I was led to believe that the difference between N and S batteries was not the number or thickness of the plates, but the strength of the electrolyte.
This was gleaned from an intelligent engineer who was in the industry 30+ years ago, and of course things have changed for the max profit mindset, so who knows if it still remains true or partly true, or partly true sometimes.
For the flooded batteries with removable caps, of the marine and starting batteries I have dipped with a temperature compensating hydrometer, the electrolyte has ranged from 1.270 to 1.285 when fully charged, and newish.
But when the batteries are low on water, it is far easier to get a 1.285 reading, and when refilled that same battery struggles to read 1.270, even when it is held at high voltages and physically agitated to thoroughly mix the electrolyte.
Likewise when low on water, just above the plates full charge resting voltage can read abnormally high, and when refilled abnormally low.
I believe the CCA can be manipulated just by the strength of the electrolyte.
Each 10 degree C in rise of the electrolyte doubles the rate at which the sulfuric acid solution eats the plates, so manipulating its strength can certainly affect the amount of warranty returns.
I would be interested if Southern batteries do indeed ship with ~1.265 max strength electrolyte, and northern batteries ~1.310, as that engineer claimed was truth 30 years ago.
Either way I think that blanket statements should be taken with a grain of salt or 2. There's some findings in the following link which go against the common beliefs, regarding plate number and thickness of starting vs marine batteries.
Light Cycle vs. Deeper Cycle NOTE: This article deals with FLOODED marine batteries, not AGM or GEL batteries. The Problem: The problem, as I see it, is one of dishonest marketing where multiple battery types wear the same clothes (sticker) and will perform differently when
marinehowto.com
