If I don't keep my phone at 100% while at my desk, and then I go out somewhere after work, there's a chance my phone will run down to 0% while I'm out, potentially stranding me somewhere.

I don't think that's OCD. It's just planning ahead.

What kind of phone do you have? I get 2 full days use on a charge. Surely you need a new battery instead?

If I'm in an area with good connectivity I can easily last two days with my OnePlus. On the move, though, or in bad signal areas, and 20 hours might be the limit.

People who always plan ahead to a T (to keep their phone 100%), have some OCD. I should know.

I used to live life at the edge and only charge my phone at 1%. Then a relative had a medical emergency and I had to stay at the hospital for hours, and my phone lost power so i couldnt call anyone. Now I always try to keep it fully charged. So no this is definitely not OCD.

You only did it after a medical emergency. If the drive to do it was innate without any "hard lesson" required, it would be OCD.

Compared to tons of people who couldn't care less on living on 70% or 50% or 20%.

Learning from other people's mistakes is OCD?

People with OCD still learn from their own and other people's mistakes and adapt their own behavior.

It's not the learning part that's important, it's how one applies what they learned, and the way they act on what they fear might happen that can fall into OCD.

An obsession with being always 100% charged when you leave the house, immediately plugging to charge etc, always checking to make sure, etc, can point to OCD, even if it "makes sense" (e.g. to avoid being ever stuck without charge in an emergency).

OCD is obsessive compulsive disorder. Learning from people's mistakes is unrelated.