Andrew Gabriel wrote:

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

If your charger is properly voltage regulated, the charge current
will drop to almost zero when charged. If it's not properly voltage
regulated (and many aren't), the charge current won't drop to zero
ever, and you may wreck the battery by leaving it charging too long.

I'm not sure. The instructions warn that it doesn't automatically stop
charging, but the current does diminish as it charges - whether this is
through regulation or the effect of the battery's increasing charge I
don't know.

You also need to be careful about the max charging current, again
depending on battery type. Charging at 1/7th of the battery capacity
is safe with just about any type. Some batteries (e.g. car) can
safely be charged at significantly higher rates. This is the max
current though when the battery is pretty flat. As it charges, the
current will drop.

Since you haven't said exactly what type of battery or charger,
can't be more specific.

It's a car battery.

Daniele