Thinking of treating the Zed (M44) to a new battery on a preventative maintenance basis as there are a few sales on at moment. Current battery was fitted by previous owner over 4 years ago. It's a Banner 55 Amp/h - 420a - 042 and struggles if the car is not used for ~a week ( which sadly happens too often) or when doing diagnostic checks unless quickly put on charge. Owner's handbook states 70 Amp/h but I have read this is very over-rated. Any advice please?