I am a mechanical engineering student and not that familiar with electronics.
I am currently trying to establish a photovoltaic (PV) system that can charge a 3.7V 100mAh lipo battery and deliver power to a load (1.4V, 0.9mA) consistently (when there's sufficient input from PV, the battery charges and the load will be supplied by the PV <- charge mode; when there's insufficient input, the battery will discharge to supply the load.)
I have browsed some previous discussions and understand that if I want to charge a lipo battery safely according to the suggested charging algorithm, I should connect the solar panel, for example, 6V PV panel to a charging module like TP4056, and then connect the load and TP4056 with an LDO regulator to regulate the output voltage to 1.4V. However, people are suggesting that the load of the TP4056 should be disconnected while charging otherwise the TP4056 will not work properly. (https://www.best-microcontroller-projects.com/tp4056.html).
Is there any method to achieve my smart loading goal? (Providing consistent power to load either by battery/PV depending on the availability of input source.)
In this link, there is a method of using a 5V relay but as long as my input is a solar panel and is preferably a tiny system, the method should not be applicable. Furthermore, James suggested adding a pair of diodes in the circuit. However, I am a bit confused about "Add one diode between the TP4056 IN+ and load VIN+." Where exactly should I add it in the schematic? I am a bit confused about the principle behind this method.
This BQ24074 chip BQ24074 seems can achieve the goal but I am not so sure if it suits me as the maximum charging current can only be lowered to 500mA which is still much higher than 1C (100mA) of the battery I chose.
As an electrical engineering noob, I might have asked some silly questions, but I really hope someone can give me some insight into constructing this system.