If the two outputs are of a `toggle configuration' (i.e. both are never to be ON at the same time and both are never OFF at the same time) then in my files you will find a load controller schematic built around a simple 555-timer chip, which will do this task perfectly. The PCB is single sided copper-clad for ease of construction, and includes a speed/RPM circuit that you may wish to omit as it is optional and independent of the charge/load controller. For your needs you would use a simple double-through relay. The schematic has all the documentation included. The triggering-voltages are well within your needs. A posting with additional info is here;
http://www.fieldlines.com/comments/2006/10/3/215354/941/4#4
When the batt-voltage falls below the `trigger' set-point, the relay is OFF (de-energized), and stays this way until the batt-voltage rises to the `threshold' set-point, then the relay is ON (energized) and stays this way until the `trigger' set-point is reached, etc. You may wish to use a double-poll double-through relay to gain electrical separation of the switching circuits, or what ever you wish to accomplish.
Doc.
