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View Full Version : Lets's talk multiple battery setups. (3+)



dusty2221
01-03-2011, 10:06 AM
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. :)

Razzman
01-03-2011, 10:26 AM
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.

dusty2221
01-03-2011, 10:34 AM
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?

KG's Supra24
01-03-2011, 10:43 AM
Is there a spec or a way to know how efficient your amps run? I'm sure there is a formula for this?

Razzman
01-03-2011, 12:32 PM
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.

you da man
01-03-2011, 12:49 PM
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.

Brianinpdx
01-03-2011, 12:51 PM
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

EarmarkMarine
01-03-2011, 12:52 PM
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

dusty2221
01-03-2011, 01:01 PM
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?

EarmarkMarine
01-03-2011, 03:24 PM
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

zabooda
01-03-2011, 08:22 PM
The RV industry uses golf cart batteries with two 6 volts in series with Trojan T-145s kicking out 205 AH in a six hour period. They don't look like your grandpa's battery but they are made for non-starting loads but they weigh in at 71 pounds a piece. I use them in my RV where size and weight isn't a factor and they last twice as long as any marine battery. The Costco version costs about the same as the marine batteries.

http://lemley.net/electric/trojan.html

dusty2221
01-03-2011, 08:26 PM
I actually considered the 2 6v battery route as I have experience With them having had a cart in the past. So since its been brought up, can anyone elaborate on the pros and cons, side from the size, of going this route? also taking into consideration my existing dual bank charger, and charging all 3?

mmandley
01-03-2011, 09:09 PM
Con would be the alternator and entire boat is a 12V system.

Wouldn't you have to wire those batteries to be 12V outputs some how because nothing on the boat will work other wise.

MLA
01-03-2011, 09:21 PM
Con would be the alternator and entire boat is a 12V system.

Wouldn't you have to wire those batteries to be 12V outputs some how because nothing on the boat will work other wise.

It takes 2 6V batteries wired in series to get the needed 12V's, so if someone goes the GC battery route, they will need to be done in pairs.

EarmarkMarine
01-03-2011, 09:21 PM
You would only use two of the 6 volt models in series for the stereo bank which would equal 12 volts. The starting battery could be a conventional marine Group 24 12-volt lead acid.
The only reason to avoid golf cart batteries is if you have already had a history of back problems.
Depleted amp/hour capacity will be the same issue relating to the alternator and shore charger load as with any other batteries of the same capacity.
The dimensions are a consideration. Golf cart batteries certainly are a great amp/hour per dollar value.

David
Earmark Marine

dusty2221
01-03-2011, 10:05 PM
And with these 2 6v cart batteries wired in series, to act as one 12v battery, regarding charging, the second bank on my charger would be coinnected to the + or 6v batt 1 and the - of 6v batt 2. Correct? This would then charge the batteries equally? And with this method, I just increased my amp/hour with 2 6v over the 2 12v accesory batts and made a true "dual" 12v setup for the charger to work as designed?

I mean, am I missing something, or am I appropriate in wondering why on earth people would go with 2 12v batteries for accesory with lets say a 115 amp hour rating each when they could use 2 6v batts rated at approx 205 amp hours each?

I feel like the dual 6v in series makes more sense and is so simple it's brilliant, however, David, I have seen several of your installs and have seen no trace of 6v batts. Which makes me wonder what I am overlooking.

EarmarkMarine
01-03-2011, 10:19 PM
In a series configuration you don't sum the amp/hours as you would in a parallel configuration.
We don't like handling the extra bulk and different dimensions on an everyday basis. But don't let that influence you as I really don't have any reason to discourage the use of GC batteries.

David
Earmark Marine

dusty2221
01-03-2011, 10:45 PM
Ah, so for simplicity sake, and for black and white:

1) 2 6v batts rated at 205 amp hours each will provide only 205 amp hours total once wired in series?

2) 2 12v batts rated at 115 amp hours each will provide 230 amp hours total once wired in parrallel?

Is that correct?

MLA
01-03-2011, 11:11 PM
Ah, so for simplicity sake, and for black and white:

1) 2 6v batts rated at 205 amp hours each will provide only 205 amp hours total once wired in series?

2) 2 12v batts rated at 115 amp hours each will provide 230 amp hours total once wired in parrallel?

Is that correct?

Correct.

Like David said, 6V GC's are not a bad way to go, but not always the best. Its sometimes hard to beat a pair of plain old marine deep-cycles for their Ah V's $$$ bang for your buck.

dusty2221
01-04-2011, 11:03 AM
Just to keep this topic fresh, I've been reading a bit more about a dual 6v set up this morning.

