I have used both the Yandina Combiner 100 and the SurePower 1315 for
auxiliary battery setups in Vanagons.  While both of these are pretty decent
units, I definitely prefer the Blue Sea Systems ACR 7610 as my number one
choice for an automatic charging relay.  The Blue Seas unit is built tougher
and can handle more amperage than the Yandina or the SurePower.  I also like
the fact that the connector posts on the Blue Seas 7610 allows you to choose
the wire gauge that you use for your installation (10GA to however thick you
want to go) vs. the standard 10GA input wire on the Yandina.  Here is a link
for the 7610 ACR:  http://bluesea.com/category/2/productline/overview/387

There is some info about using an ACR on my website listed below as well.

Hope that helps.
Jay Brown
'85 Zetec Westfalia
https://sites.google.com/site/vanagonheadlightrelays/

Date: Wed, 21 Sep 2011 12:21:27 -0700
From: David White <sirgrumpsalot@GMAIL.COM>
Subject: aftermarket aux. battery combiner
Does anyone have experience with either Yandina or Surepower combiners
for charging the aux. battery (in a Vanagon or Westy)?