The positive terminal of the lithium-ion battery and the positive terminal of the charger are likely to touch, but there is no problem. Because they are connected.
The MAX17201 communicates with a PC via I2C. This development kit included a USB interface and configuration software.
A typical capacity estimation IC needs to set a lot of parameters, but Maxim prepared the configuration wizard that can be set these parameters interactively. Using this, I set the battery capacity to 3,200 mAh, the battery type to NCR, and the other items to default.
It is recommended that this battery be charged at 0.5 C, so I set the maximum current of the charger to 1.6 A and the standard voltage to 3.7 V. And started charging. The MAX17201 evaluation software screen looks like this:
The software displayed the charging voltage, open circuit voltage, charging current and temperature, as well as the battery SoC. We can see these time change graphs.
In part (1) of the figure, we can see that this charger precharged this battery with a low charging current (0.1 C) , 1/10 of the typical charging current. When the precharge process was completed, the battery level increased significantly. Next, this charger was charged with a constant current (CC) as shown in part (2) of the figure. After that, the battery was charged at a constant voltage (CV: constant voltage) as shown in part (3) of the figure. The SoC evaluated by the IC was 62.5% when this charger determined to be finish charging.
In the experiment, I also tried discharging at 0.25 C.
This software can monitor the status of the MAX17201 registers.
Also, it is possible to prevent the contents of the nonvolatile memory in the TC from being rewritten.
In addition, it seems that it is possible to set a 160-bit challenge word setting to prevent forgery of the battery.
Through this experiment, I deepened my understanding of lithium-ion batteries. I will try to obtain various data while keeping safety in mind.