Sulfates can be knocked loose from the plates collecting at the bottom of the cell eventually causing a cell to short. When it happens its usually with a battery that is well at its end in capacity and likely heavily abused.

Most modern starting batteries will suffer accelerated wear when they are drawn to below about 80-85% of their total capacity. Deep cycle batteries will tolerate a much deeper depth of discharge (DOD) before suffering accelerated wear.

Starting batteries simply are not intended to operate accessories directly other than brief high current discharges such as the vehicle's starter.

 

I just looked at this thread and had to laugh at some of your comments..I needed a quick chuckle.
I have a 2015 Explorer with the BXT-59-540 and it just died one night with no warning whatsoever. Not a bit of trouble out of it at any time, then came out to go to work and dead...won;t even take a charge.
My search on the Ford website show the BXL-59 as the replacement, but I want to take my battery and check the replacement size. I tried another of my batteries almost the same size but just can't get all the positive cables to stretch to get it on there.
I'll find out tomorrow although I'm thinking aftermarket at this point with a longer warranty.

 

Zombie thread. Sometimes it's a tight fit dimensionally to install a bigger battery. Check battery tray and all directions - H/W/L, and the ledge or foot deal that secures it on certain group sizes. As I recall my Ranger takes the same batt and it's a tight fit to put a bigger batt in, I modified the battery tray.

As an aside the battery really only has one purpose - to start the engine. All of the vehicle electrical requirements are supplied by the alternator. Battery does act as a kind of filter, smoothing out momentary power fluctuations or spikes and sags, it all works together.

 

Go to Walmart and get a group 59 battery, 3 year replacement and 2 more years of pro rate.
8 year old thread