# Need help adding a 2nd battery for a boat installation



## BlackLac (Aug 8, 2005)

I have never done anything with adding 2nd batteries, so I am a complete newb in this area.

My friends dad want an updated system in his boat. It's a 96-97? Searay. It just has an old marine HU and 4 coaxials (5 1/2's?). One side is blown. He wants a new HU with iPod capabilities and new speakers. I meantioned a 2nd battery would be a good idea, cause I planned on using an amp or two. He thought that was a great idea. I would like to have the amp and HU on the 2nd battery, both batteries charged off the alternator, obviously. I've never installed an HU in a boat, is it much different than a car? Is it east to rewire the power wire to a different battery? I just got the budget today, it was alot less than what I was hoping. He said $5-800. With a new HU, 2 sets of replacement speakers, 4 channel amp I'm already at about $650. Is there room in this budget for a 2nd battery? What components do I need and how do I install them? I was initially planning on a sub and sub amp, but budget cut that out.

He really liked the idea of a 2nd battery just for the system, so I think he will make that work no matter what the budget is.

Any help would be appreciated.

My equipment I plan on using so far:

HU: Clarion DXZ785USB (for iPod use) ~$230 shipped
Component Amp: Alpine MRP F550 ~$200 shipped
(Found matching Eclipse amps on Ebay too, XA1000 and XA4000. There efficiency should be great for this setup. About $340 shipped for the pair! If budget alows a sub, otherwise just the 4 channel for $190 shipped)
Speakers: 2 pair Elemental Design 6000v.2's They can be mounted with tweeter on woofer as coaxials. ~$200 shipped (I'm open to suggestions, I don't think I could fit seperate tweets and woofers, maybe I could with ~5" mids. Considering no sub, the easily mounting 6.5" from eD looks like a good fit.)


(oh yeah, I will get specifics but it's a GM inboard motor.)


----------



## verbier123 (Jun 29, 2008)

I just did an install in a 97 sport nautique I bought this spring.

Head Unit Clarion MARINE M475 140 on ebay
minus
2volts out, but has 
Plus
3 outputs
water resistant


----------



## verbier123 (Jun 29, 2008)

Speakers
Polk MMC650 $90 pair

Highly regarded as the best marine speakers out there bar none

There decent speakers and play fairly loud, price is right. With wind and engine noise, these are about the best I would buy. Plus marine rated


----------



## verbier123 (Jun 29, 2008)

Perko battery selector switch ~50 West Marine

This is what you need to do a 2 battery system and is what I used

Wire all in 0 gauge.
Knuconcepst wiring ebay roughly $50 depending on how far you go.


----------



## Oliver (Jun 25, 2007)

I could tell you about my father-in-laws, but there really would be no point !

He had a Starcraft with an inboard v8.

He used a rotary knob, the settings were 0 , 1[battery] or 2 [ 2nd battery ] or 1&2 [ both batteries ].

he was a master electrician [ he is deceased now ].

If the boat was running both batteries were being charged by the alternator.

When we were fishing, either battery could be used for tv or radio.


----------



## verbier123 (Jun 29, 2008)

Your at about 450 now, new battery puts you at $525.

Budget crunch.

Find some cheap amps, I used some older amps I had laying around. You are going to be disapointed without a seperate amp for the polks...

hopefully you can find something for 100 bucks a piece if you dont already have some laying around. Otherwise i would go with clarion marine rated amps as they are marine rated at around 200 a pop.

Sub
polk momo 12

I got one off ebay for 60 bucks, hard to find lately. used to be on frys too. otherwise try a db series.

best of luck


----------



## jp88 (Jun 25, 2007)

If you want to charge 2 batteries with one alternator you need one of these. 
http://www.opentip.com/Sporting-Goods/Promariner-Battery-Isolator-Bat-p-662465.html

A battery switch is only going to charge the battery/batteries that are selected. This will allow both batteries to be charged but will not allow one battery to kill the other.

The size wiring that you need to use depends on the alternator current capacity and the distance to the batteries. 

make sure to use proper circuit protection and I would also recommend using tinned boat wire.

