How intelligent is the charger?  If I forget the MA2 battery and it remains on the charger hours after the indicator has told me the battery has completed charging, will this harm the battery?   Or is the charger intelligent enough to shut down and stop charging?   It would be nice to put batteries on charger at bedtime and remove then 7 hours later in the morning.  I do not want t mess these batteries up.   Thanks for the knowledge.  

They are smart enough not to over charge.  I do the same as you. leaving them on overnight.  But it's probably best to remove the batteries as soon as you can after they are fully charged.

I attend to my batteries (watch out for them) while charging. I am confident in the DJI charger to fully charge and then discontinue (not over overcharge). For me, an evening charge while relaxing and all is clear. It is a pleasure to glance at the circle of lights and then go "off" when complete. I think, not to  worry if you overnight charge in safe conditions. DJI moderator may wish to weigh in.

Here are the official DJI disclaimers on maintaining the intelligent flight batteries for the Mavic Air 2: -

Hello there Soybean Farmer. Thank you for reaching out and for the inquiry. The DJI Mavic Air 2's intelligent flight battery has an Overcharge Protection function. The said battery stops charging if an excess current is detected. Thank you and fly safe always.