I echo Clives warning about Elecsol.
Further to that though is the fact that most , if not all, leisure battery suppliers will NOT warrant a caravan battery as it is left unattended and unused for long periods of time, and usually suffers problems from being left discharged for too long, causing sulphation of the plates.
They will tell ypu at point of sale it is covered, but when problems happen they will very quickly show you the small print letting them off the hook.