Was pulling out of parking lot and every light on dash went on. Tested battery and it needed replaced. Purchased new Battery and drove car all day running errands. New battery drained and all dash lights came on again. Removed Alternator and it tested out perfect. Baffled about what the problem is.
2007 GT Battery draining, alternator tested good
- Thread starter salcourt
- Start date
MassMustang
forum member
I've had similar issues a handful of times but a battery charge and driving time resolved it. Always seemed to happen after really cold or really wet weather. Also, a couple of times when I thought I left the radio on when I shut the car off. I know the radio was shut off but when I went to turn over the engine the radio came on automatically.
Others locally mentioned something about faulty Shaker radios. Just a theory though.
I'll be watching this thread for some ideas and possible answers!
Others locally mentioned something about faulty Shaker radios. Just a theory though.
I'll be watching this thread for some ideas and possible answers!
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BruceH
BBB Big Bore Boss 322
It's probably the alternator. Could be a corroded ground but most times the alternator and battery need to be changed at the same time. Yes, it tested good but not all places test them properly.
That's all I have, hope you get it figured out.
Shaker radio option?
S8MS-01904
I fix things
I know of a workaround for the Shaker500 radio. It defeats the shuffling of the CD drive.
Dino Dino Bambino
I have a red car
The Shaker 500 ICE system may not be switching itself off after you shut off the engine and open the driver's door, causing a parasitic drain on the battery. It's been known to happen so as gray06gt said, check the amp draw.
If that checks out OK, it's likely the alternator's at fault and it wasn't tested properly. I suggest you start the engine and while it's idling with no electrical accessories running, check the voltage across the battery. That'll tell us if the alternator's working as it should.
If that checks out OK, it's likely the alternator's at fault and it wasn't tested properly. I suggest you start the engine and while it's idling with no electrical accessories running, check the voltage across the battery. That'll tell us if the alternator's working as it should.
86GT351
forum member
/\ image fail
An alt with a bad diode can read good voltage. Need to test the diode if you think it's the alternator. Trust me, I'm about to put my sixth alternator in.
redfirepearlgt
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Welcome to the site.
As gray06gt stated, with the key off check the current draw with a clamp style amp meter, or current clamp in conjunction with a compatible meter rated for measuring D.C. current. An AC current device will not work. A DVM can be used. However most DVM's are rated only to measure up to 10 amps without the addition of a current clamp measuring device.
There will be less than one amp current draw for a period of time just after the car is turned off. Assuming all lights are off and doors are closed, etc. That current less than 1 amp if I recall is part of the memory relay circuit. It will drop out after a period of time (don't know exactly that value).
If current is present say 1 amp or greater, look on the battery for a rating called Ah (amphours) NOT COLD CRANKING AMPS OR CRANKING AMPS. THAT IS DIFFERENT. Take the Ah rating and divide in by the current value you read on the meter. That will tell you how long the battery is taking to drain down. E.G. Battery Ah = 72. You read 8 amps of current draw on the battery with your amp meter. 72/8=9. Therefore on a fully charged battery uit will be rendered useless of ALL current in 9 hours. It will likely be unable to crank the car in much less but will give you basic lights and so forth.
If there is no current draw on the battery with keyoff. You have two obvious culprits. Either the alternator is crap, OR you got a crappy battery to begin with. I had that happen with Advanced auto parts batteries. I highly suggest staying with a Motorcraft battery or within the family of the Motorcraft battery MFGR.
If a current drain remains present all you can then do is begin pulling fuses until you find the system causing the current drain. I'd start with the radio since it has been known to cause issues as mentioned. If other electrical mods have been added to the car recently such as a Boost-a-pump, stereo upgrades, fancy neon lighting, etc., remove those sources first to see if the current drain goes away. Good luck.
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Dino Dino Bambino
I have a red car
That's correct, and you can even get spikes of higher than normal voltage with overcharging of the battery when a diode is failing. I agree that a diode check would be the next step after ruling out a parasitic current draw and a faulty alternator regulator.
The only thing different is that the electrical plug/connector is in a different position and orientation. I don't know if the stock harness will reach but my modified harness did not and I just extended the wires for it. Ford wanted $55 for a new connector with 8" of wire. I said no.
06 T-RED S/C GT
forum member
So what exactly is your workaround/solution for defeating the shuffling of the CD drive ? Here's my workaround.. Pull the shaker/radio fuse !
MassMustang
forum member
I'm curious as well. What's this solution to the Shaker head unit shuffling CDs (or whatever else may be draining the battery)?
My battery issue has gotten worse this past month. I've had to jump start the car every weekend. I'll have to test again, but in previous testing, with the car running I believe the battery tested at 14V+. I haven't testing the draw/load on the battery with it off yet. I'm curious if I need a battery or an alternator though.
Dino Dino Bambino
I have a red car
Sounds like the alternator's OK but the battery's on its last legs.
redfirepearlgt
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I tend to agree with Bruce that the alternator is not being tested completely. Just because it can generate voltage doesn't mean first it is generating any current, and second doesn't rule out failure of the blocking diodes to stop current back feed that would generate a drain.
However get a current clamp measuring device capable of measuring DC Current. The cheap ones only measure AC most of the time and most multimeters can only measure a max of 10 amps before blowing the safety fuse. Disconnect the alternator prior too with care to not touch the engine with the positive wire that feeds the battery. Check current draw with the amp clamp at the battery then. If minimal current, hook the alternator back up and see if the current goes up again. If yes, def the alternator as Bruse has said. If no, begin pulling fuses until the circuit causing the problem is isolated. When current drops to less than 100mA or so you have found the circuit. Report that back and someone can work through the electrical circuit for that system with you to isolate further.
Seems like I remember the basic battery used in a Mustang is rated at about 60-80Amp hours. So if during 8 hours of usage the battery is flat and won't turn over the car that means there is a minimum 10amp current draw with the key off on an 80Ah battery. That's a lot of current and will make a very nice spark so be careful. 10A x 12vdc = 120 watts of power.
Remember that CCA is not the same as amp hours. CCA is a burst of current for starting not the actual current the battery can produce over a one hour period before being dead (Ah).
MassMustang
forum member
Quite possibly. It's gotten worse since I got the new 326 stroker and Novi 2200 installed. I'm hoping it's simply the battery and not a short or something.
06silverbullet
forum member
buy a pioneer call it a day.
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