Best way to run two batteries

What's the best way to run two batteries. Don't I need some type of isolator to keep one as a cranking battery and one for my system. What do you guys think is the best way. And where can I get the stuff. Thanks.

Also curious about this. This summer I'm gonna be pushing two 500 watt subs off one amp and some polks off a 300 watt amp, and probably a couple 6x9s off my headunit, am I gonna need a second battery?

I am just getting started in setting up for this same thing--the second battery is just insurance that you can get off the lake. I am going with an automatic battery isolator that will change one battery fully then charge the other--I plan to run the stereo off the one battery and the engine off the other--RV stores carry the isolators or you can get a manual one at a boat store

One more question:

Is it better to have two identical deep cycle wet cells or one deep cycle/one cranking (both options would be set up on isolator)?

......me too but I dont have a big system so what I have decided after all the isolater perko switch solenoid discussions is to do this:

I really only need one battery so I am going to buy a strong deep cycle as my main battery...99.9999percent of the time it will be fine as I wont be running the stereo at the beach for 12 hours or anything. then I will have a second starter battery not connected to anything beside it. If I ever need it in an emergency I will use a set of jumper cables that I have in the boat.

no fuss no muss.....the second battery should remain full for a long time maybe check it once a month ..other than that it will be there if I ever need it.

for me this seemed the cheapest and easiest solution to make sure I dont get caught with a dead battery!

Hey Michael, that seems to be a great idea. I may do that instead of installing the Perko switch. Maybe I'll make up a real small pair of jumper cables too. Anyone see any problem with this set up?

......just make sure the jumper cables are of a heavy enough gauge other wise you might melt them. Shouldn't be a problem...as most boats only have the
one battery anyways ...now you have a spare. We store them for 6 months just sitting there in the winter (with the odd trickle charge)....so just having one sitting there should be fine too.

Michael, if you are going to go to the trouble to do that everytime just buy one of these.

http://www.remybattery.com/Products/Associated-Kwikstart-6250-Jump-StarterBooster-Pack__6250.aspx

....like I said....I dont think I will ever need it ....just in case!.....plus I already have the starting battery. I was given one of those things...it never worked that great....that one you show is pricy!.....you can get a good starting bat for about 80 bucks.

but yeah in the end same idea!!

we sell all types of isolators, the product that we sell the most of that doesn’t have a voltage drop are the solenoids, 100 amp and 200 amp, most info needed at this link: http://www.ase-supply.com/Sure_Power_Isolators_kits_s/20.htm

combiner. search Yandina C150 on the net.

^Mikeski, any reason you went with that over the isolator/combiner from hellroaring?

I second the combiner

Michael Z, I think you are asking for trouble. Starting batteries are not designed to be drained below about 70% or so, they are designed to give that high starting current. Likewise, the deep cycle battery is not designed to deliver the high current needed for starting, they are designed to be able to be drained way down and recharged.

Your starting battery just won't last very long if you use it that way, and if you forget to keep your backup battery topped off, you may find it can't deliver the current needed to get started in an emergency.

......hey ferral thanks for the advice.......I dont even think that I will discharge below 70 % most of the time.....I have a fishing boat that I have two deep cycles and those batteries rarely if ever got drained......they are now going on their 7th. year!
we use the nautilus batteries and the large ones have enough for cranking. If it doesn't work out I will fess up and admit my mistake!

Two batteries and a perko switch, not just so you don't get stranded but so you can play your system for a whole day or weekend. Once the music cuts out, the party is over. Girls don't like dancing to beatboxing.

sorry, brandon. you're the thread starter and your ? was best way to run two batteries. In my opinion, i like the perko switches because i like controlling which battery i use, being able turn off the battery easily (i'm not sure if isolators have off switches or not), and a friend had a bad experience with his isolator. It didn't work and we didn't know until it was too late. Haven't heard any bad stories of perko switch failure, but i'm sure there are.