Not related to OS10 but it is a serious flaw none the less. On my Samsung you have to almost destroy it to get the battery out. A lot of phones have that issue. I do believe Apple pioneered that feature.
I try to never let it get below 40%.
You don’t have to do that. The battery management software in modern laptops and personal devices is designed to ensure that the battery is neither overcharged, nor allowed to discharge too much.
Given this, the true enemy of battery life becomes number of cycles, and even then, the batteries last many, many cycles.
You’re better off just using the device normally and either charging it at night (if you use it heavily), or just overnight when you need to (if you don’t).
At least it’s not NiCad.
Which Samsung?? I have several Samsung Android devices (but not a phone). Accessing the battery is dead easy. There are several videos on YouTube that show the technique.