Very worth the time and money!! But be careful, some isolators draw amperage. The best on the market, one I use along with alot of people on here who will contest they are the best, is the Hellroaring. Go to
http://www.hellroaring.com for more info and to order. They are very helpful for help. Easy to install too. Alot of us on here can help you out with the installation. It's an automatic Isolator/Combiner. It senses charging from the alternator and brings your back up battery online, then takes it offline when there is no charging from the alternator i.e. when you kill the engine. If you do go this route, get the optional remote switch for the unit. It allows you to monitor the isolator/combiner, take it offline all the time or combine it all the time. It's something I monitor alot with the remote module. They are expensive, but well worth it! I love mine and wouldn't run with out it.