AA size NiMH have a capacity of between 1500mAh and 1800mAh so
charging at 170-190mA will take about 10hours, add a bit for losses in
charging and 12hours will see them tippy toppy. Best not to leave
them on charge at this rate continuously, my (slow) charger has a
cutout at 16hours to stop overcharging.

HTH

Also, only charge them that long if they are empty. Better to use a smart
charger.

Bob.