I was wondering if someone can tell me what the difference is between installing a battery isolator and just installing a relay between the batteries on a dual battery system. I'm getting ready to put one on my bronco. In the past I've used an isolator, but Wrangler NW and Painless Wiring sell these relay or solinoid kits that seem to do the same thing as an isolator. The relays of course allow you to "jump" your primary battery from your secondary if need be. Anybody know why I can't just install an isolator and then a cheap Ford starter solinoid between the two to "jump" the primary if I need to? Thanks!