Taken from this link: http://www.marxrv.com/12volt/12volt.htm


A lot of RVers have switched from the "standard" group 24 or 27 12 volt batteries to the larger 6 volt golf cart batteries. If you have room for at least 2 of them, they are a good choice. They are true deep cycle batteries and will last a lot longer than most common 12 volt batteries in your RV. They are physically larger, so you must measure carefully before buying them, but I recommend you use them if you can. I have a set of Trojan Golf cart batteries that are going on 5 years old and they still have almost all of their original capacity. They are priced about the same as (or a bit lower than) the common 12 volt deep cycle battery. Golf cart batteries have a higher capacity than group 24 and 27 batteries... a pair of group 24 12 volt batteries only provide 140-170 amp/hours of capacity, where a pair of golf cart batteries provide 180-220 amp/hours. There are other deep cycle batteries available, such as the L-16 and AGM types, that are extensively used in large solar and alternate energy systems, but their physical size and added expense make them a less attractive choice for the average RVer.

Now given, I realize this is referencing an RV application, but the same theories apply. I'm coming to conclusion that amp/hours can't be argued, and 2 6v are simply the better way to go (size permiting).

I guess my next step is to call ProMariner directly and confirm with them that my ProSport 12 charger will meet this application and will charge my Crank battery as well as the dual 6v.

The site above has tons of useful battery info, good read regardless of what you intended use is.

Thoughts?

cab13367
01-04-2011, 11:57 AM
I'm coming to conclusion that amp/hours can't be argued, and 2 6v are simply the better way to go (size permiting).

How so? You quoted that a pair of 6V golf cart batteries provide 180-220 AH whereas a pair of Group 27 marine deep cycle batteries provide 230 AH (at least the ones at costco do). And they are smaller than the 6V batts.

Also, I think you are going to have to upgrade to the ProSport 20. As David has pointed out, you need a charger with an output of 10-13% of your total battery AH in order to desulfate the batteries during charging.

I currently have a two battery set up (one starting and one stereo) but fortunately, I bought the ProSport 20 in case I added a third battery in the future. Sure enough, I went from two amps to three at the end of last season so I am going to add a second stereo battery this winter. With that, my charger will be below the 10-13% recommended output for the 230AH worth of stereo batteries (not even counting the starting battery) but as long as I don't discharge them too deeply, I think I will be okay. At David's suggestion, I will probably add a switch to the starting battery charger lead so I can take it off line when needed and direct all 20 amps to the stereo bank.

Al

cab13367
01-04-2011, 12:05 PM
FYI, below is a shot of my current two battery set up.

http://i250.photobucket.com/albums/gg276/cab13367/Boat%20Pics/IMG_07592.jpg

And here is a better shot of my Blue Sea ACR set up, before I added the on board charger and the third amp.

http://i250.photobucket.com/albums/gg276/cab13367/IMG_6511.jpg

dusty2221
01-04-2011, 12:11 PM
How so? You quoted that a pair of 6V golf cart batteries provide 180-220 AH whereas a pair of Group 27 marine deep cycle batteries provide 230 AH (at least the ones at costco do). And they are smaller than the 6V batts.

Also, I think you are going to have to upgrade to the ProSport 20. As David has pointed out, you need a charger with an output of 10-13% of your total battery AH in order to desulfate the batteries during charging.

I currently have a two battery set up (one starting and one stereo) but fortunately, I bought the ProSport 20 in case I added a third battery in the future. Sure enough, I went from two amps to three at the end of last season so I am going to add a second stereo battery this winter. With that, my charger will be below the 10-13% recommended output for the 230AH worth of stereo batteries (not even counting the starting battery) but as long as I don't discharge them too deeply, I think I will be okay. At David's suggestion, I will probably add a switch to the starting battery charger lead so I can take it off line when needed and direct all 20 amps to the stereo bank.

Al


Well, I guess i was basing that assumption on what the quote I added showed. I must have breezed past the 12v rating you mentioned, or read and and didn't "read" it. Ha

As far as the 10-13% recommended output, does the fact that the charger would have a lower output than that really make a difference in charging aside from a longer charge time? So rather than my Pro12 charging the 2 current (1 crank, 1 stereo) in say 6 hours, if hooked to 3 as mentioned earlier, it would still charge, however, the time it took would greatly increase if they were completely depleted, but they would be charged, conditioned and maintained properly?

I hope all that makes sense.

Also, I am taking it as you have the Pro20 dual bank rather than the 3 bank?

cab13367
01-04-2011, 12:18 PM
Well, I guess i was basing that assumption on what the quote I added showed. I must have breezed past the 12v rating you mentioned, or read and and didn't "read" it. Ha

As far as the 10-13% recommended output, does the fact that the charger would have a lower output than that really make a difference in charging aside from a longer charge time? So rather than my Pro12 charging the 2 current (1 crank, 1 stereo) in say 6 hours, if hooked to 3 as mentioned earlier, it would still charge, however, the time it took would greatly increase if they were completely depleted, but they would be charged, conditioned and maintained properly?

I hope all that makes sense.

Also, I am taking it as you have the Pro20 dual bank rather than the 3 bank?

I will try to do justice to David's explanation on the importance of having adequate current when charging batteries. A certain amoun of current (10-13% of the AH rating of the battery) is needed to chemically excite the batteries so that all the sulfates that stick to the lead plates when a battery dischages releases from the plates and goes back to the acid solution. If you don't have enough current, the sulfates will stick permanently to the lead plates and over time, your battery will have less and less reserve capacity.