If you have any specific questions or would like more detail feel free to PM me. I am a Marine electrician/electronics tech by trade.


Shamesless plug I have a used battery isolator in my garage I would be happy to sell you for cheap. I can also help you out with the sourcing of tinned boat wire (tip DO NOT buy boat wire at West Marine or Boaters World they are VERY over priced on wire and connectors.)


----------



## verbier123 (Jun 29, 2008)

jp88 said:


> If you want to charge 2 batteries with one alternator you need one of these.
> http://www.opentip.com/Sporting-Goods/Promariner-Battery-Isolator-Bat-p-662465.html
> 
> A battery switch is only going to charge the battery/batteries that are selected. This will allow both batteries to be charged but will not allow one battery to kill the other.
> ...



Battery isolators are not fool proof and it is still possible to leave yourself stranded. Sometimes they don't disconnect before the battery is too weak to turn the starter. If you want to charge both batteries off the alternator with the perko switch, all you do is move the dial to "1+2". I think you will most often deplete your batteries when you have the boat parked and the radio on. Your also better off recharging your batteries with a "smart" trickle charger after the boats back in the garage or lift. To do that, you turn the dial to off and charge each battery seperate. Turning the dial to "off" is also the only way to insure that you don't kill your battery by accidentally leaving the radio on. just my 2 cents


----------



## jp88 (Jun 25, 2007)

verbier123 said:


> Battery isolators are not fool proof and it is still possible to leave yourself stranded. Sometimes they don't disconnect before the battery is too weak to turn the starter. If you want to charge both batteries off the alternator with the perko switch, all you do is move the dial to "1+2". I think you will most often deplete your batteries when you have the boat parked and the radio on. Your also better off recharging your batteries with a "smart" trickle charger after the boats back in the garage or lift. To do that, you turn the dial to off and charge each battery seperate. Turning the dial to "off" is also the only way to insure that you don't kill your battery by accidentally leaving the radio on. just my 2 cents


Most battery isolators are diode based. There is no Disconect per say. If It allows one battery to kill the other it has a shorted diode and is broken.


----------



## verbier123 (Jun 29, 2008)

jp88 said:


> Most battery isolators are diode based. There is no Disconect per say. If It allows one battery to kill the other it has a shorted diode and is broken.


I should have looked more closely at what you were recomending. I personally would never use a diode based isolator due to the ~.5 volt loss. You will never get your battery fully charged. I assumed you were refering to an isolator/combiner. As in this:
http://www.hellroaring.com/bic75150.php

Those work ok, but quite a bit more expensive than a perko type switch. And not as reliable.


----------



## jp88 (Jun 25, 2007)

verbier123 said:


> I should have looked more closely at what you were recomending. I personally would never use a diode based isolator due to the ~.5 volt loss. You will never get your battery fully charged. I assumed you were refering to an isolator/combiner. As in this:
> http://www.hellroaring.com/bic75150.php
> 
> Those work ok, but quite a bit more expensive than a perko type switch. And not as reliable.


A perko switch is the most unreliable method of battery isolation as it counts on the boat operator to remember to put it in the correct position. It usually seems as if most boat owners end up leaving them in the ALL position most of the time.


----------



## BlackLac (Aug 8, 2005)

There's really no point in using Marine speakers is there?

I will definetly amp the speakers. I'm at $605 without a sub and $803 with a sub and amp to power. Still need wiring, accessories and 2nd battery stuff...

I'm pretty set on those Eclipse amps. $184 shipped for the XA4000, 125x4 and very efficient (ice power). If budget allows the sub, $50 for an eD 13kv.2 D4 and Eclipse XA1000 for $148 shipped. Those 3 pieces are locked in at those prices. The comp speakers, I can change those, but I don't want to sacrifice quality.


My biggest issue is getting a 2nd battery running. What are my options and how does each option work? Why can't I just wire up a 2nd battery and have both connected to the alt.? Too much for the alt. to charge both at the same time?


