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  1. #1
    Join Date
    Jan 2010
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    North Texas
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    1,819

    Default Lets's talk multiple battery setups. (3+)

    Lets discuss running multiple battery setups. More specifically, a 2 Stereo and 1 Crank battery setup.

    I've got the basic knowledge, as in, I know in order to wire the secondary stereo battery, you simply connect the + and the - from the primary stereo batt. Then, when the perko is on "2" it will pull equally from both batts, effectively doubling the play time. When the perko is set to "all" with the boat running, all 3 batts would be receiving a charge.

    Here is where I am unsure, is it necessary to
    A) Buy a higher output alternator
    B) Have the factory alternator rebuilt

    Beyond that, is there a "benchmark" that you pro audio guys go off of to determine when a 3rd is needed? I haven't completed my install yet, but I built everything to allow for the addition of the third in the event it became necessary. At what point is it just a waste to add? When is it absolutely needed?

    For reference, these batts will be powering a 4 amp system (2 for the HLCD towers, 1 for Sub, 1 for Cabins, and more LED lights than a boat should have. What I am wanting to cover, is that I have a system capable of providing a solid 8 hours of music without needing a start. I doubt I would ever have a day at the lake where I sat for the entire day, but it will be nice to have the piece of mind knowing that even for a 4 hour sit, I have no issue whatsoever and could go hours longer. What I am thinking to test the system ability, would be playing the system for about 4 hours non stop and then flipping my led's on and see if I can garnish another 3-4 hours from it, and have it not cut out from no power.

    I'm sure I will have more questions after getting some replies, but this should get the convo going. And who knows, this might spark up some more of my MS Paint drawings.
    Last edited by dusty2221; 01-03-2011 at 10:15 AM.

  2. #2
    Join Date
    Apr 2008
    Location
    California
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    2,840

    Default

    I personally have only seen a couple boats capable of anywhere near that and both were running six huge batts, yes i said six for around 450 lbs of weight. Both have Balmar 160 amp marine alts and onboard shore power charging systems. Both are running 1/0 gauge cable throughout the entire system.

    Of course play time is affected by equipment ratings, batt amp hours and condition, and how hard you push the system.

    I'm sure the pros can better answer this though.
    2007 Mobius LSV

  3. #3
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    Jan 2010
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    North Texas
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    Default

    Right, I understand the basics that it is affected by equipment ratings, however, I would imagine there is some "standard" that is used. And I'm with you, I have only seen a few 3 batt systems, it seems like people running more than 2 go straight from 2 to 6 or some crazy number. I'm not needing all that. Also, I have a Pro Mariner dual bank charger that gets plugged in every time the boat comes off the water, so as far as after use and recharge once the day is done, that's covered (although once we get some replies going I already have a question about this as well). I'm looking for a full day on the water situation. Make sense?

  4. #4
    Join Date
    Mar 2010
    Location
    Arkansas
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    2,475

    Default

    Is there a spec or a way to know how efficient your amps run? I'm sure there is a formula for this?
    2006 Supra 24SSV

  5. #5
    Join Date
    Apr 2008
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    California
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    Default

    Dusty, there is a way to tell and it has something to do with battery amp hours and the actual amp draw i believe, but like i said it also has a lot to do with how hard you push the system. In other words at 25% volume your batts will last longer than at 50%, 75%, etc. So there's really no standard to judge by. What type of batts has a lot to do with it as well. Way to many variables to say "this is what i'll get if i do this". The reason for the "crazy" six batt systems is to get that full day of play time and even then i'm not sure they can do it. I seriously doubt you can attain that goal on two dedicated stereo batts without running and charging unless they were massive 6 volts, super expensive large capacities or something of the like.

    3 batt systems are the norm btw for many multi-amp setups, many on here have them. Check WW and you'll see loads of them as well. For the record i'm adding a third this winters project and relocating them as well.

    KG, as for how to check how efficient your amps are? I couldn't say, maybe the pros can chime in and offer some insight on that one.
    2007 Mobius LSV

  6. #6
    Join Date
    Sep 2009
    Location
    Copperas Cove, TX
    Posts
    1,761

    Default

    8 hrs of moderate volume playing time is alot of constant playing time especially for a 3 battery setup, 4 amps (depending on specs), and lights. You might want to talk to David or wait for him to chime in. He'll probably offer you 3 or more possibilities for charging options and battery setups. I use my factory 70A alternator with no issues but I only float for an hour or so at a time. If longer it's just usually me and my girl just listening at low volume in the evening. I'm using 3 Deka group 31 batteries which are stronger than the Optimas most run on big systems.
    Last edited by you da man; 01-03-2011 at 12:53 PM.

