Hello i have a 2004 expedition , and i have been having issues with my battery draining. about a month and a half ago i went away vacation , came home to start my truck only to relize my battery was dead. i jumped the battery drove it for about 10 miles then pparked it for the rest of the day. the next day same thing battery was dead. so i bought a brand new battery , everything was fine for about a month, i tryed to start it one day and the battery was dead again. AAA told me my altinator wasnt charging at night, so i bought a new altinator, 2 days later wouldnt start again, it seems as though this only happens when it sits for a day or so. i jumped it with a battery pack 2 days ago and havent had a problem since.

Try replacing the "convinence control module" and bad board can cause all elec issues explained and also cause engine to cut out and other things but that is where I would start, hope this helps-

I think it's doubtful that your starter is draining the battery. Once your starter is engaged upon start up, it is done with its job, and it is not needed until the next start up. It does sound like your starter is going bad. If all of the electrical parts seem to come on when you trying to start it, it should have plenty enough juice to start it. One possible cheap solution is it could be the starter relay. The relay takes power from your battery and routes it through to your starter. If this isn't working, your starter isn't even getting any juice. I hope this is the problem. I have seen many starters replaced that should not have been because fo a bad starter relay. You would have to Google that info on a Monte Carlo. I could not tell you where it is on any Chevy.

How old is the battery & have you tested it?
How is it that a month went by & your using
any vehicle that could let you down?
Why have all issues not been resolved ,as soon
as they started?
Have you checked for codes?
Have you had a professional scan tool on it
& checked data,that has to be done along with
many other checks or tests,unless it's just a battery
issue.
No one can solve any vehicle issue over the internet
There is always more to the story & you need the patient

Go to online store reliable they have repair manuals I am sure you will get the solution. Here's the link
Best Manuals

i have a 99 chevy blazer..the rear wiper motor is blown..i dont want to pay for a new one, since i barely use it..so i just opened up the fuse box and removed the fuse..easy fix..let me know if this works :)

a desconected relay will not drain the battery, you might have some other issue. start the car using boost and then check if your alternator is charging around 14 volts

ACTUALLY I HAVE A 2004 FORD EXPEDITION WITH THE SAME PROBLEM AND ITS YOUR STARTER GO OUT AND HIT IT WITH A HAMMER A COUPLE TIMES IT WILL START THEN DRIVE IT TO THE SHOP CAUSE IT NEED TO BE REPLACED THERE IS A DEAD SPOT IN THE STARTER

Is it turning over at all or is the starter at least clicking? Check the water in the battery if it has removable caps. If the water is low then fill it with distilled water. If the battery went too far down on juice it may have a dead cell and need to be replaced. You could try a slow charge for 24 hours and see if the battery makes a recovery. They make a little solar trickle charger that has a solar panel that goes on your dash and has a cigarrete lighter plug. Something like this can keep your battery from dying when on long vacations. If the car is in the garage it comes with a long cord to run the panel outside.

it could be your alternator ( generator ),,,,,have the electrical output checked, maybe just a slack wire