A lot to look at with all these answers.
Away in spain now but when we get home batteries are being moved inside under seating wheres its warmer and a b to b being fitted so a chance to make good all the wiring.
Just as an extra point, these batterys where fitted to our old adria last year and similar difference in charging and discharging existed then , just not quiet as much as now in this autotrail.
Thanks for assisting
If you answer some of the questions asked, you might get a better diagnosis.
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Ian