Battery "system" advice for new sound system

Hey guys, I've been reading through some of the new and old "battery" threads and trying to get a handle on what I should be doing. Find myself getting more confused then when I started.

To recap, I'm installing a completely new WS system in my 2003 MC X2, to include 3 new amps which I approximate will total about 2500watts. Currently, I only have the one stock battery.

If you could please advise what I should do to upgrade this battery "system," that would be fabulous. I don't want to say that money is not an object, but I do have the cash to spend to make it right. I spend Sundays partying at the sandbar. Apparently, I need at least 1 or 2 batteries dedicated to the stereo, some sorta switch, and now I'm learning a charger (which I assume is for when I'm on the trailer).

Brian,

I am a big fan of the KISS - Keep it Simple Stupid motto when it comes to anything electrical on a boat.

Here is what I run.

First off, I dont rely on my alternator to ever charge my stereo bank of batteries. When the day comes that I can't play my stereo from draining my batteries, I will do two things. Turn the stereo off for the day and then add another battery to the system immediatly.

Also, my batteries stay on a charger 365 days of the year. They only come off when I am on the water.

My setup is as follows:

100 amp alternator
4 Optima Blue Tops (3 for stereo)
Blue Sea 5511e Dual Circuit Switch
Dual Pro Charger 2 bank 12 volts total

Possibly switiching to Deka Sea Mates this spring.

That's a lot of batteries. If you don't charge the stereo batteries with the alternator, why the need for the 100 amp alternator?

And just due to my ignorance, what's the issue with charging the batteries with the alternator?

My alternator went bad a couple years ago, so I had the option to upgrade and I did. Alternator still charges the starting battery.

3 is not really that many batteries for the stereo if you want to play hard for hours.

Trying to charge 4 batteries with one alternator puts a ton of strain on the alternator and can potentially destroy it.

That makes sense.
Now I'm curious how many batteries I'm gonna need.

Brian, unless you have a huge heavy duty alternator that you can actually use as a battery charger your alternator is used as a battery maintainer. With the systems people have there is no way for the alternator to keep up with the draw these amps have. The alternator is working as hard as it can all the time then and it still won't ever keep the batteries maintained like they should. This is why you should get an onboard charger.

Brain, the more the better. Make sure they are a deep cycle battery for the stereo bank.

I think a good place to start would be two of the Deka Sea Mate 31 series. They have 105 amp hours each and would give you the equivalent of 3.8 Optima Blue Tops (24 series).

You should be able to get them for $200 each

Dollars to amp hours, golf cart batts get the nod all day long.

For $400, you could have 4 interstate 6v batts at 225 amp/hrs each. Wire two in series to give you a a 12V 225 amp/hr rating. Link the two 12v banks in parallel and you've got 450 amp/hrs.

I wished they had a Deka dealer her in Raleigh NC!!

OK, I found a place here in Raleigh and the Group 31 is $210.00 each. Not bad and cheaper than the Optima's

(Message edited by ColombianSurfer on February 19, 2010)

Are folks really putting golf cart batteries in their boats?

Where do you guys put all these batteries? I guess either in the back storage compartment or in the passenger storage?

How does amp/hr rating translate to battery life? I suppose it depends on my system, but with my system how long can I expect for example the two deka 31's to last? Depends on volume right?

Golf cart batteries are great for deep cycle use. The downfall is they are tall, you have to do them in sets of 2 and most are not AGM/sealed style batteries. They need to have the water levels checked every once in a while. Deka does actually make an AGM 6v golf cart battery but it has less of an AH rating than the standard GC battery.

The GC15 is a standard 6v Golf cart battery and has a 20/AH rating of 215.
The 8AGC2 or 8AGC2M only have a 20/AH rating of 190.

When in series you don't double the ratings like you would with 2 batteries in parallel. The 8A31DTM group 31 AGM battery has a 20/AH rating of 105 so about 210 when 2 are in parallel. I would almost expect the golf cart setup to have a longer life in the same deep cycle application because they have thicker/larger plates, but I don't think by much.

