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triscadek

Amos to perko or battery?

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triscadek

So I'm running 3 Amps, 1-1200w mono and 2-1000w 4ch for cabin and tower speakers. I ran 1/0 Welding cable (good for 300amps continuous up to 100') to a 1 into 3 dist block for the Amps. My question is, am I better to hook the amp wire straight to the battery and just letting the power remote wire kick them on or let the whole thing run through the perko? It's rated for 250 continuous and 360 intermittent.... Just don't want to be running too much throug the perko. I'm also running 2-180watt LED light bars on top of the regular boat electronics through the perko.

Thanks, Cale

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David

Run all components through the Perko.

Music is AC content so you will never pull close to 250 DC amps even with 3000 to 4000 total amplifier watts.

The Perko normally passes all charging and starting currents so there is no reason to bypass it for the amplifiers.

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TallRedRider

I'm a freak because of so many threads that pop up here from time to time about noise introduced into a system. The cure for that is to run ALL of the stereo's grounds and power leads to the same precise spot. That helps to eliminate alternator noise and other hisses and buzzing that might happen. The grounds are probably a bigger issue than the power, but nonetheless, I choose to put it all directly to the battery to never have any question. But I can do that because of the way I use the boat. The vast majority of my trips to the lake are short trips for a few hours and then back home.

It depends on how you use your boat. I have my boat always garaged except for days when I am houseboating and obviously using the boat every day. I also have an onboard charger that I use. I connect my stereo electronics straight to one of the batteries, and do not get any noise issues, but it is critical that the owner of the boat understand how it is wired. I put all of my stereo to battery #2. If I put the switch on 1, and then play the stereo all day, battery 2 does not get recharged at all because the alternatory feed is going to battery 1. That is not a big deal for me as I can then go home and plug her in to recharge the battery that has gotten depleted. Because most of my trips are short trips to the lake, depleted stereo battery is never an issue. If the switch is on both or 2, then the alternator recharges the batteries as I go. It is also important to know that there is a tiny amp draw at all times. If you keep your boat on a lift with no charger, having the amps straight to your battery will eventually take them out, although it should take weeks or longer.

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triscadek

Hmmm decisions... Usually the boat is used for long days and into the night boating/beaching. It is stored in a storage unit with electric 13 miles from the house. I am running 2 - 27 deep cycles tied together for the amps as battery number 2 (given the quantity) and a normal car battery just to start the boat in depleted situations. No amps or other stuff will be wired into the backup battery if I choose to run everything through the perko. I like the idea of killing all the power for a week at a time while in storage.

How big of a fuse do I need at the batteries with 3200 (max) watts. 2 amps are 1000w and I forget the class they're in but they're supposed to be 66% so really I'm sure they're only pushing like 660w each. The sub amp I'm pretty sure is a class A and supposed to be 90% and it's a 1200w 1ohm mono.

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David

triscadek,

Your amplifier could have a Class A input & processing section but it is unlikely that it makes power in Class A mode. Class A is horribly inefficient and not used in marine. RF states Class AD but it's just plain D.

Master fusing should be the collective sum, and no more, of all the fusing recommendations of the three amplifiers. Fusing is not an indication of the typical draw or the max draw, rather a value to protect the amplifier in case something catastrophic happens. It's unlikely something catastrophic would happen to three amplifiers simultaneously. So a value somewhat less than the collective sum is usually fine. You cannot determine fusing based purely on the power output. If your amplifiers are not externally fused then consult their manuals. The master fuse is to protect the boat and occupants in the event of an accident or major non-audio event. It's related to the draw, cable gauge and cable length. It will require more than the fuse rating to blow the fuse instantly. Guessing, a master 200 amp fuse should be more than adequate.

By running everything through the Perko battery switch, you are using it as it was intended, and a dual battery selection conflict resulting in noise is made impossible. It doesn't guarantee that there aren't other issues but it completely eliminates at least one potential cause.

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triscadek

Ok...

I think I misspoke, the Fosgate is a class D I believe lol.

