Mini power bank (based on IP5407)

Brief Description:
1. Supports 5V2A output and simultaneous charging and discharging.
2. Supports 4.20V and 4.35V batteries. (Lithium batteries can be connected in parallel, but not in series.)
3. Four LEDs display the battery level, and there is one LED light.
4. Features overcharge, over-discharge, overvoltage, overcurrent, and battery overheat protection.
 
Function Summary:
1. Single-click button to view battery level; long-press button to turn the light on/off.
2. Used for charging.
 
Brief Explanation :
1. H2 on the lower right of the PCB is the positive terminal of the lithium battery, and H1 is the negative terminal. The holes next to H1 and H2 are for passing lithium battery wires.
2. The large hole in the middle left of the PCB allows the R29 thermistor to be close to the battery to monitor battery temperature and prevent the lithium battery from overheating.
3. Two 8205a batteries are used because the maximum source-drain current of a single battery is typically 1.7A or 2A, which is too extreme. Connecting two 820a batteries in parallel to shunt the current ensures that it operates within a safe operating range.
4. Here I used two 18650 2600mA lithium batteries.
 
Notes:
1. The LED I used to display the battery level is 0603, but the actual package is 0805. Both 0603 and 0805 LEDs are compatible.
 
The lithium battery is at the bottom, and the board is on top. I only had hot melt glue on hand, so I glued a bunch of stuff together... If you have regular glue, you can use that for
the outer casing. (STL file uploaded)