David, can you make it to High Point, NC?

http://www.eastpenn-deka.com/ZipSearch.aspx?pageid=843

East Penn Manufacturing Co., Inc.
2001 Nuggett Road
High Point, NC 27263
Phone: 336-861-5672

(Message edited by polarbill on February 19, 2010)

If you understand how to manage your system, its limitations and risks, then a simple manual switch can be just as effective as more complex options. You're only giving up convenience if you're confident you're not going to overlook something that could be harmful.

If you have multiple large AGMs run down to 11 volts and initially drawing 25 amps apiece, plus 50 or 60 amps of draw from the stereo plus 15 amps to run boat operations, your alternator may be turning rainbow colors like an exhaust header. This is why you have to come to grips with the real demands of really big audio systems. You can't just pile on more batteries and leave it at that.

When it comes to your charging system it does seem complicated. But the benefits of doing it right the first time far outweigh the savings of taking shortcuts.

David
Earmark Marine

David, what you say makes sense, but I'm not sure what to do here still.
What charging system do you recommend? I'm fully ready and believe in doing this right, just not sure how.

Yes, people really do put golf cart batts in their boats. I built a battery box to two blue tops and two GC batts.

I've got 2 Stinger SP1500D's for my stereo, and 1 SP800 for starting the boat and powering accessories. 3 6A/hr charger's are hard-wired to charge the batteries overnight. My stereo consists of 2 Syn1's, 1 Syn6, and 1 Syn4. I've gone for 2 weeks at a time without recharging and mostly stay in coves or at the beach playing the stereo.

X2 on the alternator not charging. It makes me laugh to see people at the end of the day start their boat and rev it up thinking it's gonna charge the batteries.

4 6volts will get you the longest play for the least money. To get the same out of 12v batteries you will spend more than double the money. Check out US 2200 batteries for $79 each.

What about a battery called Odyssey, supposed to be used by the military or something?

Why do you need an onboard charging system? I have a regular 2A charger, is it good enough?

Originally Posted by jonyb

I've got 2 Stinger SP1500D's for my stereo, and 1 SP800 for starting the boat and powering accessories. 3 6A/hr charger's are hard-wired to charge the batteries overnight. My stereo consists of 2 Syn1's, 1 Syn6, and 1 Syn4. I've gone for 2 weeks at a time without recharging and mostly stay in coves or at the beach playing the stereo.

X2 on the alternator not charging. It makes me laugh to see people at the end of the day start their boat and rev it up thinking it's gonna charge the batteries.

Do you have any pictures of the install on your personal boat?

Ok, I have my system installed now. I have syn1, 2 syn2's, and a syn4. I have 3 Deka31's for the stereo, and another fourth battery just for start, a switch, a VCR "thing", and onboard charger. My boat guy told me to charge the batteries overnight on switch setting "0." I went out yesterday and the stereo only lasted less then an hour at pretty high volume.

And would not play at all on the ride home with switch at "1 and 2." Weird?

I think I should get more time, what am I doing wrong?

Check out the AGM batteries made by www.xspowerbatteries.com

I bought two 3100 series batteries to run my system this season - which will consist of 2 syn4's and a syn1.

Now to buy an onboard charger...

225 AH a piece so 450 total. Never been unhappy with mine.

Am I right to think then that you guys with big battery banks lie the 450ah's worth of cart batteries rely entirely on onboard chargers and don't connect the batterys to the alternator?

I ask because I am installing a system that will draw 85amps but I only have a 65amp alt and single battery and don't want to fry the alternator!!

Matt, how much stereo are you running off those batteries and how much playing time are you getting with engine off?

Showmethebutter, my understanding and continuing education in these matters indicates that, yes, you should not rely on your alternator as it, even if upgraded, is ill equipped to keep up with actually charging batteries depleted from a serious stereo system.

