Best answer: The Surface Slim Pen gets an estimated 15 hours of battery life, but you won’t have to worry about that much thanks to its convenient charging options.
Slimming it down
The Surface Slim Pen is a redesigned stylus that works with Surface devices. It rolled out alongside the Surface Pro X, but it also works with the majority of the Surface line, including all Surface Book devices, all Surface Laptops, the Surface Go, all Surface Studio devices, and every Surface Pro since the Surface Pro 3.
The Surface Slim Pen features a flatter design than previous Surface Pens. Many compare it to a carpenter’s pencil with its relatively flat body, though it has smooth and rounded sides. According to Microsoft support, the Surface Slim Pen gets an estimated battery life of 15 hours, though you shouldn’t have to worry about its battery often thanks to its convenient charging options.
Charge it up
The Microsoft Surface Slim Pen doesn’t require batteries, instead it can be charged wirelessly. It comes with a charging cradle or you can charge it inside the Surface Pro Signature Keyboard. Unfortunately, the only way to get the Signature Keyboard is to purchase the Surface Pro X Signature Keyboard with Slim Pen Bundle, which includes the Slim Pen and the Surface Pro X Signature Keyboard.
The Surface Pro X Signature Keyboard is the most convenient way to keep the Surface Slim Pen charged. You can pop the pen into the keyboard and keep the pen charged while you’re on the go. A handy feature of the Signature Keyboard is that it makes sure your pen is always upright and ready to charge. It uses magnets to flip the Slim Pen over if you try to rest it inside the keyboard incorrectly.
If you don’t want to purchase the Surface Pro Signature Keyboard or if you plan to use the Slim Pen with a different Surface device, you can charge the pen wirelessly inside the included charging cradle.
New design, same functionality
The Surface Slim Pen is totally redesigned, offering a slimmer profile and wireless charging to complement the Surface Pro X and a wide variety of other Surface devices.