battery keeps draining???

[LiquidGT]

The portable tester (the one they wheel outside) at Autozone isnt as good as the ones inside of the store.

The regulator on the alt controls the battery light, when I first got my car the regulator was bad and battery light was on, so I would have a dead battery pretty quick. A new alternator fixed it; pull it off and get it tested.

If you need a new alternator upgrade to a 3G if you dont have one.

 

[jrichker]

While the car is running pull the positive cable. If the car dies, the alternator is bad.

Bad idea, here's why...

Auto Electrics 101: Generators will run without a battery. The iron
core for the field coils will retain enough magnetism to create the
magnetic field required to make electricity.

Alternators like the ones used on Mustangs require a battery to
power the rotating field windings. That's because the AC current they
generate internally demagnetizes the iron core for the field coils
when there is no battery current to power them. The diodes inside
the alternator turn the AC current into DC current. There are 3
phases to the alternator’s internal circuitry & 6 diodes to rectify the
AC current into DC current. The battery acts like a big sink or
capacitor to smooth out the remaining pulses

Never disconnect the battery from an alternator. The electrical spike
produced before the alternator output drops to zero can damage
things like the computer, radio and even the alternator itself.

There are some self exciting alternators, but I have never seen one
on a Ford or GM car. The last self exciting alternator I worked on
was a 200 amp 110 volt one in a Convar 580 twin turboprop
airplane. That was over 30 years ago…

Here's the fix for your problem
Drive the car to Advance Auto Parts, AutoZone or other large
automotive retail chain store. They will check the charging system
for free. That way you will know what is wrong.

 

[Jack's95gt]

I had the same problem. The battery would disharge overnight. I bought a new battery and the same deal happened. I pulled every fuse and dead again. I replaced the postive cable and insulation was worn at one of those holding clips around the front of the engine. It's been fine for a couple of years now. The short was small enough not to cause a major issue but large enough to drain the battery to where it wouldn't start.

 

[Mustang5L5]

The AMP light on changes a few things. You should have mentioned it was on in your first post.

I'd pull the alt off and take it in for testing. The AMP light usually indicates alt problems

 

[ryan218]

if you need an alternator and are low on cash ( like most high school kids lol ) pm me. i have 2 extras.

my guess is thats your problem. check you ground from the battery first.

 

[ID89GT]

If your battery light is on when the car is running then the alt is not putting out a charge.

 

[red93gthb]

sorry i havent been on the net for almost a week now.

i first had taken the batt off and they used a snap-on tester inside the store

the batt light is not on.... stupid me i only remembered the light on when i was trying to start it but not when i was driving.

i took off the neg wire and put the multimeter on 10a and ran it through. i'm draining 4.20-4.46 amps(est) i pulled every fuse but it still drains. more info... can anyone help?

 

[Mustang5L5]

Wow, that's a lot! Almost 5A when the car is off??

You should be somwhere around 1/2A or less.


So with all the fuses yanked it still draws that much? Sounds like you have a serious pinch of the harness somewhere or a power wire has rubbed against the frame and insulation has worn off grounding it to the chassis.

Your next step after pulling all the fuses would be to unplug certain harnesses and try to isolate it and figure out where the short is.

Do all your bulbs work? Nothing is burned out? Have you done any work in any area of the car close to electrical harnesses?

 

[jrichker]

Possible short inside the alternator due to a bad diode. Have the charging system trested for free at Advanced Auto Parts or AutoZone or other large auto parts retailer. Or pull the alternator off and have it bench tested at the auto parts store