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Old    Nathan Fransen (natemx231)      Join Date: Feb 2012       02-28-2012, 9:54 AM Reply   
So I have a question to see if I'm on track for a proper battery bank to go with my stereo and alternator. I have a 2003 SAN 210 with a stock 70 amp alternator. I plan on keeping the Kirkland 27 group on switch 1/starting battery. On switch 2/stereo bank I'm going to buy 2 Deka 8A31DTM in parallel. I have three JL amps XD 600/1 sub, XD 600/6 boat and a HD 750/1 tower. So 1950 total amps. How long of run time can I see while the boat isn't running and do I need to upgrade my alternator? Does anyone have any better options or ideas? I'm hoping Brett Yates (polar bill) will respond.

Thank you for input Nate.
Old    Hate2party (slipknot)      Join Date: Aug 2001       02-28-2012, 10:03 AM Reply   
Nathan I am also looking for an answer for a 2000w system? I have a 100a alternator though. Polar Bill is the guru from what I have read so far. Thanks for chiming in Brett with your vast knowledge and expertise. I may go for the sealed batteries, I want the Group 31s in parallel as well. The prosport Mariner 20amp onboard charger should work for me? As I only have a two bank system. 2 starters and 2 stereo batteries.
Old    TJ (Houstonshark)      Join Date: Jan 2011       02-28-2012, 10:38 AM Reply   
Polar Bill should be given a sticky for 'Battery System Design'. I think there's 3-4 recent threads going now, including mine from yesterday.
Old    Brett Yates (polarbill)      Join Date: Jun 2003       02-28-2012, 11:33 AM Reply   
Sorry guys, rally busy at work. Hopefully I can get you some info by the end of the day. David is probably better then I am because he has more experience with how the actual stereo works with the charging system and he is very technical.
Old    Earmark Marine (david_e_m)      Join Date: Jul 2008       02-28-2012, 3:03 PM Reply   
No one can answer with absolute certainty about your individual play time. Sure you can calculate wattage based on the specific load impedance divided by amplifier efficiency divided by voltage divided by the transient nature of music (since we are not calculating the run time of DC bulbs here) in order to arrive at an amperage draw and compare that to half of the amp/hour capacity of the stereo battery bank in order to keep the consumer grade batteries healthy long term. Past that there are way too many variables like how accurate the amplifier power specs are, how you play the system whether at clipping, - 3dB or -10 dB, what percentage of charge the batteries were at when beginning, how efficienctly the system was engineered and tuned (this factor alone can easily double or half the play time), EQ settings, are you running the sub and in-boats along with the tower speakers while at rest, quality of downloads, type of music, just to scratch the surface.
But you might think in terms of 50 amp/hours of battery reserves for every 1000 watts of AB power played for every hour with an average system.
With certainty I would use an AC shore charger that is at least 10 percent of my collective amp/hours.
For alternator capacity consider that the factory rating is with higher rpm and for intermittent periods only. Add 15 amps minimum for ignition and boat operations without DC lighting plus the total stereo cuurent draw while at play plus what current draw the depleted batteries represent after a long duration at rest.

David
Earmark Marine
Old    Nathan Fransen (natemx231)      Join Date: Feb 2012       02-28-2012, 10:30 PM Reply   
Quote:
Originally Posted by david_e_m View Post
No one can answer with absolute certainty about your individual play time. Sure you can calculate wattage based on the specific load impedance divided by amplifier efficiency divided by voltage divided by the transient nature of music (since we are not calculating the run time of DC bulbs here) in order to arrive at an amperage draw and compare that to half of the amp/hour capacity of the stereo battery bank in order to keep the consumer grade batteries healthy long term. Past that there are way too many variables like how accurate the amplifier power specs are, how you play the system whether at clipping, - 3dB or -10 dB, what percentage of charge the batteries were at when beginning, how efficienctly the system was engineered and tuned (this factor alone can easily double or half the play time), EQ settings, are you running the sub and in-boats along with the tower speakers while at rest, quality of downloads, type of music, just to scratch the surface.
But you might think in terms of 50 amp/hours of battery reserves for every 1000 watts of AB power played for every hour with an average system.
With certainty I would use an AC shore charger that is at least 10 percent of my collective amp/hours.
For alternator capacity consider that the factory rating is with higher rpm and for intermittent periods only. Add 15 amps minimum for ignition and boat operations without DC lighting plus the total stereo cuurent draw while at play plus what current draw the depleted batteries represent after a long duration at rest.

