My boat has dual batt that has perco switch. I want to add 2 more batterys that just run the stereo my ? is do most people run the two that are going to run stereo to the alternator or not.If so could someone show a diagram of how this is done.

how old are your batteries currently? What type of batteries do you currently have? There are a lot of options of brand, type and size. My guess is you have some standard marine/rv battery. Get rid of those completely and get 3 dual purpose or better yet AGM batteries in a group 27 or 31. Group 31's have almost double the reserve capacity of the group 24 batteries found in a lot of boats standard. <BR> <BR>To wire you will hook up one that will run everything expect the amps. If you can, run the deck off of the stereo bank as well. The other 2 batteries will be hooked in parallel(positive to positive, negative to negative). So you will have your main starter cable hooked to the "common" terminal on the back of the perko, the starting battery positive will go to terminal "1" and the positive for the dual batteries for the stereo will go to terminal "2". You can hook all 3 of the batteries negative terminals together. <BR> <BR>I would leave the switch in the "both" position unless you are sitting listening to music with the boat off. At that point turn the switch to position "1". This will isolate the stereo and starting banks so your stereo is only draining your stereo batteries leaving you with a fully charged battery to start the boat. Then after you start the boat you can then turn the switch back to "both". This will charge all 3 batteries together. It is also very important to invest in a high output alternator or an onboard charger. The onboard charger is a much cheaper option and that route most people go with.

Wake, <BR> <BR>In a battery switch scenario, all electronics, helm buss, amplifiers and alternator should be wired directly to the Perko switch common lug. There are few exceptions like a bilge pump/float switch for a boat stored in water. The stereo source unit, other audio electronics and amplifiers should never derive power from separate input sides of a switch as this can create noise and is potentially harmful to the audio electronics. <BR> <BR>For preservation of your alternator, its recommended to use a voltage sensing solenoid (SurePower, etc) rather than a manual dual battery switch. But if your total batteries are going to exceed three Group 24s (one starting and two utility) then I would use a cascading scheme whether automatic or manual and gain an understanding of how to correctly manage the manual switches. Or, get an increased capacity alternator. <BR> <BR>In any case, a multi-bank multi-stage smart AC shore charger is very important to battery longevity. You don't want to solely rely on the alternator. You need a charger with a capacity equal to or greater than ten percent of your total amp/hours. Plus, you'll need a method to isolate the banks while shore charging, and in particular to circumvent the solenoid isolation if applicable. <BR> <BR>There's no such thing as a perfect charging system that corrects for everything. But you can come very close and in the process extend your play time at rest, protect your alternator from excessive loads and heat plus dramatically extend the lifespan of your batteries. <BR> <BR>If you follow Brett's recommendation and run two total Group 31 AGMs, you can rotate your batteries or battery functions and extend them a little further. <BR> <BR>David <BR>Earmark Marine

Not to hijack but, <BR> <BR>I'm installing a second battery on my 24v. Which one of the Sure Power switches will I need. So with the Sure Power I won't need a perko switch, it will do everything automatically??? <BR> <BR>Sorry for the question my super sport had a perko and two batteries and I was always running them dead. So I really want to get it right with this boat.

<a href="http://continuouswave.com/whaler/reference/dualBattery.html" target="_blank">http://continuouswave.com/whaler/reference/dualBattery.html</a>

I'm installing the Blue Sea add a battery system this weekend if the parts arrive on time. This thing allows for full seperation of house power from cranking power. Also all you have to do is turn it on and you don't have to mess with it for the rest of the day unless, you totally drain one of your batteries. When it charges, it charges battery 1 first then automatically begins charging battery 2 once battery 1 reaches certain level. The diagram show a 2 battery scenario but you could wire a 3rd battery to the 2nd battery in parallel. <BR> <BR>Manufacturer PDF documents included in the link below <BR> <BR><a href="http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/270541/377%20710/0/bluesea/Primary%20Search/mode%20matchallpartial/0/0?N=377" target="_blank">http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/270541/377%20710/0/bluesea/Primary%20Search/mode%20matchallpartial/0/0?N=377</a> 710&amp;Ne=0&amp;Ntt=bluesea&amp;Ntk=Primary Search&amp;Ntx=mode matchallpartial&amp;Nao=0&amp;Ns=0&amp;keyword=blu esea&amp;isLTokenURL=true&amp;storeNum=5002&amp;su bdeptNum=9&amp;classNum=12106