  7. #7
    Join Date
    Oct 2009
    Location
    Pacific NW USA
    Posts
    505

    Default

    Dusty -

    This is definitely a topic beat to death over on WW. There is no standard anything when it comes to reserve capacity. There are just to many variables. It really depends on how hard you play your system, what condition the batteries are in, and so forth. If your running a full blown amplifier setup as mentioned you'd be advised to run a 3 battery setup.

    You'll find a lot of opinions on which type and what size, but ultimately it will come down to you putting as much Ah as you can afford. I'd also make sure the batteries are matched so the charge and dis-charge isnt affected.

    Simple answer =

    3 group 29 batteries
    Go with any RV/ marine deep cycle
    You cant go wrong


    Also, asks guys that are running 3 battery setups and see what type of play time they are achieving. Beware of the liars too --- I get 3 days of play at full power is, well... bs!

    -Brian
    Exile Audio

  8. #8
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    If you have a 20 amp charger then I would limit my stereo batteries to a collective 200 amp/hours which is a couple of big Group 31s. The Balmar alternators mentioned above are the real deal. Whatever you do don't use a foreign upgrade alternator that boasts big numbers on the cheap as your problems are just beginning. You can always add a small maintenance charger to just your starting battery to increase your overall capacity if needed. In most cases you can get by without an upgrade alternator but you may have to ammend that 8 hour play time goal.
    200 amp/hours will give you 50 amps of draw for four hours. 50 amps doesn't sound like alot but given the transient nature of music that is a beefy load.
    You can dramaticaaly extend the time by moderating the bass as this is where an inordinate amount of draw comes from.
    A Class AB amplifier typically generates 250 percent more heat than a Class D for example and that extra heat is pure waste. So if you increase your system efficiency by 60 percent then you will get much more play time with the same battery. This automatically reduces alot of the trickle down problems and all but eliminates the alternator discussion for most.
    Also, there is a vast discrepancy in woofer and some speaker efficiencies. So paying attention to these design and selection issues will pay big dividends in not having to over-engineer charging systems and result in a more dynamic and higher performing audio system.

    David
    Earmark Marine

  9. #9
    Join Date
    Jan 2010
    Location
    North Texas
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    1,819

    Default

    Quote Originally Posted by Brianinpdx View Post
    Dusty -

    This is definitely a topic beat to death over on WW. There is no standard anything when it comes to reserve capacity. There are just to many variables. It really depends on how hard you play your system, what condition the batteries are in, and so forth. If your running a full blown amplifier setup as mentioned you'd be advised to run a 3 battery setup.

    You'll find a lot of opinions on which type and what size, but ultimately it will come down to you putting as much Ah as you can afford. I'd also make sure the batteries are matched so the charge and dis-charge isnt affected.

    Simple answer =

    3 group 29 batteries
    Go with any RV/ marine deep cycle
    You cant go wrong


    Also, asks guys that are running 3 battery setups and see what type of play time they are achieving. Beware of the liars too --- I get 3 days of play at full power is, well... bs!

    -Brian
    Exile Audio
    I can't stand WW due to the constant barrage of idiot looking to criticize your every post, over here its to the point by some good guys.

    Ok. So based on this, it is advisable that for now, I add the third so I have two dedicated sit still playtime batteries, and leave the factory alternator as is based on the fact that I have an on-board Pro Sport Dual bank to charge and condition once the day is over.

    My next question is, my on-board is the Dual Bank ProSport 12, how would this tie into the new 3rd battery? Currently, it has leads for the existing two batts. With the 3rd bat linked to the existing stereo batt, and the charger hooked to that batt, will the 3rd receive a charge at all? How does that work?

  10. #10
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Its important that your two stereo batteries are the identical age and size since these will always be in parallel and acting as a single bank. If they are different in any way or aged and used differently then they will have different impedances leading to early failure for both. Its not critical in the case of the starting battery in that its consistently used differently and you have a dual bank charger. And this backs up my point about having total dual bank isolation while AC charging.
    Your two stereo batteries will be tied to a single charger bank and viewed by the charger as a single battery.
    The capacity of your charger is good for two Group 24s or in other words about 120 amp hours total. You can discount if you like the starting battery since that is usually put up close to a full charge. But you are at the limit for the health of your batteries and the safety of your charger.
    You can increase capacity by adding a small maintenance charger to your starting battery only. In that case you can wire both banks of the ProSport to the two stereo batteries. In this select case isolation is not required but the batteries must be identical none the less.

    David
    Earmark Marine

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