Battery help

My boat came with 2 batteries and the blue sea 1,2, 1&2 switch. They have Marine Cranking on them, Interstate Cranking battery and then a sticker with 24M-XHD 800 CCA 1000 MCA. Seems to me these are both just cranking batteries. Looking at the Interstate site I didn't see a spec for amp hrs. Am I right about them being just cranking batteries or are they deep cycle as well that that will give me a few hours of play time on the stereo?

I want to add a another battery, would I need to buy the same type battery? I would like to get away from the type you add water to and go with a AGM or gel type. Could I buy one of those and use it with my current setup? Also would I just hook the new battery and my stereo battery parallel. I would like to also find a wiring diagram for a 3 battery system with the switch in the equation. Thanks

If I were you I would ditch the Cranking batteries all together. Find a Deka dealer in your area. They make very good batteries at a fraction of the cost of Optima and some of the other high end AGM batteries. They are more known for the industrial/heavy Duty side of things so maybe you haven't heard of them. Look into something like there 8A24M, 9A34M or the 8A27M.

I actually looked up Deka batteries after seeing them in another thread. Closest dealer to me is about 5 hours away.

Is this hooked up correctly? This is the way my boat was hooked except for battery 3. Would this be the correct way to hook up the third battery?

The 24M-XHD is a Marine Deep cycle made by Exide. You want a cranking battery for battery #1 and Deep cycle for #2&3. Nothing wrong with the Exide deep cycle, I use them in a setup like yours for years. Before that used yellow tops and Exide are just as good if not better. A good option is use 2 6 Volt Trojan golf cart batteries, huge reserve capacity. Would recommend installing a battery isolator such as the Blue Sea 7610 (ACR) http://bluesea.com/category/2/productline/overview/387 to keep both your house batteries and starting battery charged. Just remember that the 2 House batteries wired in Parallel need to be the same and need to be installed at the same time. A new and old battery will fight one another and ultimately kill them early.

Brett where is a good web site to see the specs on the dekas. I know I am going to need to replace mine sooner than later. I need to make sure what ever I get is no taller than 10". that way I can move them to under the seat.

Ive been looking at this one liljohn

http://www.eastpenn-deka.com/assets/base/0194.pdf

http://www.eastpenn-deka.com/assets/base/1143.pdf

Check out that link and the 9A34M. That should be the same size or very close to the Optima 34M. It has the same 20 AH rating and same reserve capacity but I bet can be had for far less than the Optima's.

John, I just measured a couple of the batteries and you would be good with group 34, 24, 27 or 31. They are all under 10" to the top of the terminals.

I had Exide's in my most recent boat when I bought it last year. The previous owner had just put them in a month or 2 before. I tested them and they were overrated even after putting a good long charge with an industrial charger on it. I immediately replaced them.

John, if you are in the SODO area of Seattle let me know. You are more than welcome to stop by and take a look at some stuff and take your own measurements.

(Message edited by polarbill on March 05, 2009)

Yes that setup will work.

You still have the battery bank (+)hot wired direct to your amps. This may lead to battery bank (batts 2&3) discharging if the system is not kept on a charger when the boat is not in use. Not a big deal. However if you want to eliminate that possibiiity then connect the (+)lead from the distribution block to the common of your battery switch instead of the battery directly.