Handheld battery question

My brain has totally gone blank for this simple question, I know I should
have paid more attention in school !!!.

I just was given a 12volt 1200mAh battery and a 200mh 3W wall charger by a
friend who is quitting flying. It has been that long since he used the
battery he doesn't remember charging times etc.

So the obvious question is, how long should it take to full charge this
battery using the supplied wall charger ? By the looks of it, the charger
looks like your standard charger, no auto cutofff etc.


Rob.