Dc to dc automatic transfer switch

Looking for a simple and easy way to use a dc generator that has its own set of battery switch to charge another set of battery's but when and or if the plug or cord is unhooked it would automatically switch back to its own set of battery's this way there is always a load on the generator. 

Hi Joe Peal,

As I understand the system that you're trying to build, you need a active components for proper switching. These would be a combination of diode and transistor since you have DC generator as you stated.

Try to make use of some solar charge controllers because it has similar concepts.

like these projects links

-> http://schematics.com/project/solar-charge-controller-14571/
-> http://schematics.com/project/mic2841a-driven-solar-outdoor-led-light-38437/
-> or related to this charger concept http://schematics.com/project/simple-auto-off-12v-battery-charger-20733/

The diode/s will be the reference. It would be a zener or you can also use a combination of passives if you want to, as long you can have the voltage level that will trigger switching of charging to another battery or load. Switching can be accomplish by a transistor or other related components that has switching capability with lesser voltage rating requirement for switching function. It is good to share the details of your project here, some experts can help you more about this.

God Bless.

Best,
Neil

I'd contact Floyd at Progress Solar in Raleigh,NC, he can figure out just about anything with nothing but I little coaching from an engineer to explain how something works to start with.