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Battery help

Derrick, I like the JP Magazine battery tests that your link points to, the Northstar batteries really shine there. And I suppose buying Canadian has a strong appeal to you as well, so no more flooded battery suggestions from me. I will however ask if you have thought about mixing battery group sizes. What I have found is that the starting battery pretty much stays topped off all the time - after a brief draw when starting the engine, that battery is recharged within minutes. The draw on the house system on the other hand could easily over-run the amps available for recharge from the alternator (50A on the Verado, right?), at least with that monster stereo you have planned. So why not drop to a group 24 Northstar for starting, and move up to a group 31 for House (I suspect you don't have space for an 8D). This would give you extra capacity where you need it, and still leave more than enough resources for starting.*

*The Blue Sea Systems 7610 ACR normally combines banks when a charging system is present, but will isolate the banks when discharge exceeds the charge present. (It actually starts cycling open/close in a loop - it will combine, sense the discharge, isolate, after a time sense a charging source, combine and so on.) The end result is that it is possible to deplete a house bank while the engine is running, even with an ACR, if the load or discharge rate exceeds the amps available for charging. One can place a toggle switch on the ground to the ACR to manually turn it off (isolate), and once the heavy load from the jam session is over, turn it back on to allow combining.
 
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That's not a bad idea about the 2 group sizes, I'll have to check. As for the second part of your post, ya totally lost me!! Haha
 
My 7610 doesn't do that. It works off voltage level, not current drain. When the batteries are charging, the terminal voltage is boosted to 14+ volts (it has to be greater than the battery's normal voltage or you won't push current into the battery). Then, when you turn the motor off and the charging system is off, the battery voltage drops to 12 volts (technically, it's higher, but just making the point that it is less than the voltage when the charging system is active), and the relay isolates the batteries.

After thinking about it more, maybe I see what you are saying. If discharge current is greater than the charging current, the voltage would drop due to that, and thus cause the relay to isolate the batteries. At that instant, the starting battery voltage would suddenly jump up to 14+, causing the relay to reconnect, and thus the endless loop...

Interesting problem. In my situation, I'm never drawing more current than the charging system can provide, therefore I don't see this problem. Back to the manual switch for that situation, I guess...
 
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Hmmm, I think I am starting to understand your theory Jim. That is a dandy question to ask, now I just need to figure out who I think will know the answer. I'll have to look on Blue Sea's website.

I was going to call my dealer today and see if he could scrap the switch on my order because I planned on buying the add a battery like Tom, was even going to say Benny should really update their builds to this system, but now I wonder. The worst thing about trying to figure this out is trying to think of who would actually know the answer. I'm leaning towards a 3 battery setup, a 24 for starting and 2 31's in parallel for the house. This also leads me into another dilemma, charging.

So I understand that the starting battery is 1 bank, and the two batteries wired in parallel are also classified as 1 bank. So I could get a 2 bank charger and it should work right? But here is the funny part, the shore chargers all talk about being 'smart' and taking care of everything to do with the batts, it senses their condition and applies the proper charging procedure based on that. But what about when in parallel? And, when I was originally talking to the fella at the battery place and was looking at a 24 and a 31, he told me I could get a 3 bank charger, have 1 on the 24 and put 2 banks on the 31 to feed it 20A of juice. This sounded funny to me, once again basing it on the 'smart' charger idea. Now, if I COULD do that, then I could still buy a 3 bank charger a hook 1 bank to the 24, 1 to the 31 and 1 to the other 31, while still being in a parallel state. But it seems funny to me, so once again, I ask for knowledge, or at least good guesses!
 
Derrick,

The answer can be 'backed into' by looking at the total draw from the 3 amps, and estimating desired 'play time'. As Kaydano pointed out earlier, the ACR senses and reacts to differences in voltages, but for me it is more intuitive thinking about the draw or charge source in terms of amps. Sans the three amplifier stereo, your new boat would do fine with a single battery, perhaps if you tell us the watts of each amp we can ballpark the total draw and back into an appropriate desired battery reserve capacity.

On the subject of chargers, no question that dual or triple bank smart chargers are nice, but they don't play well with ACR combiners. The combiner senses the charging source and would combine banks defeating the advantages of dual bank charging. Again, all that needs to be done is to install a toggle switch on the ground wire to the ACR to turn off the ACR prior to enabling the multi bank charger. I have this setup on my bow rider. In fact Blue Sea Systems manufactures a panel with such a toggle switch nicely silk screened, for this very purpose. With the ACR off, banks won't be combined and the smart charger would for example be able to discern that the starting battery is topped off and can float, while the house bank needs bulk charging. As to sizing of the smart charger, I think I read that Northstar recommends a maximum of 10 amps per bank for shore power constant voltage chargers. Even if you went with a two battery house bank, I think a two bank battery charger would meet your needs as in effect the two batteries in the house bank would act as one battery (IMHO) and the smart charger would treat them as one bank. The only limiting factors are the amount of amps that the charger can provide, and the amount of time available for recharging before next use. If time or available amps are not enough to provide a full recharge before the next outing, perhaps a three bank charger could be looked at, but you'd need a way of separating the two batteries in the house bank ( another switch).
 
