I picked up a Stinger SPP680 for a pretty good price, but I dont think it will suffice and my primary battery. What I want to do is be able to play music, dvds, etc with my car off while having the reliability to start it back up when Im done. I know there will be limitations on how long I can use accessories with my car not running but I would like to some recommendations to help me extend the time. From what I've read, it seems like my best option would be to get a good starting battery, such as an optima red top and have it isolated from a deep cycling battery such as the SPP680. I've also read that having a deep cycle battery and starting battery connected to eachother will reduce the life of both batteries, will the isolator prevent this? and if so, does anyone know a good website to pick up a good isolator at a decent price? thanks in advance.