The 2 - 1000w amps have leads coming out of the amp (marinized) and they each have an in line fuse. The one 1200w Fosgate amp does not have this but I have it hooked to a 60a that I had laying around. This is all under the dash, I'd like to have a fuse at the batteries also to protect incase of something happening within the 20' of 0 gauge from the batteries to the amps. When it comes to stuff blowing up or catching fire, especially on the water, possibly at night, I try to take extra precautions.

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triscadek

Our lake "can" be pretty rough in certain places, thus creating a lot of turbulence sometimes. I try to keep that nonsense to a minimum.

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MLA
I'd like to have a fuse at the batteries also to protect incase of something happening within the 20' of 0 gauge from the batteries to the amps.

Thats the master fuse david is describing. Its a must. You need circuit protection that will carry the potential load, yet not exceed the capacity of the cable.

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triscadek

The cable will take 300 continuos amps at 100' lol. Just trying to figure out about the max for what the amps will draw and go just be there or go a tad over.

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MLA

Ok...

I think I misspoke, the Fosgate is a class D I believe lol.

The 2 - 1000w amps have leads coming out of the amp (marinized) and they each have an in line fuse. The one 1200w Fosgate amp does not have this

The cable will take 300 continuos amps at 100' lol. Just trying to figure out about the max for what the amps will draw and go just be there or go a tad over.

What is the value of the two inline fuses? The Fosgate likely has chassis mounted fuses, what is their sum? If not, loot at the manual to see what fuse value R/F suggests. Add them up.

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triscadek

Each of the 1000w have a 40 amp fuse built in.

The RF manual says 150a for inline battery fuse. So I imagine a 250a will suffice. I have one here in the shop already.

Edited by triscadek

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DarkSide

IF you have a true 4000 watt system at 13v you would draw roughly 400 amps. IF you are at max volume. Here is the math.

Assuming Amp efficiency 80%.

Wattage is = voltage*amperage (ohms law) so 4000W/13v = 308 amps.

This is where it gets confusing, you only use max wattage at max volume. Your 1000w amp is only putting out 20 watts at minimal volume. Power goes up as volume goes up. Just like you're 450 engine does not put out 450 HP constantly, it can but only at full throttle. Amps work the same way. This is also why a higher powered amp gives the illusion of sounding better. It reaches x power faster than the lower rated amp. Example if you listen at 50% volume. A 300 w amp is pushing 150 watts a 500 w amp would be pushing 250 and thus driving speakers harder and producing more sound. However the 300 w amp would sound the same at 85% volume. Most of us like things to escalate ay different rates so we over power tower speakers and subwoofers to achieve this ballance. Rarely will any of us listen at 100% volume. Which is the only time you will reach full power.

With all that said if you run 4000 watts at full volume you absolutely will exceed the 250 amp Perko.

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MLA

Only one little problem with the above equation. That 4000W is in AC and the 13v and 400A are in DC. Cant apply ohms law using different forms of electricity.

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DarkSide

Granted music is dynamic, not really AC either. But yeah actually you can apply Ohms law, as a best case scenario. Reason being in that scenario, you would be inverting from DC to AC, as you lose efficiency at any conversion, my simple explanation is actually LIGHT. Pure and simply you cannot, output more power than you consume! Which is why amplifiers have an efficiency rating. A really efficient amp will be close to 80% so it will use 500 Watts of DC power to generate 400 Watts of AC "music" power. you absolutely cannot generate more music power than you consume from the batteries DC power.

Edited by DarkSide

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MLA

Music is AC and you cannot apply ohms law with one value of the equation is in DC and the other is in AC. I seriously doubt the OPs system will even pull more than 150A DC on average, and never peak above 200A DC.

I do agree with part of your statements. Amps do not "make" power, they simply convert it one form to another and this is why you can not strictly apply Ohm's law. Yes, amps are not 100% efficient, more like close to 90% with some these days.

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David

Quote, "....so it will use 500 Watts of DC power to generate 400 Watts of AC "music" power."

That's not accurate in any respect.

Look at a graphic representation of dynamic music, a graphic representation of an AC sine wave, and a graphic representation of DC voltage. The three have nothing in common and the equations to quantify each of these power levels have nothing in common.

You could accurate say, "At 80% efficiency it will take 500 watts of DC power to generate 400 watts of DC power."

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