I have a TP4056 Lithium ion charging breakout board. I am just trying to use a single 3.7v 18650 battery which would power a small stepper motor and Arduino.
I have one of the TP4056 boards that has additional circuitry for (what I believe to be) load control, so in addition to +/- in and +/- battery on the board, there is +/- out. You can see a picture of the board here: http://www.coldtears-electronics.com/images/TP4056-4.jpg. There is also a helpful video at https://www.youtube.com/watch?v=Qw4psECqpwI that reviews this board.
I can get the board to charge the battery fine, when it is just the power input, the TP4056 board, and the battery. I can also get the battery to power the load (stepper + Uno board) fine, when it is just the battery + load, and also with the TP4056 in between the battery and load (although haven’t run it down to test the undervoltage protection yet).
What I am struggling with is the relationship of the charging side with the load side.
With the load connected it seems to prevent the charging from shutting off: the charging seems to go on forever, even when the load draw is very low. My anticipation was that eventually the charging would stop. I also don’t want to overcharge the battery, and was wondering if the load is interfering with the detection of when the battery has reached max. This issue is also raised in the video link above.
I did a search for TP4056 on the forum, but I was unable to find anything that discusses this.
Any suggestions? The load needs to be constantly connected to the power, as the Arduino runs continuously with a sketch to determine when the stepper will run. I contemplated putting in a switch, but disconnecting the load during charging would defeat the purpose of the project.
The power source is also various. Right now, I power it by periodically plugging into a 5V power supply, but may add in a solar input in the future (with an input in the 4v- 8v input range of the TP4056). However, if I can’t get this chip to charge properly when a load is attached, no point in getting the power supply working!