The Right Way to Hook Up a Relay to 12 Volt Power. While you might be tempted to just run the positive wire from your relay directly to the positive terminal on the battery, that is a big no-no.

MSD's new Stand Alone Solid State Relay ($153.95; PN 7564) simplifies wiring and features LED indicator lights. It does the job of four relays with minimal wiring. It's another method to consider ...