The relay you linked to can switch 15 amps, however, I don't see a reference to AC or DC current? The reason I suggested an automotive relay is because these relays are designed to switch DC current. That is important, very important! Thus I would use an automotive relay. The fact the contacts are rated for 30 amps is fine. Most common automotive relays, generic in flavor are 30 to 40 amps rated. That is great for your application. They can also be had for about $5.00 give or take from any auto parts supply store.
You could likely use AWG 20 for the relay coil. That coil will not draw much current at all.
This link should be to a Tyco pretty generic automotive relay. Look at the VF4 series. The data sheet(s) on these relays shows the coil voltage at 12 volts (with plenty of room) and the coil resistance of about 90 Ohms. That tells us at 12 volts the relay coil will draw about 133 mA. Not much at all. So lets say at the cap where we get our DC we measure about 22 volts (E peak at the cap less a few volts) So I want 22 - 12 = 8 / 133 = so I want about a 60 Ohm maybe 2 Watt resistor.
The reason for all the "approximates" and "abouts" is because this is not a very exacting science. The 12 volt coil actually will run fine at 14.5 volts in an automotive system and actually pull in as low as about 8 volts.
Just make sure you place a diode like a 1N4004 across the relay coil with the diode band (cathode) on the positive side. Place the resistor on the positive side. Keep all commons at common. Use the relay to switch the 12 volts from the battery or your other 12 volt source for the outside lights.
Hope that helps
Ron
You could likely use AWG 20 for the relay coil. That coil will not draw much current at all.
This link should be to a Tyco pretty generic automotive relay. Look at the VF4 series. The data sheet(s) on these relays shows the coil voltage at 12 volts (with plenty of room) and the coil resistance of about 90 Ohms. That tells us at 12 volts the relay coil will draw about 133 mA. Not much at all. So lets say at the cap where we get our DC we measure about 22 volts (E peak at the cap less a few volts) So I want 22 - 12 = 8 / 133 = so I want about a 60 Ohm maybe 2 Watt resistor.
The reason for all the "approximates" and "abouts" is because this is not a very exacting science. The 12 volt coil actually will run fine at 14.5 volts in an automotive system and actually pull in as low as about 8 volts.
Just make sure you place a diode like a 1N4004 across the relay coil with the diode band (cathode) on the positive side. Place the resistor on the positive side. Keep all commons at common. Use the relay to switch the 12 volts from the battery or your other 12 volt source for the outside lights.
Hope that helps
Ron