DIY USB Fan: Battery Indicator & Faster Charging

This article discusses the process of modifying a Smart Frog USB desktop fan to add a battery level indicator and improve charging speed. If you're interested, keep reading!

USB Desktop Fan:

The fan had two main issues:

1.It only had a single 700mA charging chip onboard, and the included 4000mAh battery could be continuously charged.

2.It lacked a battery level indicator.

So, how to modify it?

Choose an IP5506 chip with an integrated boost charging circuit and a 188-segment digital display for the upgrade. The CC pin is used to ensure compatibility with the fan's original two ground buttons. The button section on the original board was slightly modified.

Activation current: 13mA

Static current: Over 30µA, with the total standby current not exceeding 50µA when combined with the original board. It's barely acceptable.

The internal design includes a card slot that fits perfectly. I made a board of this size to match.

I couldn't find any other suitable locations, so I decided to modify the bottom of the fan. Although this slightly impacts the visibility, it's not a major issue, especially since there's no space above the button.

After several rounds of testing, the battery level indicator works well.

Here's the final product.

The small battery is a limitation; at maximum wind speed with oscillation, it lasts for 2 hours. On the lowest wind speed without oscillation, it can run for 12 hours. Fortunately, you can also use it while plugged in via USB, and the chip’s power path doesn’t interfere with charging.