https://youtu.be/SH9DnOuA2XQ
9V rechargeable batteries aren't as common as AA/AAA ones so I looked on AliExpress for some. I bought a pair of them to use in my multimeter and stud finder. They are recharged via USB-C which is handy. The question is, do these actually have 12,800 mAh of capacity? (LOL)
9V Lithium Battery 12800Mah Large Capacity Type-C Fast Charge Red and White Two-Color High-Value Outdoor Emergency/Remote Control Toys/Drone/Camera/Microphone Universal Safe and Durable Hot Model Best-Selling: https://s.click.aliexpress.com/e/_ooDOpPQ