Just been having a look at the Varta website and a few other sources to try and understand a bit more about this. Redredzimmer is correct that the AGM/gell batteries should have a different charging cycle. No idea what sort of charger VW would have fitted to a Beach (mine is 2012 and pre EHU). I would suspect a basic split charge relay from the alternator.
I have added EHU myself to the van and for keeping the leisure battery topped up while on site I use a standalone CTEK charger which has the ability to select either ‘normal’ or ‘AGM’ mode. What I don’t know is if I put an AGM or gel battery in would it be damaged by being charged in a ‘normal’ mode while driving. Seems from one site I was on (
http://www.batterystuff.com/kb/articles ... s-agm.html) that a good quality charger / alternator will be OK for AGM but a Gell type needs a special profile or additional regulator. I would now be happy to replace the existing one with a deep cycle flooded type but an AGM or Gel needs further research & advice!
The choice of potential batteries will be restricted by the space (height) under the seat anyway. Wish I had measured the existing one when I had the passenger seat out .
If there is 190mm of space there then there are options in deep cycle flooded, gell and AGM batteries. However I also saw this one
http://www.alpha-batteries.co.uk/leisur ... e-battery/ which is for VW under seat fitting and that is only 175mm high. Seems it’s a ‘semi’ leisure battery from the conflicting description & spec. (leisure battery but in spec says deep cycle = No).
But …reading this article (
http://www.aandncaravanservices.co.uk/b ... nology.php) it suggests that we might well be better off with a normal battery anyway. The Bosch S5010 and Varta Silver 85Ah mentioned are both available in 175mm high and look strikingly similar to the one fitted to the Beach.
My brain now hurts so will stop worrying so much and enjoy the cool beers and wine from my coolbox regardless of how its powered.