IP2325+ETA3000+S-8252AAL-M6T1U

This system uses a 2-cell 18650 lithium battery charging and discharging management IP2325 (10W) charger, an ETA3000 (active balancing) chip, and an S-8252AAL-M6T1U (battery protection) chip.
The charging power is 10W, with a 5V BUCK boost voltage to 8.4V. The voltage can be changed by configuring the VSET pin of the IP2325. The 0-ohm resistor in this project is a reserved position; the default voltage is 8.4V under no-load conditions and does not need to be soldered during actual soldering. For details, please refer to the attached datasheet.
The ETA3000 chip has a very small package, resulting in significant heat buildup. The balancing current can be changed by configuring the ISET pin, and it can support a maximum current of 2A. It seems that ETA has the ETA3001 with an external MOSFET and the ETA3003 with an integrated MOSFET. It is recommended not to use the old ETA3000 chip. During the active balancing test, it was found that it would not start when the voltage difference was at least on the order of 0.01. When the voltage difference was 0.2V, the voltage difference between the two batteries could reach the order of 0.01 after balancing.
When charging, the green LED lights up. After charging is complete, the green LED turns off. When there is an abnormal charging, the green LED flashes. The IP2325 and the adjacent inductor experienced high heat buildup during charging. After implementing double-sided copper plating for heat dissipation, the temperature dropped to approximately 50℃. My skills are limited, and I lack expertise in layout and wiring. If any experts see this project, please feel free to offer guidance in the comments.
During equalization testing, one battery voltage was approximately 3.9V, and the other approximately 4.1V. A blue LED illuminated during equalization and turned off after equalization. The voltages after equalization are as follows:
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After equalization, the voltage of the first battery is as follows:
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After equalization, the voltage of the second battery is as follows:
 
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Charging data is as follows:
 
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The S-8252AAL-M6T1U is a protection IC for two 18650 batteries. It has an overcharge protection voltage of 4.2V and an over-discharge protection voltage of 2.5V, selected based on the lithium battery model. The datasheet contains protection parameters for different lithium battery models; you can choose according to your needs. Please refer to the attached datasheet for details.
After battery insertion and removal, the protection IC may fail to output even if the voltage is normal. Shorting the VM and VSS terminals will resolve this. It will not cause any problems if the battery is not frequently inserted and removed.