Chewing gum battery charging

I had nothing to do, so I took apart an old shaver and got two AA rechargeable batteries. I originally wanted to use a lithium battery charger to charge them, but I found that the charging voltage was only 1.4V, and two in series would only be 2.8V, so I Want to make a lithium battery charging system myself

CN3085 is a chip that can charge and manage nickel-metal hydride batteries. It can charge and manage single to three-cell nickel-metal hydride batteries. The device includes a power transistor internally and does not require external current sensing resistors and blocking diodes. CN3085 requires only very few peripheral components and is very suitable for portable products. The thermal modulation circuit can control the chip temperature within a safe range when the device's power consumption is relatively large or the ambient temperature is relatively high. A high-precision voltage comparator is integrated into the chip, which can accurately set the constant current charging termination voltage. CN3085 does not require additional components such as blocking diodes and current detection resistors, and only requires very few peripheral components, making it very suitable for portable products. The charging current can be set with an external resistor, and the maximum charging current can reach 1A. The power management circuit inside the CN3085 chip automatically reduces the charging current when the junction temperature of the chip exceeds 135°C. This function allows users to maximize the use of the chip's power processing capabilities without worrying about damage to the chip or external components due to overheating of the chip. In this way, users do not need to consider the worst case when designing the charging current, but only need to design based on typical conditions, because in the worst case, CN3085 will automatically reduce the charging current.