----------



## jp88 (Jun 25, 2007)

BlackLac said:


> There's really no point in using Marine speakers is there?
> 
> I will definetly amp the speakers. I'm at $605 without a sub and $803 with a sub and amp to power. Still need wiring, accessories and 2nd battery stuff...
> 
> ...


You can just wire both to the alternator. The down side to this is while it will allow you to run the stereo for longer without the engine running it offers you no protection from killing your start battery.


----------



## verbier123 (Jun 29, 2008)

BlackLac said:


> There's really no point in using Marine speakers is there?


Thats what I thought until I hit a few waves and had water splash inside the boat. Chances are water is going to come in contact with the speakers at some time. If you don't mind replacing speakers every now and then go for it. I know Polk isn't known in the car audio would as exeptional, but you can get the stuff for cheap on ebay and it is very good for the price. Take your friends boat out this weekend (take a radioshack SPL meter with you.) Being ouside is a fairly noisy environment if you consider engine noise, talking passengers and wind noise. I don't think considering your budget, that you should buy anything other than the polks, there built to wistand the elements. If you don't trust me, go to www.planetnautique.com and check the forum. Their going to tell you polk for the interior and nvs or wetsounds for the tower. No one makes a comparible speaker right now. Trust me I am not a big polk fan but these are the best out there right now. You could also check with any of the big wakeboard boat dealers, on almost every single $60k+ boat they use polk.


----------



## verbier123 (Jun 29, 2008)

jp88 said:


> A perko switch is the most unreliable method of battery isolation as it counts on the boat operator to remember to put it in the correct position. It usually seems as if most boat owners end up leaving them in the ALL position most of the time.


The key is to NEVER put it in the "1+2" condition, when you hit they lake with both batteries charged you start the boat and then leave it on 1 for a few minutes to recharge the battery from starting, then you either leave it on 1 or switch to 2. When you turn the motor off and turn up the stereo, turn it to 2. If you forget and kill the battery, the other battery (depending on what you did) will still be good. Just don't turn it to all, and charge your batteries off a charger when you get home. Seems pretty simple to me, I run a 1200 watt rms system off my boat and have't had any problems.

http://www.westmarine.com/webapp/wc...=true&storeNum=5002&subdeptNum=9&classNum=297


----------



## verbier123 (Jun 29, 2008)

BlackLac said:


> Why can't I just wire up a 2nd battery and have both connected to the alt.? Too much for the alt. to charge both at the same time?


If you do, you should use identical batteries. Different batteries charge at different rates and is is generally known not to hook two differnt types of batteries together. Also (1) There is no way to charge one battery and not the other and (2) deep cycle batteries - high amp hour (the kind you should use for running the stereo for long times) do not have the cranking amps that a regular battery has and vise versa.


----------



## sqImpalaLS (Apr 28, 2008)

No boater would recommend two identical batteries. I am going to do an install in my boat next year (spent all the money buying the boat) I will use the battery Perko isolator (make sure you explain how he should use it as directed above). For batteries 1 starter and one deep cycle.

Also, definately use marine grade eqipment, it's an entirely different environment. There are some high quality US made marine speakers from DC Gold DC Gold

I haven't decided on speakers but probably will go with DC Golds.

For an amp I have a Tidal Audio TP 1100.6, it was a prototype I got from Steve Mantz. You can call Tidal and see if they have anymore (they charge $150 for protos if I remember correctly) It's a 6 channel Marine grade amp. Tidal Audio Contact

Good luck and be sure to post some pictures.


----------



## BlackLac (Aug 8, 2005)

It won't be pic worthy. 

When I was talking about just running both batteries off the alt, as is, I was going to leave the existing battery as is and add a 2nd for just stereo only. How would they both die?

If someone wants to explain how to setup those perko switches, I would greatly appreciate it. 

I guess I can understand why marine speakers would be a good idea, waterproof and all. What about amps? There is really no way the amp I plan on using will get wet, short of the boat sinking.  Any real reason to get a marine amp in this situation? I'm really liking that Eclipse XA4000 because its low current draw and it's way more power than I need, which means even less draw.


