Is it possible to connect a 12v battery?

[altdelay]

I have a power supply with 12v output.
Do I need a voltage reducer? which one? I'm lost

https://es.wikipedia.org/wiki/78xx
in the wiki there is a table that says in 2,2v-30v

[Xavier]

A 12v battery would make the 7805 (5v converter) super hot.
9v is the maximum you should use.

Yes it can work with up to 30v but only if you need very little current output.
With the preenfm2 9v is tht max if you don't want it to get toot hot and die.