battery dies every few days

I have a 2001 Ford Mustang GT Convertible and the battery dies after a few days of the car sitting and not being driven.  I have recharged the battery a few times now (brand new battery bought a month ago) thought thats what my problem was the first time it happened (cold day dead battery) so I got a new one.  So i checked to see if I have anything left on that might be doing it.  I thought maybe a light was on but i only have 3 lights, 1 in the trunk and 2 on the rearview mirror all off.  I checked with a multimeter by removing the neg cable on the battery and wiring the meter between the - battery and the neg cable and got a 0.80 amp draw.  Is that too high for my car?  I hear a normal car should be 0.40 amp draw.  Am I doing this right?  Can someone tell me what's going on here?  This started about a month or so ago.  I have not done anything to the car recently in the last 8 months thats when I put a new system in it.  And has been fine until recently.  Could this be an alternator problem?  Is the alternator draining down my battery while it's off?  But if I drive the car everyday it's fine no battery problems at all.  This is not my daily driver but a battery should last a month without having to jump it.  My jeep sits for weeks at a time and starts no problem with a stereo system twice the size of the mustang.  Anyone here have experience in battery drain problems?  

first of all what type of battery did you replace it with, my recomendation kinda pricy but get a dry cell. like a optima yellow top. second check if you have a light in the glove box. my cousin has a roush. had the same problem too. but we found out it was the battery group too small. the way to check it is to disconnect the pos terminal of the battery get a multi meter switch it to amps. put the black lead to the battery cable and the red to the battery post itself check if theres any draw. or you can use a test light also using the same procedure only on the test light the light will light up bright if  you got something staying on or low if its kinda normal.installers do it best. we got the magic hands!

Well still having the same problem now for a while checked most circuits out for drain and nothing more than normal on all of them. (started to pull fuses is how i checked)  There is no glovebox light on my car. The only 3 lights there is are 2 in the rearview mirror for when you open the doors to illuminate the interior.  The trunk also has a light but that has been removed and not the problem and replaced after checking that.  There is no other light on the car.  Could this be a drain coming from the alternator? A bad diode in the alternator and pulling power all night to drain the battery.  The battery drains so low that nothing works at all.  The new battery is one size up from the original biggest I could get for the car when I replaced it.

If the reading of 0.8 amps is correct, then you have a major draw on your battery. The generally accepted maximum allowable draw should not exceed 0.05amps. You need to first fully charge the battery by removing it from the car and putting it on a charger. While it is charging insure that your battery cables are clean, tight and no corrosion is present. Clean the battery ground to chassis connection. After the battery is fully charged, re-install it and hook up your digital meter inline to measure current draw. You can hook it up inline on either the positive or negative cable. Deactive the doorpin circuits in the vehicle to allow access to it while you are doing tests. Depending on what type of doorpins you have you may have to unplug them or close the latch inside the door to simulate it being closed. Begin by disconnecting any aftermarket device. Don't just pull fuses for any device as you can cause a feed back problem that can screw up your tests. Unplug all aftermarket modules, relays etc. Check the reading on the meter each time you unplug something to see if the draw drops. Continue on by pulling each fuse out of the fuse box one at a time until the draw drops. Check the meter after each fuse is pulled. If nothing changes, re-install that fuse and try the next. Continue on with the underhood fuse box. If no change is noted then you need to start tracing the main battery cable. Disconnect anything it connects to such as your alternator. You will only be able to find the problem if you follow a thorough and logical diagnosis procedure. If you are lucky enough to pull a fuse and eliminate the draw, then you need to get hold of schematics to find out exactly which items are on that circuit. If there more than one, then you need to disconnect each one at at time to find the bad one.sparky

This isnt that helpful of a reply but I have a 2000 Convertible Mustang GT and I'm having similar problems. The only aftermarket thing in it is a new headunit. I got it checked by a shop I trust and they couldnt find any drains and had them put in a new battery since my other one wouldnt hold a charge anymore but I still have the same problem.

I AM invisible