David
Earmark Marine

Thanks for the reply. With everything you said and the research that I have done I'm going with the 2 deka batteries. Do you think the 70 amp alternator will handle the boat and the combined 210 amp hours in stereo batteries? If not how big of a upgrade do I need.

Thanks for your input, Nate
Old    Earmark Marine (david_e_m)      Join Date: Jul 2008       02-29-2012, 6:04 AM Reply   
With only a 70 amp alternator you may have to keep the stereo bank off-line from the charging system after a very long period playing the stereo at rest. Under those circumstances something has to give whether it is the stereo or stereo battery bank. An ACR would help this out and automatically protect the alternator. However, after a significant depletion, the ACR may not combine and your stereo could be out of commission for the remainder of the day until you get to shore. A manual switching scheme in combination with the ACR would provide options. You are going to be very dependent on AC shore power and an ACR will only increase that dependency. Get a quality 30 amp charger. So, if you are going to get by with a 70 amp alternator then everything else has to be in place without exception and you are going to have to gain a circumstantial understanding of how to use the ACR and manual selection options.

David
Earmark Marine
Old    Brett Yates (polarbill)      Join Date: Jun 2003       02-29-2012, 12:57 PM Reply   
Quote:
Originally Posted by david_e_m View Post
With only a 70 amp alternator you may have to keep the stereo bank off-line from the charging system after a very long period playing the stereo at rest. Under those circumstances something has to give whether it is the stereo or stereo battery bank. An ACR would help this out and automatically protect the alternator. However, after a significant depletion, the ACR may not combine and your stereo could be out of commission for the remainder of the day until you get to shore. A manual switching scheme in combination with the ACR would provide options. You are going to be very dependent on AC shore power and an ACR will only increase that dependency. Get a quality 30 amp charger. So, if you are going to get by with a 70 amp alternator then everything else has to be in place without exception and you are going to have to gain a circumstantial understanding of how to use the ACR and manual selection options.

David
Earmark Marine
What he said
Old    Bruce Mac (brucemac)      Join Date: Dec 2005       02-29-2012, 3:20 PM Reply   
Quote:
Originally Posted by david_e_m View Post
However, after a significant depletion, the ACR may not combine and your stereo could be out of commission for the remainder of the day until you get to shore. A manual switching scheme in combination with the ACR would provide options.
David
Earmark Marine
related question David

is this because (using the 1314 as an example) the 1314 tries to combine both banks, they equalize (i'm assuming this happens fairly quickly) drawing down the primary below the seperate threshold of the 1314, it then seperates the banks and then the process repeats almost in a continuous loop/cycle?

if this is true, then i've been agonizing over this for the last two years. i get a good solid day or day and a half and that's about it. doesn't matter how many long sets or garbage/ice runs i make, the stereo bank is dead until i get home and plug her in.
Old    Earmark Marine (david_e_m)      Join Date: Jul 2008       02-29-2012, 4:02 PM Reply   
Bruce,
Its the same with all voltage sensing ACR/VSRs. If the battery bank capacity is moderate, the stereo is moderate and the depletion level is moderate, then it won't be long with the engine running at decent rpms before the charge is sufficient on the sensing side for the relay/solenoid to combine and stay combined during the entire trip back to the slip or trailer. But as the stereo gets bigger and bigger, as a result the battery bank reserves need to grow and the greater voltage depletion after a long period at rest represents a more serious amperage load, the ACR/VSR can attempt to close but the voltage immediately sags and it bounces open for the long term. It may attempt to repeat the cycle but the result is the same. So the stereo bank once depleted may never see the alternator again that day. If you have a smaller alternator it is less able to stiffen the voltage making matters worse.
So as systems increase and you are dealing with various sizes of alternators or stators the behaviors of ACR/VSRs change and you have to address this by modifying the scheme. We don't do a one size fits all.
You will be more dependent on shore charging in any case. If you don't have shore charging you can easily begin the following weekend in the hole. That's bad for your battery performance and longevity not to mention your stereo comprised of unregulated amplifiers may be performing at only a fraction of their potential.

David
Earmark Marine
Old    Bruce Mac (brucemac)      Join Date: Dec 2005       02-29-2012, 7:14 PM Reply   
Thanks David and Brett.

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