Could this be what you are looking for?:

http://www.yandina.com/hints.htm

Automatically disable your refrigerator when there is no 12V charging
source.

This is a simple way to make sure you don't discharge or even destroy your
house battery by forgetting to turn off your refrigerator load. Many
installations only have the capacity to support the refrigeration while on
shore power or when the engine is running. But a manual switch is often
forgotten when you start the engine, wasting refrigeration time, or even
worse, you forget to turn it off and deplete your battery after the engine
is turned off.

The process can be automated by installing a Combiner 50 between the
refrigerator and the battery. One red lead goes to each, and the black
ground lead is connected to the 12 volts negative. Whenever a charging
source raises the battery voltage above about 13.3 volts, the combiner will
close and supply the refrigerator. When the voltage drops, it will
disconnect. The built in timing circuits in the C50 will prevent short
cycling that is detrimental to refrigeration motors. No power is used by the
C50 when the refrigerator is not running.

If you want to be able to manuall override the automatic control and allow
the refrigerator to run while no charging source is available, you can add a
small switch to the remote control feature of the Combiner 50.


Jim Pook
www.jimsfishing.com



"R. A. Piziali" wrote in message
...
I have need of the following:

A relay that will handle a 15amp load and close at about 13.0-13.4vdc
and
open at, say, about 12.7vdc. Is such a device available - if so where?
OR what
can I put together to operate in such a manner??

The application: I want to AC power an RV refrigerator with an
Inverter from
the vehicle DC charging system but automatically disconnect when RV
battery is
not being charged, ie, to prevent powering Inverter from RV battery.

Ray
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