Big Bear Battery issue

Tried starting up my 05 BB this morning after about a month of sitting. Wouldn’t, so i jumped it off with my truck. Ran fine and I let it run for about 15min. Turned it off and tried to start it without the jump and I got nothing. Shouldn’t it have charged by running? Does this mean I need a new battery, or should I have actually given it gas and rode it around? Thanks