why won't tv work on battery backup

The battery backup is connected to your modem only not your directv

The battery back is on the TV too. Along with the STB, router, wireless, and home phone base.

If you have a BBU attached to your TV (and home phone base), it was not provided by AT&T and your question should be directed to the manufacturer.

AT&T has only ever provided a BBU that powered the gateway....never a TV or phone base.   My first modem back in 2007 had a large separate brick BBU attached to the gateway. The next gateway had an internal BBU.  The latest gateway has no BBU at all.

I speak from 13 years experience with Uverse TV/Internet/VOIP.  If you have DirecTV, I cannot address that.

It is an APC 1500. It is more than sufficient to run all the equipment for 2-3 hours. Alll the equipment stays on otherwise I would not have internet and home phone.

Is this a BBU you purchased?  If so, I'm not sure anyone here can answer your question.

doesnt directv have some sort of power inserter (cant recall the official name)inline that plugs into power as well? i have something in my attic connected to the coax thats plugged into power. if the case your satellite wouldnt work. Maybe @Juniper can respond

I have the 1500 as well. Nice unit.  
All the equipment is plugged into the battery supplied outlets?   Some of the outlets are only surge protected.  
Batteries are consumable items and will eventually wear out and need replacement.  
In any event, if the DVR and TV are on battery backup, they should stay up.  

Since the OP posted in the Uverse forum, I assumed they had Uverse TV.

@Constructive   Have you had your coffee this morning?

This isn't that hard.  I have all my uverse equipment on battery backup.  I believe it does make a significant difference.

@skeeterintexas  coffee just finished brewing havent had a chance to pour a cup yet,