Review on Treva Rechargeable Battery Small Fan - Portable Travel Fan with USB Charging, 3 Speeds & Circular Cooling - Handheld/Desktop Size (Grey, 2) by Robert Carter

I bought two of these fans; one from Walgreens and one from Revain. Both work great when new and generate high winds, but after about ten hours of use they can start to rattle a bit. That happened to my two fans. Engines are under-lubricated at the factory and will dry out over time, leading to noise and erratic behavior if you don't take the time to re-lubricate them. Luckily, this is easy to do since the fan is held together with six Phillips screws. withdraw. Now you have access to the engine. Put a drop on the shaft that spins the fan and reassemble. I did this with my oldest fan, which would slow down and speed up on its own like it was sticking, eliminating both the behavior and rattling it was having. The battery life is excellent and far exceeds what is shown on the site. They use 2200mA battery cells instead of 1000mA battery cells as stated on the bottom of the fan and while I haven't timed it I know I always leave the fan on while I'm in bed and it's still running when i wake up the next morning. It's a great fan if you're willing to lube the engine up a bit. Otherwise I'd suggest looking elsewhere if you're not comfortable with that.