electronic gremlins ?

Something is likely draining your battery or alternator is not charging. Did you disconnect the blue cable?

I would expect your alternator to chuck put 13.8V which isn't enough for a calcium battery.

This is the regulator unit you need to up the voltage to 14.7v

https://www.ebay.co.uk/itm/Alternat...681762?hash=item5207c53062:g:xoYAAOSwHZBelHGJ

Using the leisure battery as a starter battery will kill it very quickly.
The cells just aren't designed to supply starting current and they'll buckle and short out internally.

When you change your battery, slacked the bolt on the earth clamp, turn on the ignition, turn off and disconnect the earth lead within 17 seconds. When the battery is changed/ reconnected you will have to enter the radio code and reset all the windows and sunroof easy job,all in the owners manual or Rave.

When you change your battery, slacked the bolt on the earth clamp, turn on the ignition, turn off and disconnect the earth lead within 17 seconds. When the battery is changed/ reconnected you will have to enter the radio code and reset all the Windows and unroof