Should I charge my NiMH batteries longer the first time than I would times after that?

Answer 1

most chargers turn off once the battery is fully charged, leaving the battery on the charger longer has no effect on the charged state of that battery

Answer 2

I would agree with the previous answer, but would like to expand. There are generally two types of chargers, peak and timed.

Peak chargers have technology to detect when a battery is fully charged, or at it's peak, and then the charger stops, or slows to a trickle to maintain the peak state.

Timed chargers work on a timer and charge the batter for the set time. They will charge until that time expires regardless of whether or not the batter is fully charged, not charged enough, or worse, over charged and possibly damaged.

Armed with this knowledge, what you now need to know is what kind of charger are you dealing with. My guess would be peak, in which case it should have some sort of indicator that the charge is complete, either an audible tone (beeping) or a light (red light turns greens, etc). Once that charge cycle is complete with a peak charger, you should be all set to disconnect the charger and use the battery for its intended purpose.