Lithium Battery Charging module
There will come a time that you want to have your project mobile. The easiest way to accomplish that is with batteries and if you want to get a bit fancy, rechargeable Lithium batteries.
I am reviewing the lithium Battery Charging module that is also available from us here. It is a low-cost unit that is affordable enough to build into your projects directly without having to worry to open a box, removing the batteries for charging and then put it all back again. Except for saving on the cost of a charger you now have an easy to charge project.
Power to the board.
It comes with a USB connector to connect to a 5V power source. This is handy because you can connect the module to a computer USB port or a 5V power supply, your cell phone power supply will work great. This module also has a place to solder 5V power supply power wires directly to the board as well.
From the picture above you can see the 2 status LEDs on the Lithium Battery Charging module. The charge LED indicates that the battery is charging and the second LED lights up when the battery is fully charged.
Most of the work is done by the TP4056 IC, it is a constant-current/constant-voltage linear charger IC designed specifically for Lithium ion batteries and comes with many features including automatic recharging and is able to supply 1A charging current! You will find these chips in cell phones, cameras, charging doc stations etc.
Hooking it up is easy, supply the Lithium Battery Charging module with 5V and then hook up the battery via 2 wires to the bat+ and bat- power through holes on the board (this require soldering).
- Input voltage: 5V
- Maximum charging current: 1000 mA
- Charge cut-off voltage: 4.2 V + / – 1%
- Battery overcharge protection voltage: 2.5 V
- Battery over-current protection current: 3 A
- Input interface: Micro USB or 5V to power terminals
- Dimension: 2.6 x 1.7 cm
Changing the charging current
Out of the box, this unit supply 1A constant current to the batteries but that might be too high. It is recommended that when you charge a battery you should charge them at 37-40% of the battery capacity(in mAh). If you are charging a battery of 1000mAh capacity, you should adjust the resistance in a way that the current offered is approximately 370mA-400mA.
Now, this is my only drawback in using this module, you will need to manually replace the resistor. It is an easy process but still a bit of extra work to get exactly the amps you require. I was hoping for a variable resistor but the problem with this is that you will blow the chip if you set the resistance too low, that you will do very easily if you turn a variable resistor just a bit too far to the wrong side.
In the picture earlier you can see the resistor you need to replace if 1A is too high for your batteries. It is easier than you probably think right now, simply use a soldering iron to heat up both sides of the resistor at the same time to remove, put the new one in place and heat up each side to solder it back in place. If you do not have an SMD resistor use a normal 1/4 watt resistor, cutting the legs as short as you can.
Here is a table to work out the size of the resistor you will require:
|Resistor (k)||BAT amps (mA)|
Cheap, easy to use and it can charge bigger Lithium batteries than expected with ease. With the drawback of having to solder in a different resistor to get the correct charging current comes the benefit of being able to charge any chargeable Lithium battery at its optimum levels.