Monday, November 27, 2017

DIY Powerbank 2017-A

In search for an easy to make power bank diagram? Here is one for you.

To keep things easy and simple different modules have been used instead of discrete components which greatly reduces the amount of work to be done however a few capacitors will be needed.


Main features:



1. Use of Lithium Ion cell. 18650 cell with protection will be perfect.
2. TP4056 based Lithium Ion charger.
3. A7530 based DC-DC boost converter. 

Extra components required


2 100uF 16V Capacitor.
SPST switch.


This diagram is easy to understand and make but the main limitation will be the amount of power it can deliver which is not that high.


The modules:

First module that will be used is a TP4056 based single cell lithium ion charger. It charges through a micro USB port which is very convenient. It can charge at up to 1A of current which is moderately fast. This module also has Two indicator LED for showing different status. Link to the datasheet is added to the bottom section of this post where a detailed information on what the indicators mean can be found. The only modification required is to solder one 100uF capacitor on the Input pads, minding the polarity.

4056 Based Lithium Ion charger Module


The second module is an A7530 based DC-DC converter. As you might know the voltage of USB port is 5V where lithium ion delivers around 3.7V-4.2V. So Voltage has to boosted up. This particular module do just that, it has a USB port on the output section that can deliver about 800mA so not that powerful but should get the job done. It comes with a 100uF capacitor on its output so nothing needed there. It also has an Indicator LED on board which will light up during operation.

A7530 based DC-DC Converter


Choosing the lithium ion cell

18650 cell with DW01A and 8205A based lithium ion protection circuit will be ideal for this. If your charging module already have protection you can use unprotected lithium cells as well. Two or more cells could be used in parallel although make sure to use similar cells. The only modification needed here is to add a 100uF capacitor across the cell.




Connections

This is how the modules and other parts will be connected. 


Very small amount of soldering has to be done with this project. On the Lithium Ion charging module a 100uF capacitor is soldered across the input pads. From the output of this module two wires run to the Lithium Ion cell. Another 100uF capacitor has to be soldered across the cell. I would recommend using 18650 battery case and soldering the capacitor across it which not only omits the necessity of soldering wires across the cell itself but will also make it easily swappable. From there those two wires run to the DC-DC voltage boost module, a switch can be added between the battery and the boost module to turn it on or off and that's pretty much it. Put everything in an enclosure and you are good to go.


Resources:

1. Datasheets.
2. My full blog.



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