As you can see in the schematic the 12V battery (or use other voltages) is connected with the plus at terminal T1 and minus at terminal T2. The contact 1 and 4 are connected together as 2 and 3 are ...
-This data sheet is for the G2RG Power PCB Relay with 1.5mm Contact Gap provides excellent isolation; general purpose load (DPST-NO) : 8A @ 250 VAC 10K. Perfect for Uninterruptible Power Suppliers; ...