Why such a low laptop battery capacity?

Question

laptops

Good day to all.
Notebook Dell Inspiron 7520, there is such a battery:
Dell 8858X

On the Internet it is written that 6 cell. In terms of dimensions, there are most likely standard 18650 or their closest analogues. 4400mAh is written on the battery case, i.e. it turns out about 733mAh per cell.
The question, in fact, is why such a small capacity? There are many 18650 batteries for sale with a capacity of more than 3000mAh per piece (for example, Panasonic, Samsung). And they cost quite adequate money.
A new original battery with delivery will be released for about 90 USD. It seems that the price is adequate, but with this money you can buy, for example, 10 pieces of LG MJ1 (total capacity 35000mAh). Maybe I'm just missing something out of ignorance?
Moreover, I work under Debian and there is not everything going smoothly with power consumption due to hybrid graphics.

Answer 1

In any case, the battery has a charge-discharge controller. Without it, the laptop will not accept the battery. If you connect banks of a different capacity to the original controller, then at best you will get a very bad and unpredictably working battery. At first, we tried to change the dead banks and even change the controllers in the service, but nothing good came of it.