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Okay, here are the amp watts, one amp will run the towers, 400w x 2, one amp will run 6.5's 125w x 2 and 100w x 4, the powered sub 500w x 1, and there is a good possibility of 2 more subs running 1000w between them. So all together, just shy of 3000 watts of juice. I was thinking about the ACR toggle switch you mentioned, and wondered if that was also the answer to my parallel problem? If I put in a switch to essentially "disconnect" the parallel configuration of the 31's then a 3 bank charger would be used and it could keep each battery optimized at its fullest potential, assuming I also did the previously mentioned toggle on the ACR. So that may solve the shore power charging, but what about the while motor running issue of the ACR if the stereo is booming will it be cycling between combined and isolated and cause issues?

You must be a better researcher than me, I don't remember seeing the charge amps the Northstar likes, I will dig now since I was looking also at the Professional Series of Gerry's charger and it's 15A per bank!

I'm wondering if I should stick with the regular installed switch from Bennington and just be aware of my duties for the batteries and switch position. I could also add a battery voltage reader and keep my eye on it, although I suppose with the upgraded Garmin, pretty sure it shows the voltage on the screen!

Thanks again Jim, I REALLY APPRECIATE it! Good things can come from ideas and theories being tossed around. Interested in what kind of amp draw you figure it could POTENTIALLY be pulling.
 
Sorry been a bit distracted with 'Long weekend' activities. If I remember the formula correctly, one would take the 3000 Watts divide it by the voltage, 12V, and the result would be 250 Amps. Yikes! 5 times the total output of your alternator. :eek: Of course, I doubt you will run with the volume up all of the way much, but in theory it should be pretty easy for you to overrun the output from your alternator. Makes me think that one of those old analog voltage gauges that swing up towards 14V when the alternator is providing a charge, and down towards 12V when you start running on battery might be good to have. Then if one saw the needle swing down, one could turn down the volume, or switch off the ACR (to avoid the on/off switching loop discussed previously) and run solely off the house bank.

So if I am following correctly, you are now looking at a bank of two Group 31 batteries for your house bank. With 2 Northstar Group 31 batteries in parallel, one would have a theoretical Reserve Capacity of 2 x 205 minutes or 410 minutes at 25 amps. Reserve capacity in minutes drops drastically given large increases in amp draw, so one could easily conclude that with a draw of 250 amps, one would have a lot less capacity than 41 minutes. I think I saw a chart somewhere that would graphically depict running time at different loads. I’ll dig around some tomorrow. Might help to back into how long you could run at varying volume levels. To my mind the only way to know for certain is to start a timer and crank the volume!
 
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Thanks Jim, that was the amperage I came up with too, which is the obvious reason I'm concerned with the batteries, and having GOOD ones!! I sure can't see me finding a spot to put another battery! Not to mention the cost. I'm starting to think I should have just left the stereo alone! Haha although when I first get it I won't have the 2 additional subs, I'll have to save some cash plus make sure everything else is suitable. Thanks again,

Derrick
 
Ok, found the graph I was looking for over at http://www.pureenerg...zel-battery.pdf Some really good info there, but the graph didn't really apply to the theoretical situation at hand, instead it shows available capacity at different draw rates up to 50A for 120AH batteries of different Peukerts equation rates. Essentially Puekerts equation accounts for draw down, and different types of batteries draw down at different rates. The Northstar AGM, I'm assuming, will come in with a Peukerts value of 1.08 (at the top of the chart at the link). Which is really good. Extending this analysis to your theoretical 250A load and two Group 31 Northstar AGM batteries using the 1.08 value, you would be able to run a 250 Amp load for about 50 minutes. After 50 minutes at 3000 Watts, you probably wouldn't have much hearing left anyway. :lol:
 
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Thanks Jim, I don't plan on cranking the stereo for long periods of time, of course when my Raise Your Weapon - Deadmau5 comes on the playlist it might get a little extra bump!! I'm trying to figure out the best way for these switches. i think I'm going to use the Wet Sounds Wet Wire, it's supposed to be the best. And they make a handy 4 amp wiring kit.
 
Off topic, but if you like that, I'd suggest You're Early by 2:54, or Oblivion or even Circumambient by Grimes.
 
Hey Jim, and anyone else electrically knowledgeable, I have a wiring diagram that I got using the Blue seas product, was told this is how the folks with monster stereos wire it up, I'll try to post in the gallery.
 


Here it is, make sense?
 
