Laptop (11.1V ?) battery from 6x 18650? - DIY possibility using battery housing

This is not the first time I refer to this device:

**broken link removed**

I really love it, especially the fact that it can transfer very frequently cell's low voltage to common USB voltage, which can charge various devices (with some P consumption, of course, for the driver/transformer, or whatever is in use).

However, I was wondering. Would not something like this be possible for laptop batteries? As far as I know, they are made of 6 18650's anyways. So why not to manufacture a battery housing that would be exactly the same dimensions, place similar electronics inside (it would transfer voltage to the one the laptop needs, I think it's 11.1V) and then just enjoy extra portable power?

The cells could be charged in a regular charger, not via the cable when inserted as a power source (the battery) - but maybe it would work as well.

What do you think? Is it too crazy, or does it already happen?

Thanks

Do you want to make a device similar to the Power Bank that steps up the 3.2V to 4.2V voltage of one 18650 cell to a regulated 11.1V so it can power a laptop?

If the cell is 3000mAh and its voltage is the average of 3.7V and the stepup is to 12.6V (the extra 1.5V is for regulation) then the mAh is reduced to (3.7V/12.6V) x 3000mAh= 881mAh but the circuit will lose maybe 132mAh making heat so the total capacity is only 749mAh which is not much.

Why not just use a second laptop battery?

Why don't you just get a dead or very old battery pack for your laptop, and do this to it:
https://www.linuxjournal.com/content/rebuilding-laptop-battery

Audioguru said:

Do you want to make a device similar to the Power Bank that steps up the 3.2V to 4.2V voltage of one 18650 cell to a regulated 11.1V so it can power a laptop?

If the cell is 3000mAh and its voltage is the average of 3.7V and the stepup is to 12.6V (the extra 1.5V is for regulation) then the mAh is reduced to (3.7V/12.6V) x 3000mAh= 881mAh but the circuit will lose maybe 132mAh making heat so the total capacity is only 749mAh which is not much.

Why not just use a second laptop battery?

Click to expand...

I explicitly mentioned 6 pieces, in the title. It could be more, if we would reduce the voltage, the loss would hopefully be less significant.

The procedure with a dead battery seems cool, but I am not a geek to cope with such complicated process. You also have to own lots of hardware for it, which I don't... Moreover, I would like to remove the battery easily and replace them with fresh ones fast, instead of welding circuits.

So I suppose it does not exist? I am surprised that the USB voltage reduction exists, but this not.

Today I opened an 11.1V laptop battery and found only three 18650 cells and three fake cells. There is space inside for six cells.
It was made by Dynapack in China and is rated at 2200mAh. The cells are made by Samsung (Korea?).

So you want to use a six-cells 11.1V laptop battery with a voltage reducing circuit to charge a cell phone or MP3 player with 5V? Do it with a buck voltage converter which is a switched-mode power supply regulator.