Kiriakos New Project: 14.4V 4S 12A Lithium Battery PCB with SII IC

[Kiriakos GR]

Before some time I did purchase one of these 14.4V 4S 12A Lithium Battery PCB with SII IC, so to use with it some Lithium batteries from a working battery pack coming from a laptop, which died due an accident.
The owner of it was not that gentle to it. 

Either way those healthy 6x Lithium Batteries plus this controller is about having a second life, as I am planing to use this power pack as rechargeable source that it would power up the headlight and tail light of my bicycle.

Currently this project of my is at the Stage 1 ....  That is testing of the circuity.
By adding the batteries to it I got 15.4V right away.
This translates that my cells are 4.2V its one and so the expected output is 16.8V Max
   
When I was shopping for this board I also got five DC-DC 3A Buck Converter Adjustable Step-Down, therefore I can use these to step down the output of the master pack at any specific voltage that I am going to need.

Basically if I manage to get from this project enough power to hold the bicycle lights at full power for two hours I would be totally happy from it.

The project will be hosted in a waterproof box, that it would be permanently installed over the bicycle.
All details will posted in time.   

[giorgos]

Very nice project!
It is very nice to have a bicycle too, it doesnt require to spend money for fuel, also its good for your health.
Regarding step down regulators, I have use them many times.
 http://www.ebay.com/itm/gib-Buck-Converter-Step-Down-Adjustable-Converter-Power-Module-Regulator-LM2596-/171264824047?pt=LH_DefaultDomain_0&hash=item27e02dd2ef
They are very useful cheap and suitable for a wide range of applications.

[Kiriakos GR]

Yes  LM2596 is my choice too. 


Back to my stage 1 testing...

By using one 12V 21W bulb as load managed to create a flow of 2A so to benchmark my batteries.
Instead of using data logging for having data of the actual discharge curve,  decided my first test to be more primitive by using just my eyes and a timer. 

The battery pack managed to work at 2A for 60 minutes and after that mark and in the next three minutes the battery voltage started drop down below 12V amazingly fast, so fast which I did not manage to record the actual CUT-OFF voltage.
I thought that I would getting at list 75 minutes by it and I was relaxed by moving around in my workshop, but I did not.

My first impression about this circuit it is very positive, even by be that tiny the load of 2A for 60 minutes it was not enough even to heat any electronic part over it = frozen.

The batteries it did become hot by reaching a temperature of about 40C.
After CUT-OFF my next thought was to recharge the batteries at the suggested max battery voltage of 16.8V but my power supply measured 6A and I though that is best to wait first so the batteries to cool-down before the next charging cycle.

The battery cells does not have printed specifications over them, but my opinion now is that they are at a minimum 2000mAh, which translates that their health are good and they can be trusted.

[Kiriakos GR]

After some time and by finding an suitable box, I thought to further improve this project.
Found three used Samsung ICR18650-26F from a dead laptop, these cells are in fantastic condition.
And I am going to finalize this by adding a power switch, and female banana jacks.

I am working on the final details right now. 

[Kiriakos GR]

R&D team of ITTSB made it after all. 

This is the final look of this project,  and I am very happy because I did managed to use several parts which I was have all ready.
The power switch is a used but high quality (made in Japan), also added to it an 12V LED which other than working as power LED this at total darkness works also as a torch light (approximately 100 Hours).
And finally the addition of nice soft silicon pads, makes it unmovable over the bench.