Matt, using 6v batteries you have the equivalent power as a 12v with 225 aH, still probably plenty. I like golf cart batteries, they charge and maintain about 0.4v higher than AGMs, this translates into about 20% more playing time.

AH ratings are next to worthless when you are talking about audio applications, unless you are running a very small system (10-20 amp pull). AH testing is done at very low amperage draws for extended periods of time. You need to look at the instantaneous power output and the design of the battery. Thinner lead plates allow for more discharge faster and faster recharge times. Also the more plates you can pack into the battery the higher power output you will have, and extend the life of the battery with multiple discharge/recharge cycles.

Showmebutter/brian b: correct, you isolate this bank from your boat's starting/charging system. Rely on your onboard charger to recharge at the dock/house.

FYI, I had great success this weekend with the following strategy (you can see what batteries and stereo I'm running above):
Get to party cove and switch switch to "2", turn off boat
run in boat speakers only (syn1 and syn2) with sub gain down fairly low OR run tower speakers cranking, either/or for 30 minutes
run idle boat for 15 minutes
Repeat
The 2sum tower set up powered with 2 syn2's played loud all day like this.

I think it's mostly playing your system smarter not harder.

Originally Posted by brian_b

FYI, I had great success this weekend with the following strategy (you can see what batteries and stereo I'm running above):
Get to party cove and switch switch to "2", turn off boat
run in boat speakers only (syn1 and syn2) with sub gain down fairly low OR run tower speakers cranking, either/or for 30 minutes
run idle boat for 15 minutes
Repeat
The 2sum tower set up powered with 2 syn2's played loud all day like this.

I think it's mostly playing your system smarter not harder.

Brian, did you dealer ever get my email? Did you end up wiring the switch with the VSR the way I suggested?

If you did having the switch in position 2 means that you are draining down you starting battery and the stereo batteries. This may give you slightly more play time but you have the chance of running your start battery too low and not having enough juice to start. This will also will lead to shortened life of all electronics in the boat as well as the starter and alternator.

Hmmm...I don't know if he did actually change the wiring around. I am bringing the boat in tomorrow for some unrelated stuff, so I was going to discuss that tomorrow. Thanks for the heads up on that issue though.

He definetely got your email though, so did I. VERY helpful, as usual.

Presumptively my dealer knows where I should have my switch under your wiring scheme. I will review with him. He did not tell me to use "2', I just used that assuming the wiring was "original."

I will let you know...

batteries confuse me............ :S .... golf cart batteries are better..... no deep cycles are.... no way AGM is the best....... I have no clue what to do also

What is everyones opinion on the 4D batteries??

I agree with you Brian on using the stereo smarter instead of harder because I have to do this all the time in order to save battery power for the next day if the boat doesnt come off the water. How do most of you guys keep a seperate bank of batteries charged while the boat stays on the water for the weekend while your camping?

bump? Anybody on charging while camping?

I know alot of people are against Optimas, but here is my new triple Optima D31M setup (the Tray/Box was made here
http://www.optimatrays.com/index.php?body=custom_trays:

Pete (petrey10)
batteries confuse me............ :S .... golf cart batteries are better..... no deep cycles are.... no way AGM is the best....... I have no clue what to do also

I need batteries for my boat, and the more i read on this forum the more i get confused.

I guess i should be looking for golf kart batteries. Seems they have the highest AH rating for playing without the support of the alternator.

yeah man... someone says GC batteries another will say Wet Deep Cycle marine batteries.... other say spread 1500 bucks and get the best batteries.... I got no freaking clue!!!!!!!!!

I got 2 us2200 golf cart batteries. 232 amp-hours for 220$ to my door. I guess i can'T go wrong with that...

Originally Posted by xaggie

225 AH a piece so 450 total. Never been unhappy with mine.

Don't you mean 900ah total if it's 4x225? Or am I missing something?

he's got 2 in pararell 2 in series. i beleive with the ones in series you don't add up the ah. but you double up the voltage.