ha ! i like to think i'm competent, but i'm certainly no wiring guru , and as far as batteries are concerned other than cranking amps and storage time details the rest of it is lost on me
had a look but couldn't find the one you mentioned - the one in the PG series that looks most likely would be the 12V21 as it's quite small and at 200amp max discharge should be more than enough to start a mini. looks to hold it's charge pretty well too; 20% charge loss over 6months