Looking for a small exhaust fan for the bathroom
 

I have small square shaped vent in my bathroom. But it is very weak in terms ventilating the air and mold is starting to form on the ceiling. I was wondering if anyone has any suggestions for a small exhaust fan that i can attach to the vent.

My requirements are the following.

It is easily attachable. I have no problem having to glue it on.

It has to be battery powered. It would no be possible for it to be powered by
an electrical cord.

Thank you!

Not going to happen. There is no glue on battery fans.
And why can this fan not be hard wired?
Is this vent pipe on a wall or the ceiling? And where does this vent run to? Do you own this home? Is it a two story or one story?

Box stores have a huge selection of exhaust fans. Look through what they have, it might suit your needs.