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When more than 1 battery is needed


vlong

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I have an 05 LSV with a 4 channel 300w JBL GTO504 on the 4 tower speakers and a 4 channel 400w? GTO 75.4II on the boat and sub box. The amp with the sub and 4 boat speakers cuts out at higher volume so I'm thinking of using a 300w mono sub amp that I have to run the subs for now.

Current set up I can listen to music at various volumes for an hour or two with no issues. Will adding the sub amp require additional batteries? Eventually I wanted to add another deep cycle battery and perko switch in case I drained one jamming in the cove but after reading some posts here I am concerned about having enough power now.

When do I need more batteries?

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Im a fan of dual batteries in any boat. But to answer your question, the need for a second battery will be calculation of average current draw and how long you want to run the stereo with the engine off. With the engine running, a single battery and alternator is fine.

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We usually don't sit for more than an hour or so and the volume varies from low to 20% if we are floating behind the boat. After about 45 minutes I crank the boat and let I charge for a few. I agree with the dual battery for safety purposes and will eventually set that up before sitting in the cove for extended periods of time. I just wonder how much faster I will drain the batteries adding the 300w amp to the system. I just bought a new head unit and WS420 so I need to build the kitty up a little before doing the dual battery project.

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Two batteries in a boat is almost a must in my mind. Even if you don't use them as one large bank, at least you have a back up should something happen to the main battery. It's sure cheaper than a tow or a jump start if you have to pay for one. You could add battery complete with switch for about 200 bucks total.

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You should always have two batteries (or more), with a switch on any power boat, to always have that peace of mind that you can start the motor after listening to tunes in a cove somewhere. I have a starting battery, and a deep cycle on a Perko switch.

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Ok, I run my boat on river type lake with many friends so being stranded on the lake is not a concern at this point. Yes, I have always had 2 batteries for safety and will do that this summer, I guess I should have clarified this. Besides that, why else would I need 2 batteries for my system? I guess the right question would be, is there a threshold of "watts" worth of stereo equipment when I would need to go to grouped batteries or some of the other set ups I read about in these posts?

Edited by vlong
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As you know batteries are just a fuel tank of sorts. Not knowing how fuel efficient , and how hard you will run your system , it's difficult to know exactly how long your existing battery will last. Way too many variables there.

With 3 amps......you need another battery.

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Ok now we're getting somewhere. So when you say more battery capacity you mean the "grouped" battery setup? So I'm not planning on putting much more stereo equipment than what I have, so what would be an entry level set up for "more capacity" in case I need it. Sorry, I am pretty handy but haven't messed with battery systems much.

If your usage is such that you run your dedicated stereo bank down below 12.0 volts on more than the rare occasion then you need to add more battery capacity.

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You most like have a group 24 in there now. Adding another group 24 would be as entry level as you could get I guess. If your go through the effort to add one though, I would opt for a larger deep cycle. Group 27or 29.

You will need a few cables, you can buy these pre made if you like. A battery and proper sized box. Does your boat have a switch? Is it dual position? If not you will need a perko switch to select them.

If your lazy, you can just get a battery, box and cables. Tie positive to positive, negative to negative of each battery. Now you have a larger "fuel tank" per say.

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vlong,

As pointed out by BB above, there are more cost-effective routes than just adding additional group 24 batteries in parallel on the stereo bank. Besides, within the same bank you want to avoid mixing aged and new batteries. Ratings will differ from brand to brand. But to place an average on lead acid battery reserves, you could roughly expect ('group meaning size in this case)....

Group 24 = 65 A/Hs.

Group 27 = 85 A/Hs.

Group 29 = 95 A/Hs.

Group 31 = 105 A/Hs.

The cost increase for upgrading a group size is less than using multiples of smaller group sizes.

So yes, within the 'grouped' (multiples in parallel) on the 'dedicated' stereo bank side.

One larger size of battery, whether a group 29 or 31, will most likely get it done for your set up. However, that voltage measurement at the end of a rest period is the most objective reference you will have. If you discover that you are depleting the battery below the 12.0 V threshold then you want to discover this early in the battery's age and supplement it with an identical battery. In a month or two is okay. Adding to the bank after a season of use is not recommended.

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Ok, after researching I get the group now. So I have 1 group 29 battery and will add another this summer. If I use the perko they will not charge at the same time, correct? So would I need the "Blue Seas" switch with the automatic charging relay or is there a better set up?

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I would strongly consider replacing both batteries. When combined your new battery will only perform to the level that the old battery does.

When wired in Parallel / the weakest one dicates the performance for the entire bank.

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^^^^ Very True.

A standard dual battery switch is all you need. The Blue Sea relay/switch combo doesn't do anything additional that you can't manually do if you understand the different scenarios and needs. The kit just does it automatically and so conveniently. And the Blue Sea kit won't change the fact that you will have to be aware from time to time of how low you are typically discharging the stereo battery bank.

