Bought my 2006 Mustang GT brand new in Feb 2006. In August 2009 the battery went out. Gave me a nice warning so I got it replaced with a Diehard Gold and went on.

The next year my alternator went out. Did some research on the forums and noticed many people had this problem with earlier cars so I got the part # they said was better.

Now this morning my 2 year old battery just gave me clicking noises. It has been a little cold here and I have not driven it since Thursday. I took it to Sears and they said it is good after they charged it. I put a meter on it before I took it and it said 8.5V which is really bad. Lead acid batteries should never be allowed to get that low.

tl;dr questions

Did Ford majorly goof on the size of these batteries? My V8 F-150 has a 700cca battery in it.

I didn't leave anything on (lights, etc) so I really don't trust this thing. Should I go back and demand a exchange from Sears?

Would a larger battery help solve the problem? While at Sears I looked at this one and it will fit in the battery tray:

Sears Link

It has 880cca, compared to the 590 of the 40R I have now, and the puny 500 of the 96R they suggest to replace it with these days.

 

Welcome to the forums!

I also have a 2006 GT, although I'm the second owner.

I think this might be good to read:
http://www.batterystuff.com/tutorial_battery.html

Two interesting points made in that:
and
This last I find *highly* interesting. Given where the battery is mounted, and the exhaust temperatures seen in that area, and (last I looked) no venting for that area... it may in fact be no wonder the batteries are dying... They're being baked?

While I'm at it:
Which is alarms, clocks, and volatile memory...like the map the computer builds for it's air/fuel mixtures.

Now, as to CCAs vs longevity... looks like it isn't the issue. It's more use and temperature, looks like to me...

 

Ive read other opinions on heat killing them too...think about it- how many other cars have their battery in a insulating blanket- it certainly aint to hold heat in.

I saw AM sells hood heat extractors- not a big fan of AM, but I always liked the idea of extractors...wish someone made a nice set with catch trays/drains for wet weather- these cars need them.
Ive often wondered if the cowl plastic was cut if it would simply vent out the back- think it would help

 

Do you have the Shaker 1000 system? If you do, that might be the culprit. I'm working on my fourth battery I think. The amp for the Shaker system had a short in it that causes it to stay on even if the car is off. I had it fixed once under warranty. It usually is only a problem if I let it sit for a couple of days, especially in the winter. I just pull the fuse around the start of november and put them back in at the beginning of April.

 

Yeah the battery I was thinking to buy instead and linked in the OP has it all over the factory battery in all of those numbers. I doubt they did it with decreased life because the Free Replacement period is shorter.

I have the standard Shaker 500 radio, and no alarms or anything, car is bone stock as I bought it.

I like all of your ideas but I think Ford just goofed on this charging system. In order to get to work, I pulled a year old battery out of a Taurus I NEVER drive and it started it right up. Instantly noticed how much faster the starter turned. I later looked and it is rated over 600cca. A V6 Taurus.

 

I might catch some flak for this, but I think a lot of it is Ford is kinda cheep when it comes to the mustangs- dont get me wrong, love the cars- but, look at the cheap carpet they picked for it, the lack of sound deadener in the wheelwells, even the smallish battery...yes MAYBE those three were to save a pound or three 'for performance', but I'm betting it was more to cut like 20 bucks unit cost per car... I think the toilet paper at work is thicker than the mustangs carpeting

I'd like to try a optima battery, but I'm too cheep also...not sure how much better theyd hold up, but bet it would be quite a bit. after some reading about what kills batteries, thinking about putting batterytenders on everything over winter- but perhaps just pulling the cable would do almost as much...
our 65 galaxie battery is a cheep autozone one thats 9 yrs old already, still going strong - but without even a clock, that car draws zero milliamps when off...never had a car that bled zero before- and never had a 9 year battery before. AND that car sits 99% of the time (only about 2000 miles since we got it in 2002).

I think what kills these is the memory circuits pull even more than older cars, and with the smallish battery- and many sitting a lot over winter- the batteries sulfate and crap out... during summer, heat soak adds to their demise...I think when storing if simply disconnected, they would fare YEARS longer...

 

Im going to agree with you here. My battery was only 2 years old. At the beginning of the summer my alt. jsut crapped out with no warining and took the battery with it. The shop replaced it with the factory battery and Im not impressed with it. Would love to updgrade to an optima or similar battery for the next one.

 

to add to this, I pulled the factory shaker 1000 amps. Replaced them with one 4 channel (no sub yet) and it causes my lights to dim(uve got to be kidding me). The elec. system is very weak

 

Don't bother with the Optima. I put a yellow top in and it killed it just like all the others i put in. Right now I'm running an Interstate from NTB and I pulled the fuses for the amp. It's a really a mix of weak electric systems, lots of power draw when it's not running for the alarm, letting it sit for too long with out driving it and cold winter days. If I had a garage I would just get a Battery Tender and plug it in all the time. I may even move the battery to the trunk and get a solar charger to see if that helps. Would be alot easier!

 

O wow ok. Thanks for the heads up ob the battery!