I am planning to order a battery pack from aliexpress or other online sellers for my new e-bike. I have following questions;

1- I know the brand of battery cell plays an important role. If i order some with a Panasonic or Samsung cell how can i be sure if the seller really uses the original one.

2- Are the chinese made battery cells really that worse than the other asian batteries such as samsung and panasonic.

3- How can i test my batteries. ? What devices do i need and what parameters do i need to look at ?

4- How important is BMS? what things i need to pay attention in a BMS.

5- I read that many people complain about overheating in Batteries. How can it be prevented other than careful using. Do a good BMS system prevent overheating ?

6- Do i need a metal battery pack ? Can i make my own battery pack and install it in the frame using some plastic kind of bag (That i see onweb i don't know what to call for that material)>

I know i ask too many. if you guys can answer some i will be really glad.

I hope i can post my e-bike photos after assembling it.