Boat System questions

[anb.osu]

Hey all,

Bear with me on this as I have several questions that I have tried to get answered from others with moderate success.

I am installing a system in my boat. The boat is an I/O 5.7L, (basically a 350 chevy motor)

I already have a head unit and two speakers and have been planning on adding up to four more speakers km620's, and two skm10's subs.

I have now started to worry about power consumption because a lot of the time music is needed while beached, or floating without the motor running (so off of the battery) I have a PLMRA620 amp

http://www.pyleaudio.com/manuals/PLMRA620.pdf

see link for specifics, but it is a 2000w 6 channel amp, if I go with the six speaker two sub configuration then the amp will power four of the six speakers and the subs, and the head unit would power the front two. The other way the amp would just do the two speakers and the two subs....

I don't want to have to spend mega bucks on a deep cycle battery, but I would ideally like to be able to run the stereo for at least an hour without issues. I plan to add a second battery dedicated to the stereo.

1. What kind of play time should I expect, and if I want longer play time should I dial back the numer of speakers, say two speakers and one sub on the amp and then the two from the head unit. (I want some thump, but I don really need to be killin it, I just got two because of symetry more than anything)

2. When grounding the amp, I don't have a chassis ground, and have been told just to ground back to the battery..... any issues with this... (BAttery is only about 4 ft from amp)

Thanks for any help, and I am sure i will have some folllow up questions so bear with me.....

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Click to read more...

 

[SeaNile 10+ year member]

Best bet is to post on the site http://www.thehulltruth.com

It's a great boating site and many guys have installed big systems in their boats without a generator, etc. I had a two amp setup on my boat but had a lot of batteries, a house battery and big alternators on my twin diesel engines.

--JK

http://www.seanile31.com

 

[q-ball 10+ year member]

shouldnt there be 2 batts to begin with???

 

[terra 5,000+ posts]

Pyle? No.

 

[q-ball 10+ year member]

Pyle? No.

that too!!!!!

 

[anb.osu]

Yeah... a little concerned about the Pyle, but for 100 bucks and that many features I had to try it.

 

[IDSkoT 5,000+ posts]

shouldnt there be 2 batts to begin with???

Not all boats have 2. They're supposed to. One for the engine and one for accessories. But, there are some lazy mechanics / owners / producers who don't install the second battery.

 

[blackdragonaudi 10+ year member]

that too!!!!!

X3 You should have a dedicated battery to your audio system just in case you do drain that down you have your main battery to start up on.Also they make things that will cut off power to your system when it gets to a point were if it drains anymore it may not start. Here is a link to some that I have used in the past.

http://www.crutchfield.com/g_318550/Battery-Chargers-Savers.html?tp=6795

 

[Relax 10+ year member]

Boats don't need two batterys. Even if you have two, they are in parrallel, and the overall system voltage drops together, but the Ahs available will increase. A very good idea though for boats with multiple large accessories (trolling motor, sound system, depth finders, fish locators, marine radios etc.)

The main problem with boats are their weak charging systems. A large engine like that is very close to what a car or truck has for electronics, however, it has a very small alternator and you should build your system accordingly.

If you have the cash- add a second battery, and see if you can find an alternator to go on that engine. With two batteries- the postives are connected, and negatives are connected. Even though you don't have a "ground" the negative of you battery is where you will connect your amp ground. The only difference is that vehicles have the negative tied directly to their chasis, and a connection made to the chasis is then connected to the negative terminal on the battery.

 

[SeaNile 10+ year member]

Boats don't need two batterys. Even if you have two, they are in parrallel, and the overall system voltage drops together, but the Ahs available will increase. .

Not to get into a pissing contest but not all boats with multiple batteries, or two batteries in this case are together in parallel. Only 4 of my 6 batteries are wired in parallel, all depends on your needs and the cranking amps required to start the engine.

--JK

 

[Relax 10+ year member]

Not to get into a pissing contest but not all boats with multiple batteries, or two batteries in this case are together in parallel. Only 4 of my 6 batteries are wired in parallel, all depends on your needs and the cranking amps required to start the engine.
--JK

You have two batteries just sitting in the boat hooked up to individual electronics I would assume? I wouldn't call them part of the system, since they are not being charged.

Other then that the batteries would have to be in parallel. The postive of your charging system would be connected to all batteries, and the negative too.

The batteries don't necessarily have to be in a line, hooked up with wires running to each battery to the next for them to be parallel. If the positives are the same point electrically, they are parallel.

Also, even if you have two alternators, with a battery on each one, they are parallel. The negatives are the frame and/or housing of the alternator, and by being bolted to the motor have the same potential- call it 0 volts, the postives then have the same potential of +12 volts.

 

[SeaNile 10+ year member]

Not really, all depends if you have an on board battery charger and if so how many bank charger. I have some batteries wired together to get the necessary cranking amps because a huge 8D battery is a pain to work with. On my boat i have the cranking batteries wired together with 2 banks of the charger charging them. I also have a house battery and a battery for the generator. Add in all the on/off/all switches and I have many different options on how to charge them or run them together if I ever needed to. I have the genset alternator, the alternators on each engine and a 3 bank charger.

