Don't forget to ensure you get an AGM battery. I use a solar cell battery charger plugged into the 12v/Cig lighter to keep the good ladies F56 on charge. It is meant to have stop-start but it has never worked since brand new. It is an Auto which the rep said has never worked with S/start.
Not a good idea on your Mini Alistair. The power socket is controlled by BCU and times out a few minutes after stop so your battery conditioner won't be doing much. Not a good idea anyway TBH. Under bonnet the positive battery terminal has an extension and cover for easy access and be careful to use the provided negative extension as well. The seemingly convenient top suspension mount bolts don't provide a battery return. I did wonder if it's an isolated return system as on a boat.
I agree about replacing with correct AGM battery though. On our F54 Cooper D the surprisingly large 80 Ah battery must be the same physical dimensions as OE because the slide in tray under air cleaner gubbins has no provision for securing clamp to accomodate other than full length battery. Don't ask how I know this
