Help! Mustang draining the battery fast when its sitting in the garage!?

007

Founding Member
Jan 29, 2002
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I had starting issues and I replaced the old stock battery, problem is unchanged. Took the car to Ford who said it wasn't draining the battery when parked, and that it was charging ok... they thought my aftermarket chip was the problem!

I went home and charged the battery all the way, left the car in the garage and 4 days later the battery is totally flat and the car wont start! Clearly it IS draining the battery when parked.

How do I go about fixing this?

Thanks:nice:
 
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sounds like a short somwhere you disconnect the battery & get a tester hooking one side make sure as much of the power is off doors closed & as much else as you can unplug ... you can go online & get an idea on how to look for a short ... the electric fans can be trouble all new cars will drain the battery but not that fast ..check any work you nay have done ? radio , lights anything electric findind a short is hard but not impossable ...you may have even bought a clam battery .... good luck
 
Check alternator 1st. Amp draw?

4 days to drain the battery is not a short. +1 on looking at recent work. Esp audio install.

The draw should be less than 50ma after 1 hour. Get a DC amp meter/shut. Install between battery and car. Report initial amp draw and again after 1 hour.

Others may chime in about diodes in alternator. Disconnect lines to the alternator and see if amp draw goes down. If so, new alternator will fix.

If amp draw is >50ma and it is not the alternator, next step is to remove fuses one at a time and record amp draw. This will help narrow it down. There are two fues boxes. Battery junction box (BJB) and Central junction box (CJB). Report how much each fuse lowers amp draw.

Check the condition of the battery. Is it CLEAN? If acid on top, this will slowly discharge the battery as well. Clean the battery terminals as well. Ensure tight and in good condition.

Good luck. This can be a real PIA to track down.
 
If you are limited on what you have for testing tools, you can use this method. Unhook your battery negative cable and install a test light between your negative post and negative cable. If the test light comes on and everything is off ( all accesories, lights, etc.) then something is drawing from your battery. To find out where the draw is coming from, pull fuses one by one and when the test light goes out you have found the constant draw. Some components may be drawing from your battery a small amount such as audio. Hope this helps out.
 
Thanks for the advice folks. The car has had no recent electrical work. Battery is clean, no acid on it etc. Nice tight terminals. Heres where it gets weirder...

I charged it overnight with the negative side of the battery unplugged from the car. Disconnected the charger, leaving the negative side disconnected. Come back two hours later and attach battery charger again just to check it was still charged and it says its flat!? There was nothing connected to the neg terminal so should have been no circuit to drain it!? Sure enough the car wont start after I reconnected the neg side.

Now I'm beginning to think theres something wrong with my charger... maybe its actually draining the battery and not charging at all?!? I'll try charging it and then starting the car when it says its done. Its a fairly cheap Shumacher CompuCharge thingy.

Thanks for explaining how to test with the meter. I'll do that too.

D
 
the other guys gave you good advise , but you charging & what you describe sounds like you have a clam battery borrow one if you can if money is tight if the plates inside the battery start to short out you will get some weird things like you describe I would say there is a good chance its a bad battery switch it & see what happens ..... you will get it just take your time & give everything a good look over .... :nice:
 
I dont know if this will help, but I hardly drive my car and I have devices on car that drain the battery, like my alarm for instance. I can go for weeks without driving my car and my battery is fine.

I bought this thing called a sunforce 50022. its a plug in solar panel. it gives your car 5watts of trickle charged power. you dont really need 100% sun light shining on it. I had my car cover on the car and the solar panel caught dim light under the cover and under the glass.

If your car is garaged and there is a small source of light coming in, you can use it to keep your battery charged!
 
good advice...as I am having similar issues+a dead speedo. Autozone test said Alt. was down a small amount but nothing to worry about. I only have a SpeedCal and Sirius radio installed aftermarket. Goin to try the light bulb trick tomorrow.
 
I dont know if this will help, but I hardly drive my car and I have devices on car that drain the battery, like my alarm for instance. I can go for weeks without driving my car and my battery is fine.

I bought this thing called a sunforce 50022. its a plug in solar panel. it gives your car 5watts of trickle charged power. you dont really need 100% sun light shining on it. I had my car cover on the car and the solar panel caught dim light under the cover and under the glass.

If your car is garaged and there is a small source of light coming in, you can use it to keep your battery charged!
Sounds pretty effective.. I have been searching for additional source of charging battery and I think you have shared right way..
 
I dont know if this will help, but I hardly drive my car and I have devices on car that drain the battery, like my alarm for instance. I can go for weeks without driving my car and my battery is fine.

I bought this thing called a sunforce 50022. its a plug in solar kits. it gives your car 5watts of trickle charged power. you dont really need 100% sun light shining on it. I had my car cover on the car and the solar panel caught dim light under the cover and under the glass.

If your car is garaged and there is a small source of light coming in, you can use it to keep your battery charged!Sounds pretty effective.. I have been searching for additional source of charging battery and I think you have shared right way.
.
Anybody else using similar energy source?