GMC Repair: dead battery, gmc yukon xl, 2003 gmc yukon xl

Question
QUESTION: multiple times go out in the morning and battery is dead,, replaced battery works ok for while and dead battery again. could be 1 week could be 1 mouth. had charging system and battery checked, both ok. no lights are being left on. any ideas?
ANSWER: Hi
What year/,make/model vehicle do you have?
Thanks

---------- FOLLOW-UP ----------

QUESTION: sorry,,,2003 gmc Yukon xl,,,if you jump off will work for while with no trouble...

Answer
Hi
This could get pretty complicated. My first advise would be to preform a parasitic draw test on the system. You will need to check the amperage draw on the vehicle at rest. Anything over approx. 30mA (0.030 amps) is usually too much. The computers or modules of vehicle  stay "alive" using a small draw of battery power when the vehicle is not running. (eg the clock, radio presets, personilized settings etc...). The sum of all these modules total should not exceede the 30mA.  The reserve capacity (RC)of a battery multiplied by 0.6 gives the approx. avalible Amper hours (AH) from full charge to total battery rundown. Somewhere in this figure your battery is reaching overnightwhen it is dead in AM's.It could be anything that could stay on when the battery is off. That means that there is a " Current Draw" on the battery that runs it down overnight, like a light on as you stated. How to find it? Intermintent draws can be time consuming to locate. It could be a module that is staying fully "alive" with key off. It could be an open circuit in the Alternator windings.  If you have some electrical experience I'll be happy to help you attempt to locate it. Granted there may come a point where a Tech 2 GM Scan tool will be needed to watch the "awake" condition of the Modules in the vehicle. If this point is reached, You may need to take it to a repair facility that has access to a Tech 2 Scan tool. My first step will be if there is any aftermarket (Non GM Equipment) installed (Radio's, DVD Players, Amps, electric brakes, etc...) would be to un plug any of them at a time or all overnight and see if one of them is the culprit. Any New additions to vehicle lately? I have seen a cell phone charger that was kept plugged in draw a battery down overnight. Do the kids keep the Playstation plugged in overnight? Any of these and countless others.. so you see It could be very complicated yet it could be very simple. Let me know what you would like to do, and I;ll help you as much as I can.
Please keep in touch.
Paul