JK

 

[sexiewasd 10+ year member]

You have two batteries just sitting in the boat hooked up to individual electronics I would assume? I wouldn't call them part of the system, since they are not being charged.
Other then that the batteries would have to be in parallel. The postive of your charging system would be connected to all batteries, and the negative too.

The batteries don't necessarily have to be in a line, hooked up with wires running to each battery to the next for them to be parallel. If the positives are the same point electrically, they are parallel.

Also, even if you have two alternators, with a battery on each one, they are parallel. The negatives are the frame and/or housing of the alternator, and by being bolted to the motor have the same potential- call it 0 volts, the postives then have the same potential of +12 volts.

Sharing a common ground does not make them parallel. You could have a 18volt alternator and a 14volt alternator both charging separate batteries and both using the frame as the ground, if one alternator fails it's battery will not be charged by the other alternator or battery, and it will not be drained by the other system.

 

[IDSkoT 5,000+ posts]

Boats don't need two batterys. Even if you have two, they are in parrallel, and the overall system voltage drops together, but the Ahs available will increase. A very good idea though for boats with multiple large accessories (trolling motor, sound system, depth finders, fish locators, marine radios etc.)
The main problem with boats are their weak charging systems. A large engine like that is very close to what a car or truck has for electronics, however, it has a very small alternator and you should build your system accordingly.

If you have the cash- add a second battery, and see if you can find an alternator to go on that engine. With two batteries- the postives are connected, and negatives are connected. Even though you don't have a "ground" the negative of you battery is where you will connect your amp ground. The only difference is that vehicles have the negative tied directly to their chasis, and a connection made to the chasis is then connected to the negative terminal on the battery.

Not at all. When I used to work as a boat mechanic, often times we'd have one battery working all the accessories, and one battery just for cranking, the only thing they shared was a ground. But the accessory battery could completely die, and the boat would still start. People are careless when they're having fun, so it's a fail-safe. If any boat mechanic wires the batteries together, they're idiots. A few times I even installed a back-up third battery in case the one for just cranking died, he had a back-up so he wouldn't be stuck where ever he was.

But, the alternators on the engines (outboards, mainly) are only like 40-70 amperes. I do agree that the charging system is weak. If you have an inboard motor, then you can easily pop on an after-market type of alternator, or even more. Just my $.02. Talk to your boat mechanic about it.

 

[anb.osu]

Thanks for all the responses....

I am looking at 100 amp altenators for less than 100 bucks new...

Now... the main question is how much play time can I really expect to get with the motor not running, (i know it varies with output/volume and such) but am i crazy to want 1-2 hrs of play time off of one or two deep cycle or dual purpose batteries?

The Isolator system I am looking at charges battery 1 first and then battery 2. I was thinking of maybe moving up to three batteries with 2 of them being "battery two"

 

[pentavolvo 10+ year member]

Ill throw in my 2 cents here i have a 20 ft open bow power boat with a 6 banger I/O. Boat came brand new with a single battery setup and I considered adding a 2nd battery and an isolator right away when doing the stereo system

I run 75x4rms into my speakers and 300rms into a sub. I play the system at prly 3/4 its output with the boat off for close 1.5-2 hours at a pop and the boat fires up every time allthough I am probably pushing my luck. IMO get a nice 2nd battery isolate it from ur starting battery and rock on

 

[c0smo kram3r 10+ year member]

Well we have a Grady White center console with two engines. We have a battery for each and then another one for our radar/gps/loran/bottom machine/radio and what not.

 

[Relax 10+ year member]

I see now how you could wire them without being paralleled, however with only one charging device they would have to be parallel. A bank charger may remedy that.

 

[maddskillzz 10+ year member]

There is no question you are going to need at least 1 more battery..i would go with 2 extra batteries because there is nothing worse than drifting around on the lake with a boat that wont start...I have had a boat all my adult life and have been stuck several times and it ***** ass..get all the battery you can afford.//content.invisioncic.com/y282845/emoticons/titanic.gif.8089b7552c370bcc138aa121756d0c0b.gif

 

[DidUHearThat? 10+ year member]

You should go for the biggest alt and batt bank you can resonable afford and fit. You'll need at least 1 spare (2 would be better) batt on a battery isolator. 1 spare (2 total) will give you about 30 min at about 400 - 600 watts, for 1 hour you'll need at least 2 just for the audio. Skip the pyle gear it's crap and it won't last 1 year. Alpine marine or PDX would be best.

With a 160 amp alt, 1 main battery, a battery isolator and 2 acessory batts you should be able to achive your desired 1 hour run time and still have a fresh batt to start your engine.

Use class D amps because the are much more efficent on power consumption. The subs will eat the most power by far. Using larger drivers will increase efficency withou increasing power consumption. For example a single 15" sub will put out as more bass for less power than two 10" subs. The box size may not be practical but maybe a pair of 12's instead of 10's would be better. More bass for less power. 6 1/2" or 6 x9's for main speakers instead of smaller speakers will also give you more sound for less power.