Review on 🔋 Smart Universal 4-Bay 18650 Battery Charger for Rechargeable Li-ion Batteries and USB Charging Port - Compatible with 10440, 14500, 16340, 18650, 26650, 18500, 17670 (Batteries Not Included) by Danielle Hartman

Somehow I misunderstood that this charger also comes with an AC plug. This is not the case and the only power source is the USB cable. Fortunately, I have already bought 3 packs of USB charging adapters. Works perfectly! I ripped apart a "dead" laptop battery only to find that I had 8 perfectly healthy 18650 cells inside. It only took a few hours to charge all of them, 4 at a time, and now they're all measuring 4.0-4.2V.