dual battery banks

http://store.altenergystore.com/Blue-Sea-Systems/m115/Inverters/Inverter-Accessories/Battery-Switches/Blue-Seas-Battery-Switch-Selector/p4750/

this might do it.  i wish we had a picture though

if this is not the right part, this brand is the most common for things like that.

james- Alt-E staff

Nathan, I think you need to give us more information on exactly what (and why?) you are trying to achieve.

You might be able to find a large Schottky diode (or use several in parallel) that can prevent current flow between two batteries, or at least current will only flow from one to the other. I have come across configurations like that where a large battery system charges a smaller one, and the charge in the smaller system is preserved for emergencies, but both batteries would not be connected to the same load.

If you place the diodes in the line from each of the battery banks to the inverter then those same diodes that prevent current flow between the batteries would also prevent current flow from the inverter/charger back to the batteries so they would never get charged.

John