I have a Mk7 TSI, it has the original battery , which has now dropped to 12.2 V when left overnight or charged. Alternator is fine as well over 13v when engine running. The OE battery is a EFB 69Ah 360a, I need to replace it. I was going to fit a Bosch EFB 70Ah 650a. I have been told I will need...