With the standard manual switch you control when both battery banks charge. With a moderate system and batteries that are depleted to a reasonable level you will always have the manual switch selected to 'ALL' (combined) when the engine is running. If the stereo bank is #2 for instance, then you will select #2 on the switch when at rest keeping the starting battery (#1) off line and in isolation.

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I highly recommend the blue seas kit. With it installed you rarely, if ever, have to crawl down and switch a battery. If you install the stereo system to only the stereo batteries and then have a starter battery which is separate the the blue seas switch will automatically charge the weakest one first. You don't turn any switches. Why make it hard on yourself, one less thing to fiddle with.

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I highly recommend the blue seas kit. With it installed you rarely, if ever, have to crawl down and switch a battery. If you install the stereo system to only the stereo batteries and then have a starter battery which is separate the the blue seas switch will automatically charge the weakest one first. You don't turn any switches. Why make it hard on yourself, one less thing to fiddle with.

Does the Blue Seas need the charger relay for the auto charge to work?

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Yes, the Blue Sea ACR (auto combining relay) is needed for that automatic function. Without the relay, its just a manual dual-battery switch. But just to clarify, the Blue Sea 7610 ACR, which is what comes with the popular "Add-A-Battery" kit, does not distribute on demand to the lowest battery first. It has a programmed hi and low voltage threshold and opens and closes bast on load and battery level. Its a 2 wire relay and it takes a 3 wire system to distribute on demand.

If you do go with just the manual dual-battery switch, The Blue Sea switch is much better then the Perko.

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Yes, the Blue Sea ACR (auto combining relay) is needed for that automatic function. Without the relay, its just a manual dual-battery switch. But just to clarify, the Blue Sea 7610 ACR, which is what comes with the popular "Add-A-Battery" kit, does not distribute on demand to the lowest battery first. It has a programmed hi and low voltage threshold and opens and closes bast on load and battery level. Its a 2 wire relay and it takes a 3 wire system to distribute on demand.

If you do go with just the manual dual-battery switch, The Blue Sea switch is much better then the Perko.

Yes, the Blue Sea ACR (auto combining relay) is needed for that automatic function. Without the relay, its just a manual dual-battery switch. But just to clarify, the Blue Sea 7610 ACR, which is what comes with the popular "Add-A-Battery" kit, does not distribute on demand to the lowest battery first. It has a programmed hi and low voltage threshold and opens and closes bast on load and battery level. Its a 2 wire relay and it takes a 3 wire system to distribute on demand.

If you do go with just the manual dual-battery switch, The Blue Sea switch is much better then the Perko.

So, I understand what you are saying but I'm trying to figure out when that would become an issue. If I use the add a battery, it would keep me from running down the start battery. If I ran the house battery down, I would then have to run the boat long enough to charge the house battery and then it would charge the start battery if I'm pickin' up what you're layin' down? I guess the question would be, how long does it take to charge the house battery back up then the start battery after the ACR switches over to charge it?

Also, is there a better ACR that is available that I need to think about?

Thanks for the info by the way...

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Vlong,

If I use the add a battery, it would keep me from running down the start battery

A simple dual-battery switch will allow you to isolate the main cranking from the stereo/house loads while at anchor, leaving it in reserve. But, you have to manual rotate the switch in order to apply alternator charge to each or both batteries. This is where the addition of an ACR/VSR come in. When the engine is running and the ACR senses the alternator voltage on side (A), the ACR closes and passes the alternator charge on to the house battery. So the ACR adds a level of automation the battery switch setup.

If I ran the house battery down, I would then have to run the boat long enough to charge the house battery and then it would charge the start battery

First, if you ran the house battery down, running the engine would not recharge it for a long time. Thats a whole new topic.

The charge from the alternator is always going to the main cranking battery, the ACR does not receive the alt feed first, the distribute on demand. Thats takes a processes controlled 3 terminal. Most ACR/VSR relays are much simpler. They have programmed open and close voltage threshold. When the house side is low, the relay opens and isolates the main cranking side. When voltage is up on the main side, it closes and passes alt feed to the house side.

I guess the question would be, how long does it take to charge the house battery back up then the start battery after the ACR switches over to charge it?

if we are talking a depleted house battery, then probably 8-10 hours with the engine above idle. Alternators make for poor battery chargers. You need an actual battery charger to recharge a dead battery. If the battery is not run until its dead, then about 10 seconds after the engine is restarted, the ACR will combine and supply alternator charge to the house bank.

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My dealer recommended the Charles Start Now. He said that the start now is different because the second battery is a backup only. The first battery always gets priority when charging, starting is used for house loads as well. My problem with both of them is I like to switch manually to ensure both batteries are being used and charged close to the same number of times. I don't like the idea of not having the same wear and tear on both batteries. In the end I just went with the manual switch, it's cheaper and I have used one for years on all my boats without having any problems. I've seen too many guys with fancy boats, battery set ups, and chargers being jumped or towed home. It's just an opinion and maybe I'm outdated but it's worked so far! Good luck I ordered my manual switch yesterday.

GP

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