D.M. Procida wrote:
The charger says it's running at about 3 amps. When can I consider the
battery properly charged?

On some battery chargers - when the amp meter drops to zero (on the old one
that I use anyway)
When the batter hydrometer says so (if you can get at the individual cells)!
When a voltmeter says so!
When any indicator on top of the battery says so - usually turns green (on
the battery on my car at least)!

The manual for the charger is unhelpfully vague, merely saying in poor
English that when the pointer is "in the left part of" the scale that
charging is complete.

Or when you can start the car on a chilly morning using battery power alone.

Cash