Is it possible to use normal batteries on vex cortex?

I have an upcoming competition and I bought everything-- but I forgot the special vex batteries.

Is it possible to just wire a 9v battery to the port, or it does have to be specifically that kind of special batteries?

Thank you!

For competition, you must use VEX supplied main batteries. I am fairly confident you will find some teams that can loan you batteries at competition.

Good luck!

Are you talking about the backup battery or the main cortex battery? If it is the main battery then I would take @lacsap’s advice. If you are missing a backup battery (9v), you can stop at a Pharmacy or convenience store that’s near the event. Any 9v will do, but make sure you have the adapter to connect a 9v to the cortex.