LX-LBU2C Lithium Battery Charger + Power Bank 5V 2.4A - Max 6000 mAh

[Kiriakos GR]

LX-LBU2C charge controller PCB this is a find at Aliexpress. 

If you are a very careful shopper, you will pay no more than 2 Euro / dollars as shipped.
I just paid 1.95 Euro, and I an celebrating it. 

LX-LBU2C appears to be smart and modern design, it has two input ports (USB Type-C  and Type-Micro) for charging of it own Li ion cell.
And two regular USB ports, power bank output 5V.

This controller has a set of four LED as battery cell capacity and as charging indicator.
This design works well, but it is poorly documented.

LX-LBU2C activation and power off,  this is based on soft-on power.
Is is unknown to me so far, what is the minimum load that this circuit use at soft-power off.

I when lucky and I found on the web, two screenshots of basic details in good writing.
It will take a month about receiving my module, but I will use this time possessively, by adding on this article any known details about it.

[Kiriakos GR]

AI assistance ... 
LX-LBU2C is not a finished power bank, but rather a charging module for do-it-yourself (DIY) projects.
It is designed to be integrated with 18650 lithium-ion batteries and a custom enclosure to create a portable power bank.


Real world assistance ...
All generic 5V block mobile phone chargers, they will deliver 500mA as minimum charging current.
An better design of 5V block with fast-charging protocols, this might push charging current at max supported level.

It is essential at the selection of battery cells, sum of their capacity this be from minimum supported due maximum listed charging current, and higher than that.
From the other hand, if unreasonable amount of battery capacity this is installed?  This PCB will need ages to charge them. 

There is charging current limiter at LX-LBU2C
At 2.4A Max.

This translates to, operation with a single 18650 lithium-ion 2000mAh.
Second best scenario:  with two 18650 lithium-ion 2000mAh
Third best scenario:   with three 18650 lithium-ion 2000mAh

All generic 5V block mobile phone chargers, they will deliver 500mA
Under this scenario, charging current this is divided at the amount of cells.
500mA / 3 cells = 166mA per cell.

At batteries electrical specifications, there is one parameter this named as minimum penetration current for having a charge.   
500mA / 4 cells = 125mA per cell, this configuration it might work with brand new and undamaged 18650 lithium-ion 2000mAh.
But this will not work with used 18650 lithium-ion 2000mAh

LX-LBU2C PCB actual design potentials, this is a 5.999 mAh as Max power bank.
Power bank capacity this can be expanded to a greater number, only if 5V block charger with fast-charging protocols, this is used all times.
Here we come in to a new theoretical mathematical calculation,  2.400mA input / 166mA = the ultimate maximum of 14x Lithium cells.

Most common fast-charging protocols, they will deliver 2A as Max.
An more reasonable mathematical calculation, 2.000mA input / 166 mA =  12x Lithium cells.
   

[Kiriakos GR]

And now heavy duty technical details.   

IP5407 2A charge 2.1A / 2.4A discharge integrated DCP function mobile power SOC ( By INJOINIC TECHNOLOGY )

(Technology development of 2019)

https://www.injoinic.com/

Datasheet attached !!