I have a cell phone, it came with a charger. The charger
delivers a full amp. This is quite a lot. So much that it a:
charges the battery nice and fast, which is useful when
you
need it, and b: makes the battery quite hot, only nice if
you have a cold hand, which in my case is rare*.
Now,
heat is one of the things that degrades lithium ion
type batteries. Sometimes, I simply don't need to
charge
my phone super quick. So, put a current limiter on the
charger, so you can charge it at 0.1/0.2/0.5A or
whatever,
if you've got a long time. Thereby preserving your
battery.
Later on, this could probably be built into the phone
software, so you could tell the phone to be ready by a
certain time, for example when your morning alarm goes
off. But for now, a standalone charger is the way to go.
* I have loosely coupled mitochondria, that's a northern
European heritage for you.