About five months ago car dies at an intersection.  Luckily there was enough of a slope I could push it off to a side road.  Jump the car, runs for a little, dies.  Figure it's the alternator but I buy a new battery because my current battery was getting old and buying a battery wasn't much more than the cost of a tow truck (a new battery has more than enough juice to get to a shop even w/ a bad alternator).  Shop confirms it's the alternator and I get a nice hefty $600 bill because apparently my '05 Mustang GT uses some high-amp alternator 

Try to start the car today and it's dead again.  I think it's the battery again (when I turned on the headlights they started to flicker).  I'm going to charge the battery overnight and hopefully get it running long enough to get it back to the shop.  What has me stumped is it's a new battery and new alternator.  I'm pretty sure the regulator is internal so I'm not sure what else it would be.  I'm hoping it's the alternator and there's a warranty, but if not, what would you do?  Shop seems honest, got good reviews, would you let them fix it again or go somewhere else?  Any other part of the charging system it could be?

I'm about 99% sure I didn't leave the lights on or anything like that.

About five months ago car dies at an intersection.  Luckily there was enough of a slope I could push it off to a side road.  Jump the car, runs for a little, dies.  Figure it's the alternator but I buy a new battery because my current battery was getting old and buying a battery wasn't much more than the cost of a tow truck (a new battery has more than enough juice to get to a shop even w/ a bad alternator).  Shop confirms it's the alternator and I get a nice hefty $600 bill because apparently my '05 Mustang GT uses some high-amp alternator 

Try to start the car today and it's dead again.  I think it's the battery again (when I turned on the headlights they started to flicker).  I'm going to charge the battery overnight and hopefully get it running long enough to get it back to the shop.  What has me stumped is it's a new battery and new alternator.  I'm pretty sure the regulator is internal so I'm not sure what else it would be.  I'm hoping it's the alternator and there's a warranty, but if not, what would you do?  Shop seems honest, got good reviews, would you let them fix it again or go somewhere else?  Any other part of the charging system it could be?

I'm about 99% sure I didn't leave the lights on or anything like that.

volt meter test? any accessories? lights sounds.

Lots of Mustang guys on this forum. It. Someone will answer some of them work in shops

oreilly auto will usually check battery and alt for free.call first

volt meter test? any accessories? lights sounds.

I don't have a volt meter but pretty sure the guy at the shop will test it for free.  No accessories, car is stock.

5 months?  I would take it back to the same shop and ask what kind of warranty on parts does this shop cover.

If it is your alternator and your idiot lights are working properly, the battery light should be illuminated on your instrument panel while the vehicle is operating if the alternator is defective. When you are able to restart the vehicle, put a volt meter to the battery to determine if the alternator is working properly. Your alternator should be putting out close to 14 volts.

Maybe its overcharging.  If you take the battery to the shop and they tell you its fried it could be Overcharging.

On the other hand if the alternator has an internal short that would drain the battery. It could also charge it and reverse

How is all the grounds on the car? make sure they are not corroded either.

I see a lot of Toyotas come in with charging voltages over 15v  Those cars destroy batteries.  The only fix is to find a battery that is strong enough to handle the overcharging.
There is no one brand. Just gotta keep trying.

Assuming that the alternator isn't the culprit you're left with two alternatives. Either a short in the wiring leeching current while the engine isn't running or a crap battery with a dead cell.

If it's a short, hang on because it could get pretty expensive to find it.

If it's the battery there are steps you can take to avoid the problem in the future. First, buy a battery with the highest CCA you can get that will fit in your car. If you buy a "small" battery short on CCA it will die because it can't handle the duty cycle. The extra money you pay will be worth it in the future.

Also, some brands are better than others. Interstate sucks, I've never had a good one. I've had good luck with high end Die Hard, and strangely enough, Kirkland from Costco. The Kirkland I recently replaced in my truck lasted for 6 years, under normal usage they'll generally last from 2-4. Their return policy is great too. Personally, I don't think Optima's are worth the price unless you plan on turning your car upside down a lot.

Just my 2 cents. After 37 years of playing with cars. 

Looks like the alternator is okay, it's charging properly.  Perhaps it's a bad battery, I heard Sears recently changed their battery manufacturer to somewhere in China  but at least it's still under warranty.  If it is the battery and not a short, pretty sad that it can't even last six months.  FWIW, I asked the guy at the shop and he doesn't like Sears.  Sounded like he was saying most batteries these days aren't what they used to be, they use Delco and he also said NAPA is good.  He didn't care for Costco or Sams Club brands either.

Too busy to take it to Sears this week but I'll take it in on Monday. 

  On most vehicles, just start the car and dis-connect the battery cable with car running and if alt/gen is good, the car continues to run.
If it dies, alt/gen bad. 
If you got the boom box BS, be sure to disconnect and discharge your cap first. 

  If battery checks out good, you got a "leak" somewher in your electrical system.
Make sure your connections are good, especially ground from battery to car.

