Dave - I believe that batteries fitted to new cars are a higher spec than replacements - correct!
Batteries are essentially a 'grudge' purchase - nobody wants to buy one, they only need to buy one when they can't get their car started........it's easy to get a cheaper one on the replacement market - as long as it starts the customer is happy. It's a binary result - no sliding scale of performance.
BTW, which part of God's own county are you in? When I lived near Halifax (Midgley)the water was so soft it would chew through central heating boilers like Fat Bastard at a buffet table.
