Electrical New Battery Type (size) for the Fox Body

Blown88GT

Founding Member
Nov 13, 1999
992
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Palm Beach Gardens, FL
#1
The Mustang's DieHard Silver just went bad yesterday. Voltage dropped to 1.0V on the cheap load tester.
It started right up a couple months ago & is always on a battery maintainer. It lasted 7 years, can't complain.

There are 3 US manufacturers of car batteries.
Costco, Diehard & all the others are just names they have these 3 place on their brand.
Johnson Controls
Exide
Deka

I just got a new one from AAA. They no longer spec the Group 58; it's now the Group 59.
Wasn't sure it would fit, since it's a little bit bigger. But it does fit & has a little more capacity for only a few dollars more.
I did have to change the location of the alternator fuse & the positive cable now goes across the top of the battery.
Might get a longer cable, but my current ones are marine grade.
All the online battery finders still say Group 58.

AAA has the best warranty of anyone: 3 years full + 3 years pro-rated.
The installer comes to where you are, checks out the old battery, removes it, installs the new, & checks the charging system, all for no extra fees.
I had already removed & checked min out.
My installer has been in the battery business for 25 years & he seemed to know his stuff.
He said Deka was the best & maybe the proof is the following:

It's turns out that AAA batteries are made by Deka.
Diehard Gold was Interstate: lasted 5 years
Diehard Silver was Deka: lasted 7 years
Both were used in the same vehicle under the same usage & conditions.

Deka info is here: http://www.dekacatalog.com/
Searching for the Mustang still came up with the 658MF, so searched for the 659MF.
The 659MF is spec's by Deka for other years & engines of Mustangs.
I suppose they never went back 30 years to check.
 
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John Dirks Jr

5 Year Member
Jun 28, 2013
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#2
The most recent battery I bought was from Costco for my 93 convertible. It is an Interstate brand.

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Dan02gt

5 Year Member
Mar 2, 2003
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#3
I just put a group 65 AGM from Advance Auto in mine. Fits like a glove and has authority when I start the engine unlike the small group 58 it replaced.
 

Mustang5L5

Car used in adult film "Highway Gangbang-InDaButt"
SN Certified Technician
Feb 18, 2001
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#5
Autozone battery here. I believe it's one of the models made by Johnson Controls. I had great luck with my Die Hard Gold going 10 years.
 

Blown88GT

Founding Member
Nov 13, 1999
992
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59
Palm Beach Gardens, FL
#6

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