I see O'Reillys have your alt from $150-$375.
Did the shop also install ?
My 60 month NAPA bat's die in 48.
I've been using O'Reily's.

1)   If it is a short, after DOUBLE CHECKING BATTERY CONNECTIONS, trouble shoot by checking amperage/voltage  draw/drop while pulling fuses or continuity testing therough fuse box.   

2)   Garage can also throw the diagnostics on ( $100.00 unless you know SOMEBODY) and it should register the issue.

3)   Remove the positive (+) cable from the battery. Hook a test light between the positive battery terminal and the unhooked cable. If the test light lights up, then you have a draw.

"05"s hav also had issues with the dash electronics and teh OEM boom box shorting.

Delco freedom bats worked best for me.
I just read that consumer reports says the Costco Kirkland battery is one of the best.

Costco kirklands all the way.

Sounds like a parasitic drain. Probably a light on somewhere that you don't know about. Get an ammeter, connect between ground strap and studs, and start pulling fuses one at a time. It's a lot cheaper if you DIY

s197, You don't happen to have an SCT or Diablo tuner do you?  You could plug them into the OBD port and read any error codes. 


Edit:  NM, I guess you don't have a tuner.  I just saw your post saying that your car is stock. 

the 3v S197's have a problem of dying battery
my dads 08 would only last 2 days before it died
we disconnected the alarm, and presto, runs like a champ now

but mine has an alarm too, and battery lasts for 2 weeks
if its not the battery or alt, it may be some wiring problem, or grounding problem
would need some trouble shooting.
I'm not an electrical expert.
I would take it to Allen at Naka'z Car Care.  676-8937
http://www.procarcarezone.com/shops/nakaz_car_care.com
he is the Mustang expert on this island.  he's done numerous work on my 07
i trust him with my Mustang.

good luck!

I see O'Reillys have your alt from $150-$375.
Did the shop also install ?
My 60 month NAPA bat's die in 48.
I've been using O'Reily's.

1)   If it is a short, after DOUBLE CHECKING BATTERY CONNECTIONS, trouble shoot by checking amperage/voltage  draw/drop while pulling fuses or continuity testing therough fuse box.   

2)   Garage can also throw the diagnostics on ( $100.00 unless you know SOMEBODY) and it should register the issue.

3)   Remove the positive (+) cable from the battery. Hook a test light between the positive battery terminal and the unhooked cable. If the test light lights up, then you have a draw.

"05"s hav also had issues with the dash electronics and teh OEM boom box shorting.

Shopped charged on the higher end and yes they did the install.  They also replaced the serpentine belt, which was another $50 or so.  My car does have the OEM upgraded sub-woofer so maybe I'll look into that. 

Costco kirklands all the way.

Sounds like a parasitic drain. Probably a light on somewhere that you don't know about. Get an ammeter, connect between ground strap and studs, and start pulling fuses one at a time. It's a lot cheaper if you DIY

Yeah this might be the case although I don't want to rule out a bad battery just yet.  Sears should replace as it has a 3 year warranty.  I probably won't buy from them again.

s197, You don't happen to have an SCT or Diablo tuner do you?  You could plug them into the OBD port and read any error codes. 


Edit:  NM, I guess you don't have a tuner.  I just saw your post saying that your car is stock.

Yeah the car doesn't have a CAI or tune on it.  I do have a cheapo OBD II reader I bought off Amazon but it isn't throwing any codes.

the 3v S197's have a problem of dying battery
my dads 08 would only last 2 days before it died
we disconnected the alarm, and presto, runs like a champ now

but mine has an alarm too, and battery lasts for 2 weeks
if its not the battery or alt, it may be some wiring problem, or grounding problem
would need some trouble shooting.
I'm not an electrical expert.
I would take it to Allen at Naka'z Car Care.  676-8937
http://www.procarcarezone.com/shops/nakaz_car_care.com
he is the Mustang expert on this island.  he's done numerous work on my 07
i trust him with my Mustang.

good luck!

Interesting.  When you say alarm, is it aftermarket? 

I'll keep him in mind if I can't diagnose the problem myself.  I've also had good results with Wayne's Electric, but that was years ago.

yes, mine and my dads alarm are aftermarket.
so after disconnecting my dads alarm, it still has the stock security sysytem, and works fine.

So Sears says the battery is okay and won't replace it.  I told them the alternator checks out so they said run the battery again and if it dies, they'll replace it.  But before I do that, I'm keeping the old battery in to see if it discharges the same way (right now it's putting out about 12.5-12.6 volts so it seems to be charged).  As far as parasitic draw, with the car engine shut off and no lights or anything on, the draw is 0.8 mili-amps.  If it were a parasitic issue, wouldn't the amps be much higher?  I'm not sure what else I can really test with just a standard volt meter, I figure I'll watch the voltage over the coming weeks and see if it stays in that 12.5-12.6 range.