are pretty neat, they hold much less energy than typical batteries – over a thousand times less per unit of volume. As a result, the Note 9's S Pen last just 30 minutes per charge, even with the minuscule power requirements of Bluetooth LE technology. To be clear, you'll still be able to take notes even when the S Pen is out of juice, but you won't be able to use any features that rely on Bluetooth connectivity to work. 

On the bright side of things, knowing that the supercapacitor in the S Pen is a tiny one, I'm sure that its impact on the Galaxy Note 9's battery life would be negligible, if not impossible to measure or detect. Keep in mind that the S Pen draws power from the Note 9 while it is resting in its silo.  

Learn more about the Galaxy Note 9:

Related phones

Galaxy Note 9
  • Display 6.4 inches
    2960 x 1440 pixels
  • Camera 12 MP (Dual camera)
    8 MP front
  • Hardware Qualcomm Snapdragon 845, 6GB RAM
  • Storage 128GB, microSDXC
  • Battery 4000 mAh
  • OS Android 10
    Samsung One UI



16. Valdomero

Posts: 708; Member since: Nov 13, 2012

The only flaw I see in that pen is that i doesn't have a second button, or a programmable button, the recharge time of 40s is a blessing actually.

15. BullaBoss

Posts: 141; Member since: Jul 17, 2018

I think you should point out a flaw of supercapacitors in general.

14. power21

Posts: 80; Member since: Jul 15, 2015

I just want the pen to write. I don't care about those other useless features, but I would be impress if the pen can transform into a bird and spy on autobots or transform into a gun.

13. fyah_king unregistered


12. Azonx8472

Posts: 30; Member since: Apr 13, 2013

Since when does something that needs to be charged for 40 seconds is a flaw?

11. Man_Utd

Posts: 190; Member since: Feb 03, 2015

I like the implementation. We need companies to keep pushing and bring new tech. Waiting less than one minute for a consist 30 min life, that's pretty nice IMHO.

8. Daftama

Posts: 641; Member since: Nov 03, 2012

You should be banned this article should be banned. Really out of all the things to complain was this....could've said the color, size, don't have premium tip, permanent tip, why they still break, it doesn't have a mic. I can't gap locate my missing pen, maybe why can I use tip as a camera or why million of other things just like I don't make sense it's exactly how this article is

6. Rampage_Taco

Posts: 1128; Member since: Jan 17, 2017

We all know the only flaw the S-pen has in PA's eyes is the fact that it's Samsung exclusive

5. TreyTreyTaylor

Posts: 728; Member since: Dec 21, 2010

I'm thru with PA. If something takes one minute to charge, theoretically it doesn't even need to be charged.

3. hurrycanger

Posts: 1777; Member since: Dec 01, 2013

Flaw? What flaw? The damn thing can still take notes without juice! Are you leaving the pen outside continuously for 30 minutes to control bluetooth? What a joke.

2. RoboticEngi

Posts: 1251; Member since: Dec 03, 2014

OMFG......did you read the charge time? 40 secs......and still you cry like babies...........

1. Critical54

Posts: 36; Member since: May 04, 2016

This makes no sense, Did you not see in the conference that charging time takes only 1 minute? Even if the charge lasts 30min, It takes one to charge it.......

10. Finalflash

Posts: 4063; Member since: Jul 23, 2013

It's the stupidest gripe, at worst it turns into the normal S-pen. Basically, you charge it for the advanced features, otherwise it works as a pen all the time. But this is the kind of crap authoring you can expect from iPA now, and that from their senior editor. In the end, this ain't no Apple pencil charging, I bet iPA had nothing to bad to say about that.

* Some comments have been hidden, because they don't meet the discussions rules.

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