If its not that dont know what it is! when i have my lights on after about 20min of driving they will start to purge along with accessories another 20min car will have a hard time running. Just wondering if could be alternator or a short?

 

Sounds like an alternator (possibly starting to develop a ground fault). Go get both the battery and alternator tested at an autozone or advanced auto. They do it for free.

 

+1 - sounds like alt to me too.
Quick self check - turn on car and unplug positive of battery. If car dies, alt.

 

already bought a new battery will try all of this. ty

 

When ever your lights start to dim while driving 90% of the time its the alternator not charging correctly. And its sometimes the cheaper thing to test and replace.