Chest display power question.


New Hunter
Hi all. I have a question about my chest display I got off Etsy. He has it listed as 5 volt and suggests using a portable power pack charger. Well when I hook my daughters pack up it works great, for a few second than shuts down. If I push the button on the pack it comes on again for a few seconds. Will I have this issue with any power pack I buy? Any other options? Thank you