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Interesting. Instead of the traditional House/Starter configuration, they show a Stereo/Everything else configuration. I do think that in place of the 10 Amp fuse on the ground from the ACR, a switch should be installed. The switch should be off when using the dual bank charger, or when loads exceed the alternator output. I suppose that they assume one would turn the Add a Battery switch to off when charging with a dual bank charger. It is my understanding that the start solution wire is not needed in this configuration. Also, the ground wires would not go to engine block with an outboard, instead they would both connect to the ground post where the negative lead from the outboard connects. I believe there should be fuses placed within 6 inches of each battery on the 4AWG or larger runs to the switch especially if those wires are longer than a couple feet. I would wire the LED and ground connection from the 7610 ACR to the Everything else battery, just seems cleaner to me.
 
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My cousin is the one that gave it to me, it was shown to him when he was doing his boat. He actually has 6 batteries, the 2 "factory" run the starter and house and he has 4 group 31's for the stereo. That's a lot of lead. So what are your thoughts on it? How is this setup better than something else like the wiring blue seas shows on their site?
 
Derrick - It occurred to me that you could figure out how many amps your system will use by installing a series of fast-blow fuses, one at a time, starting with a small fuse (say, 2A) and work your way up in fuse rating until it doesn't blow at the sound levels you want, then you could back-calculate how much power your system is really using and how much battery power you REALLY need to run your system.

In my opinion, adding up nameplate ratings will FAR overstate your actual use. I think Jim mentioned that, I don't know, I scanned through all the posts too quickly.

On the other hand, I have a couple old NAD amps (80s vintage). One is rated 40 Watts per channel. But that is a continuous rating based on a continuous test tone. Music is FAR from being a continuous tone, and the 40W amp will put out 260 Watts for a very short duration (to cover a drum beat, for example). In terms of "music" power, it blew away a 100 watt amp I had because the 100W amp didn't have the headroom the NAD had. The 100W amp peaked at 100W, where the NAD, with 6 dB of headroom, could output the full 260W, it just couldn't do that continuously (it could hit 260 Watts for short duration bursts, then the amp recovers quickly for the next burst/drumbeat). Headroom measures how far above the continuous test tone an amp will put out in terms of "music" power and this better represents reality (in that music isn't continuous but rather it is variable, and thus the power demand from the amp varies). I guess I just contradicted what I just said above about not exceeding nameplate ratings...

Anyway, this is even more reason to plug and chug fuses until you get to one that won't blow. That will tell you your max usage. You could also try slow-blow fuses to see if your average use is very much lower than your peak use. If it was me, I would use the average power to figure out how much battery power you need.
 
Oh, I absolutely agree to a point. I know that I doubt I will EVER have it at max volume for any period of time, but if you prepare for the worst, you can end up with the best. I'm trying to figure this out so I don't end up with an issue later on. Hey, new slogan, "Buy it once, Buy it right, Bennington. " maybe I shouldn't be the spokesperson for that one. In the beginning I won't even have one of the amps hooked up, the SYN1. I just simply don't think I can afford the subs to go with it. But I figure I should plan the power plant so that hopefully by the end of summer or spring, it will be ready and I won't HAVE to change anything. That's not to say that I won't, but I don't want to have to. Also, Wet Sounds products are said to run extremely clean, meaning they can draw less power and have more output. Don't know the details, but it sure sounds good! Haha I believe it would be an audiophile's system of choice, for a boat. Especially after hearing it first hand. Check out their new Sinister series, the power output is incredible. What really means something to me is you get a guy like me, who as you know asks MANY weird and off the wall questions, and you get a guy like Tim at Wet Sounds who is passionate about his company and answers constantly, and promptly. I like companies that are 100% behind their products, and strive to show it. That's why I chose Bennington, and that's why I want this Wet Sounds system to work great, on my fairly limited budget! I think this battery setup should work ok. I know the math is there and what it suggests, and I know that is with everything maxxed. I was talking to my cousin and he has a much bigger system then I am compiling and although he has 4 batteries, told me they sat there at the dock with the music going pretty decently for 4-5 hours without issue, so I suspect I should be okay, now I just need to figure out the best way to hook them up and get them charged. He uses a Xantrex 40a charger, I'll have to get the model number off him so I can compare. Keep the replies coming, ideas and thoughts are always welcome! Thanks
 
Derrick,

This looks pretty good to me. Sorry I haven't kept up with your posts on this as I was hoping to help. I finally had to put my faithful dog down today so I'm a bit out of touch.

One thing I've discovered is a big cost factor is making sure that if you're future proofing and maybe doing it in phases, make sure that the wiring from the battery areas to the helm are there. I considered adding subs etc but getting 6 or 8 gauge from there to my helm without popping off the shields is nearly impossible. A proper conduit would be really nice.

Tom
 
I dread the day when I have to do the same Tom, my deepest sympathy. We don't have kids, just two big dogs and I get physically ill when one of them is hurt. I couldn't imagine it with a child, I'd probably have to be admitted. I appreciate you taking the time to chime in. I guess my biggest question now is how is the schematic above better than the one from blue seas, how is it different, and is it better than just switching the factory switch.
 
I guess the only thing I struggle with is connecting ANY house loads to the starting battery. I want it to always be there ready to fire up the motor. I could care less if the gauges or lights work at that point, unless of course it's at night.
 
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