Andy writes

I disagree. It is generally accepted that the 1/10 rate is the
desired rate to charge a NiCad without overheating. Once the
cell is fully charged, you can THEN overcharge it if you leave
it there..... So 1/10 for about 15 hours is a good rule of thumb
to get to full charge...... If you want to "float" it, drop the
charging
current to 1 or 2 ma to just equal the self-discharge rate.

Andy