Optima Battery Question and how much juice do I need

[Chexi]

Yes, I would imagine that 4 blue tops would power the audio for a long time. However, I am spending so much money on restoring my boat already that I am trying not to spend where I don't have to. I also have an Air, not a Super Air, so I do not have as much room. Storage space on the boat is at a premium. I can put 2 Optimas as far forward under the observer's seat as they will go and not really lose any useable space. More than 2 and it becomes interesting.

What I am doing to my boat you ask? Well... I am replacing all the vinyl with new skins from Christine's (which required me to also buy a pneumatic stapler and compressor), adding isolator/combiner, new power wiring, new tower speakers, new cabin speakers, adding Wetsounds WS420 EQ, adding a distribution block, adding a support floor in the rear hatch so that I can add ballast on top of the factory ballast which required me to buy 3/4" plywood and a good amount of epoxy resin and hardner, replacing batteries, upgrading the alternator, adding a flush pro, replacing blower and blower hose, and possibly recarpeting the boat. I'm sure I forgot a few things in the list, but you get the idea. So you can see, I think I'm probably spending enough.

[gride300]

you can mount blue tops at any angle if that helps.

[01superair]

Chexi - each one of those pictures is one side, total of 8 blue tops and the alternator is a 210 amp Balmar. You can put 3 in the open bow under the seats and 1 more on each side of your rear ski locker.

[Chexi]

8 blue tops! You must be able to jack up your stereo, go away on vacation for a week, come back and still have it playing.

Yes, I could put 3 batteries up front and 2 in the back, but I'm using the entire rear hatch for storage and ballast bags. I know that batteries back there are ballast, but I want the ability to control it. I also want the extra space for when I don't have the ballast full. I also want the space under the bow seats as I might be putting the under bow seat Fly High Pro bow sack. However, if I find that just the 2 batteries do not meet my needs, I can add more to the bow I guess and lose the fat sack. Adding any to the rear is my last choice.

I have 1 marine starter (was in nose) and 2 marine deep cycles (were in rear) that are only a year old and worked fine, but they are traditional liquid batteries and the deep cycles are too big to put anywhere but the rear hatch. In the short run, if I need only 1 extra battery, I wonder if I could use the 1 year old liquid marine starter for the cranking and use the 2 optima duos as my deep cycles. They would be isolated from each other via the Blue Seas system except when I manually overrode them on the rare occasion that the starter needed an assist to turn over the engine, so I don't think I'd run into the charging issues associated with different types of batteries. Anyone have any experiences with doing something like this?

[kaikane]

The starter battery/deep cycle setup is very common in motor homes & larger cruiser boats. Essentially having a starting battery/curcuit & 'house' battery/circuit for long term power needs. In general the biggest difference between battery types are what purpose they are built for. There are essentially two core battery classifications, Starting (measured by CCA, cold cranking amps...how many amps can be supplied in a short burst) and deep cycle (measured by Amp Hours...discharge rate at 5amps per hour). The number of batteries is not as important as their duty and capacity.

Starting batteries are built for short bursts of maximum power...they do not last long supplying power over extended periods of time. In fact I have seen starting batteries go completely dead in 45 minutes powering stereos in boats & hot rods. The deep cycle battery will last according to amp hours, based on your discharge rate and can supply hours of extended use without fail. For example...if you're stereo system pulls a total of 5amps and you wanted to know how long a 100amp hour battery will power the system the math would be (100AH/5amps=20 hours to 0%). FYI, you seldom want to allow a battery to go below the 60% capacity rate since that will shorten the battery life and can damage electrical components due to inadequate current supply(12.3 volts is considered a 60% voltage...12.7 is considered 100%).

In fact, starter batteries can usually only go below 60% 3-4 times before they lose a cell or get cooked. Deep Cycles can go below 60% more frequently without damage but it will dramatically shorten the lofe of the battery. Another thing to note...deep cell batteries take longer to charge where starting batteries can fully charge in a matter of 10-15 minutes by a standard 80/100 amp alternator. I woulld keep that in mind when figuring out what you need.

I have a 2008 236 with a stock dual bettery setup (two Marine duty batteries rated at 80 amp hours...marine duty is considered a hybrid starter/deep cell battery...ok but not great at both pursposes) and have a moderate stereo system that pulls 10amps at normal volume loads. At the end of a normal playday (music & pulling) the batteries are at about 60% capacity. Enough to start the motor and get me back home but not for back to back days of all play and no charge. When the batteries go bad I will upgrade at least one to a 12v 200AH deep cycle battery (I have 4 in my motor home for dry camping) that should provide 2-3 days of carefree playing on the water.

Best bet is to figure out what your amp requirements are and build the battery bank from there.

[wake4life6]

I thought you weren't suppose to put batteries on their side?

[ZANDERSANTE]

optimas you can. Not acid filled and completely sealed.

[TravisFling]

AGM = Advanced Gas Mat so AGM batteries should mount at any angle, right?