Galaxy Note9: S Pen Charging method and Usage time

To supply power to the Bluetooth module, a Super Capacitor has been integrated into the S Pen instead of a battery.

ㆍ Charging method: The S Pen begins charging wirelessly once it's inserted into the device.  It only takes about 40 seconds to fully charge the S Pen.

Super Capacitor:

ㆍIt may not charge the S Pen as much as a lithium-ion battery does (i.e., the typical battery used in Smartphone’s), but the charging time is very short. 

ㆍIt's suitable for the S Pen, since the S Pen is inserted and pulled out frequently, and also typically used for a relatively short amount of time once pulled out.

ㆍA lithium-ion battery uses chemical reactions whereas a super capacitor uses the physical characteristics of electrons for charging.

ㆍUsage time:  When fully charged, its standby time is 30 minutes, and its button can be used 200 times.  Even when the S Pen is discharged, all of its features, including Writing/Drawing and Air Command, can still be used.

Wireless Charging:

ㆍThe way wireless charging works is by creating a magnetic field between the coil inside the device and the coil inside the S Pen. Note that S Pen must be inserted correctly and completely.

ㆍWhen the S Pen is fully charged, the device's battery loses 0.5 mAh, which is extremely insignificant. Moreover, since their charging methods differ, it's impossible to charge the S Pen using the device's wireless charger.