Idiot needing to confirm replacement battery specs
 

Idiot here. My wife has a 2005 V6 base convertible and she needs a new battery. We're looking at cheap(est) options. Looks like factory size is 96R 500CCA? Walmart has a 65 650CCA. I've read on this forum that smaller sizes should be fine? But, being an idiot, I wanted to confirm this battery will work? Thank you!

The problem with cheaper, smaller, is longevity...

Any battery that physically "FITS", locks down, and hooks up to the terminals,
will work as far as that goes... As long as the CCAs are = or > the factory
battery.

Smaller batteries are simply for smaller engine compartments in smaller cars with
different load and charging requirements. Voltage is the same, AMPs will be different,
both in load and charge. The mustang charging circuit amps may be too high for a
smaller battery, thus prematurely wear it out, and it may bulge out when hot.

The smaller battery does not have the same # of cells the larger one does, or
are not as wide; changes the characteristics of the battery. Same with like
AA, AAA, C and D toy batteries, they are all 1.5 volts, but their load capacites
are different. The "D" battery will last longer than a "AAA" battery under the same,
constant load till dead. That smaller battery won't last as long with the radio on,
motor not running, than the larger battery will.

SO, yeah, it will work, but, you won't have the same accessory time as you would
the factory one. May not be much, but less time none the less... They should both
have an Amp Hour spec, and reserve capacity spec.

The Group 65 battery is one of the finest available, if it will fit the tray. I use 65 in every vehicle I own, all 6, including F-700 big truck. imp

I use AGM batteries, personally. Awesome power, great for high power car
stereos.