----------



## BlackLac (Aug 8, 2005)

Verbier123 - What line of Polk's? The MOMO's are in my price range. I know the Comp set sounds good for the cheap price. If you meant the SR's, way out of my price range. 

I don't know, I'm still undecided about marine or car speakers. The fronts wont get wet. The rears _could_, but... I just don't know. 

Is there a type of cone that would be ok, even if it's not Marine/waterproof? Some car woofers sure look/feel waterproof.


----------



## jp88 (Jun 25, 2007)

BlackLac said:


> It won't be pic worthy.
> 
> When I was talking about just running both batteries off the alt, as is, I was going to leave the existing battery as is and add a 2nd for just stereo only. How would they both die?
> 
> ...


1. If you wire both batteries directly to the alternator then they are in parallel . The wires from both that go to the alternator are connected together hence they will both be running your stereo, and your starter.

2. If you use a perko switch to isolate the batteries You will still be using either on battery or the other for both starting and running your stereo. Or both if you have the switch in the all position.

3. Most car speakers are moisture resistant, but not splash resistant. If the speakers are in a place they won't get splashed I wouldn't worry about using marine speakers.

4. I would also not be concerned with marine amps, I would just make sure to mount the amps in a dry location.

I will make you a diagram of how to wire the batteries in both configurations. I will try to get them on here tonight.


----------



## verbier123 (Jun 29, 2008)

BlackLac said:


> Verbier123 - What line of Polk's? The MOMO's are in my price range. I know the Comp set sounds good for the cheap price. If you meant the SR's, way out of my price range.



Yes, the polk momo series. If possible, I would try to modify the boat to fit the larger 6.5" speakers, otherwise they to make them in 5.25. Just seach on ebay for polk momo and you will find them. Besides the cones, the baskets of speakers can also rust/corrode. Just stick with the momos, good bang for the buck. Marine amps use components that don't rust, if you have to buy new, I would get the clarion marine amps just because they are marine rated and fairly cheap. The eclipse amps are a good idea being class d. I would have recomemded the superior alpine marine pdx series (also class d), but they were a little too much for your budget. If you want the eclipse amps, try to put them under a seat or someplace they are fully covered.

The perko switch comes with directions, you just have to make sure you use 0 gauge wire. I recomended west marine beacuse they have a lot of stores and it is usually in stock. They should be able to help you out explaining how it works too. Try knukoncepts on ebay for wire, their wire is tinned too which is a bonus for marine.


----------



## jp88 (Jun 25, 2007)

verbier123 said:


> Yes, the polk momo series. If possible, I would try to modify the boat to fit the larger 6.5" speakers, otherwise they to make them in 5.25. Just seach on ebay for polk momo and you will find them. Besides the cones, the baskets of speakers can also rust/corrode. Just stick with the momos, good bang for the buck. Marine amps use components that don't rust, if you have to buy new, I would get the clarion marine amps just because they are marine rated and fairly cheap. The eclipse amps are a good idea being class d. I would have recomemded the superior alpine marine pdx series (also class d), but they were a little too much for your budget. If you want the eclipse amps, try to put them under a seat or someplace they are fully covered.
> 
> The perko switch comes with directions, you just have to make sure you use 0 gauge wire. I recomended west marine beacuse they have a lot of stores and it is usually in stock. They should be able to help you out explaining how it works too. Try knukoncepts on ebay for wire, their wire is tinned too which is a bonus for marine.


Unless you are in a hurry to get something I would steer clear of West Marine, Or Boaters World. I know for a fact I can sell most marine electrical stuff for half what they do and still make a profit. If you are interested in saving some money on Perko switches, heat shrink, connectors, PM me.


----------



## jp88 (Jun 25, 2007)

here is a site I found that may be very helpfull to you. It has some basic diagrams and explanations of Battery wiring on a boat.
http://www.cmsquick.com/tech_03_batsys.html


----------



## BlackLac (Aug 8, 2005)

Wow, thank you SO much guys. I really sppreciate it. If there's anything esle feel free to add.

Thanks!


----------

