I had a cubot power which had an “non-removeable” battery. The running time was about two days with medium usage. I thought probably they packed every remaining space with battery which explains a non removeable one.

So I broke it a few weeks ago and decided to check out the battery. Turns out it was just that they glued the shit out of the backplate (which was more work to get of than the screen which glue already gave up) and put a normal sized battery in wich had no quick connector attached, but one of those flimsy wires that fall apart if you look at them wrong. The same shit apple introduced in their ipods.

There is and never was any reason for “non removeable batteries” other than prohibiting the user from repairing the most common failure point of a phone!