I have a Blue Seas 7600 which has performed without fault (6 years or so). 
"
 Voltage sensing for charge source on either battery bank
Remote sensing to avoid voltage drop issues
Low current draw: less than 12mA open, 175mA closed
Input filtering for noise rejection
Noise-free circuitry will not interfere with other devices
Current limiting allows choosing wiring for charging currents without the
need to oversize conductors for connected load currents 
Adjustable COMBINING (automatic connecting) voltage and OVERVOLTAGE
disconnect
 UNDERVOLTAGE lockout to prevent automatic closure if second battery is
discharged below 4 volts (when using dual voltage sensing)
 Indicators for UNDERVOLTAGE, COMBINED, and OVERVOLTAGE
Internal time delay prevents relay action for transient conditions, voltage must
be within range for approximately one minute to cause closure, relay will open
when overvoltage is detected for approximately 15 seconds.
Meets SAE J1171 - External ignition protection requirements
"
It has been superseded by the 7610 which differs in physical shape.

alistair

On 2011-09-21, at 12:21 PM, David White wrote:

> Does anyone have experience with either Yandina or Surepower combiners
> for charging the aux. battery (in a Vanagon or Westy)?