In my experience it depends on the phone DC input, usually under
firmware control.

Measure current over time on the DC input to document behaviour.

Some phones reach charged state and disconnect the DC input, then draw
almost no current until either battery voltage falls, or estimated
state of charge falls below something like 90% or 95%, then they
reconnect until charged.

Some phones reach charged state and disconnect the battery, operating
from the DC input until the DC input is removed.  Of these, some won't
track estimated state of charge during the self-discharge phase, and
some will.

One device I have goes one step further; if you leave it connected for
a week, it presumes you plan to leave it connected forever, and says
so; it disconnects the DC input until estimated state of charge
reaches 50%, then transfers the load to the DC input.

Thus it entirely defeats the idea of keeping the device _ready_ for
use on battery in this way.

--=20
James Cameron
http://quozl.netrek.org/
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