Originally Posted by 0III0forlife
A 30amp relay is good for a pair of lights. If they are 100 watt bulbs. When the lights draw enough juice, the relay will kick out to prevent melting the wires. Its always a good idea to run aftermarket lights through a relay system, just to be safe, as well as having a professional look to the wiring.
You should never let the Daylighters on without the engine running, that could cause permanent damage to the electrical and charging system.
There already is a relay built into the wiring for the headlights, so there is no need to wire one in for them.
Most relays you can get at an auto parts store has the wiring diagram for them printed either on the packaging or on the relay itself.
That's a negative Ghostrider, our Wranglers do not have relays built into the wiring harness for the headlights, and a popular modification is to install relays in line of the headlamps to improve power distribution to the lamps and thus increasing light output. They didn't start adding relays to Wranglers until the 1997 models.
Leaving the lights on for a period of time, while not recommended, won't damage the battery unless the voltage drops below about 9 volts, at which point you risk causing cell failure inside of the battery, which is impossible to recover from.
I recommend buying a relay pack off of Amazon.com or eBay.com, just a Bosh style relay. Don't forget to buy the ones that include the sockets for simplicity. Then proceed to wire them in. You should do the headlights while you're at it, meaning you uneed to pick up some 12-14awg wire for the headlight connections, and if the wiring going to your headlights is bad enough then you'll need to get enough to do that (12 feet should be plenty). Also, don't forget to grab a couple of fuse cradles, and some 20 amp fuses.
Sending the full 13.6-14 volts directly to your headlights and Daylighters will improve light output quite a bit as well as build in some safety for your electrical system.