Yes, I have the dual bank 20. The 3 bank is still 20 amps and since the two stereo batteries will be wired together as one bank, only a two bank charger is required.

dusty2221
01-04-2011, 12:53 PM
Got it. Thanks.

So what we just boiled this whole thread down to is this:

1. 2 12v for stereo is an easier setup to work with, and with the costco batts will provide more a/h than the 2 6v

2. The Prosport12 will not excite 3 batteries if depleted badly enough

Conclusion: Like anything boat related, (ha) My simple quest to add 1 battery has now turned into

1. Two new 12v deep cycle batteries (on Davids recommendation on same age etc)
2. A new Higher output Charger, or different setup of existing, which there are three options for:
a) The Pro20 with a switch inline to bank one(starting) for dedicating the full 20 Capability of the Pro20a to the two stereo batts for those recharges after a long stereo day
b) A dual bank 30a charger, like the Guest 2633A that offers one bank with a 20a output and the second as a 10a output
c) Move existing Pro12 exclusively to the dual stereo batts and get a basic 1 bank charger for the house batt. Although, this route doesn't supply the needed amps in case of complete depletion and could end up allowing the lifespan to shorten since the 2 batts would only be getting a combined 12a

Have I narrowed it down to what you would agree with?

EarmarkMarine
01-04-2011, 01:47 PM
Dusty, you can easily recover your investment in the ProSport, probably from someone on this forum who is in need.
Get an Intelli-Power 30 amp charger and a flushmount AC inlet that can be installed under the hatch next to the engine. This way all you have to do is fold back the cover and raise the hatch while standing on the trailer. You won't have to climb into the boat. The Intelli-Power 3-bank will function as a dual bank with two stereo batteries permanently wired in parallel or you can wire it as a 2-bank plus this charger has the ability to distribute its capacity based on the bank that is in need.

David
Earmark Marine

KG's Supra24
01-04-2011, 01:56 PM
Or it is possible all of this is over thought out and you are fine with the 2 batteries you currently have bc I ran 4 amps all last year and had no issues. :D

just thought for simplicity sake. And if the battery goes dead then you have $$ you saved from not buying everything else discussed in above threads

GO HOGS!

dusty2221
01-04-2011, 01:58 PM
Anything worth doing is worth over doing. :)

sandm
01-04-2011, 02:43 PM
I think that every answer about this is going to be different. if your boat is in the party cove every weekend for hours on end, tons of led's that get used longterm every night and you hate digging into the batteries after every outing, then the charger and extra batteries would be something to highly consider. I have found that with a moderate system, 2 good deep cycle batteries, and occasional long play usage at moderate volume levels, the 2 battery system is good enough, and the onboard charger is really more of a convenience than a necessity(same thoughts as KG I believe) :)

do the research, put in what fits your needs and don't follow the sheep..

cab13367
01-04-2011, 04:02 PM
sandm is correct - every situation is different. In my case, I started it out with two amps and two batteries (one stereo and one starting). Everything was fine until I went on a 4 day trip where I had no access to a power source. By the end of the second day, one of my amps went into protect because the stereo battery had run down (we do a fair amount of swimming and listening to tunes as I have a couple young kids). So we had no tunes for the next two days.

I did some research on battery chargers and decide I wanted an on board charger for the convenience of being to just plug it in when I get home every night and be assured that both batteries will be desulfated and ready to go the next time. Got good advise from David so went with the ProSport 20.

Now I've added a third amp and my system is now capable of 2050W RMS and for me, adding a second stereo battery is a relatively low investment - basically $69 for the batt, maybe $12 for a batt box, and a few dollars for short runs of cable. Also, my tow vehicle battery crapped out this winter so I threw the stereo battery in the truck as it was the right size, and since you should always start with two equal batteries when setting them up as a single bank, this is the perfect opportunity to upgrade to two stereo batts so I don't ever had to worry about running out of juice on the water again.

So that's how I got from point A to point B to point C.

Al

zabooda
01-04-2011, 05:28 PM
And I only use the one battery and keep the weight out of the boat for skiing. I bought the boat in 2002 and I time the stereo usage. I now carry jumper cables as I did replace a 500 watt subwoofer amp with a 1000 watt amp. The cables are used for the varibles like the stereo left on too long or the battery deteriorating. I go two hours and then I am forced to go run the boat or turn the stereo off. I have yet to use the cables.

It appears weight is no factor with the bigger boats so having the isolation is a real plus. For a system of 3+ batteries, I have been sold for many years with the golf cart batteries in my motorhome where I run without AC power for eight days at a time. I went through deep cycle batteries much faster and that may be the way I ran those batteries down. I now find the Trojan batteries jumped in price a few years back where the Costco GC batteries made by Johnson Controls works as well for the price. To each is their own style and assurances. I live on the fringe and I hate replacing batteries and tires that die from age rather than from useage.