Ruiqi BL7212 battery pack DIY

IP2368 part refers to @wsw666's IP2368 [PD100 watt 2 to 6 string lithium battery charge and discharge module] - Jialichuang EDA open source hardware platform (oshwhub.com)
 
The battery shell needs to be purchased separately:
process the lower half of the shell as follows:
circuit board:
welding As shown below:
Prepare the battery pack according to the picture:
It is recommended to use 18650 power battery with a discharge of more than 20A. If other specifications are used, please modify the circuit. The 3 LG HG2 disassembled batteries used here have a capacity of 3000mAh, an internal resistance of 14.6mR, and a maximum discharge of 20A.
 
Finished product:
 
Assembly method:
Please use solder paste and heating table/air gun for welding;
plug-in and battery are welded after the patch part is welded;
 
solid capacitors are more recommended to be put on insulating sleeves and then welded horizontally;
the reeds of the electric drill part can be Processed with 5X20 fuse holder contacts:
Theoretically, the EMARKER part of the circuit does not need to be soldered due to insufficient power;
after soldering, please check whether the resistor and capacitor are in place and whether the pins are connected to the tin;
 
please pass the temperature measuring resistor of BM3451 through the battery pack The highland barley paper on the bottom is placed in the center of the three batteries;
please use high-temperature tape or highland barley paper to insulate some circuits of the protective board from the contacts of the battery pack above;
after installing the battery case, add structural reinforcement glue and circuit board three-proofing as needed Glue
 
on the inductor, IP2368 said to install a heat sink, use a horizontal capacitor, and fill it with silicone thermal glue. Appearance:
 
Debugging precautions:
Before powering on, pay attention to whether the IP2368, BM3451 and USB-C pins are connected with tin;
after connecting to the battery The output of the battery pack will still be 0 and needs to be activated by charging;
if the four lights flash together after connecting to the charger, there may be a problem with the temperature detection circuit. Please measure whether the voltage at both ends of the RNTC is within the range of 0.39-0.55V. If you want to shield For the temperature measurement function, it is recommended to use a forward-biased 1N4148 instead of RNTC;
 
Charger terminal LX waveform when charging with 65W PD charger:
 
Measured Honor 30S supports super fast charging, at this time the inductor battery terminal waveform:
 
Problem:
Unplug after charging The plug LED still flashes and stops after short-circuiting the USB port power. It is speculated that the 5V power supply is short-circuited here;
the stop voltage is inconsistent with the BM3451, causing the BM3451 to think that it is fully charged and turning on equalization, which in turn causes the IP2368 to never display full (sad)