Bought a new battery for my 08 f150, Same exact specs as the factory battery, But a tad smaller in physical shape ( 24F) stock (65). I know it will work just fine (and im to lazy to go back and change it out) but my question is does a battery that is physically smaller drain faster? Say like while playing music with the truck off? Thanks.

 

If the electrical specs are the same then no worries, the smaller over all size may make for a loose mount and cause it to wiggle around in the tray, if you can secure it form moving around your good to go.
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What you want is the correct CCA for the truck.

 

As two esteemed professionals, our colleagues, have noted above, once you have the correct CCA rating (which should be handled by choosing the correct group size battery), and the battery is securely mounted, your only concern is battery storage capacity as rated in A h/amp hours. Yes, typically a smaller battery will drain sooner when not being charged but is being drawn from with an accessory load.


You say "Same exact specs as the factory battery", so you can expect a similar amp hour rating as the battery you replaced.

 

^^^ What Apples said.. you should have a group 65 battery