I have the original battery in 2016 MKC Reserve, BXT-47H6. It is in a tight space, hard to check fluid levels. I checked resting voltage after sitting all night and read 12.04 volts, i know this is not the optimal way of checking. Has anyone replaced with a higher cca AGM? Replacement specs group 47 and 48, any experience with these two sizes? Any tips on checking fluid?