How to install a 2nd stereo battery

I've seen lots of posts all over the place touching on this lightly, but most seem to know more to start with than I do... so it's a little greek to me.

Does anyone know of a really good instructional (pics would be unbelievable) that gives a step by step on how to go about getting a second battery wired in?

Maybe just post a link to a doc or tell me where to go to find it.

THANKS IN ADVANCE. BIG BIG HELP FOR THIS SEASON.

I have the same question! I can't run my stereo for more than 20 minutes with the engine off. All I have is factory clarion system in my X-2 plus 2 sony xplodes on my tower. What do I do. Can I charge a second battery with my stock alternator. Great question Jeremy, hopefully someone can help us.

From what I hear the best way to do it is to have a A/B switch and a battery isolator. The isolator will let the alternator charge both batteries when the boat is running regardless of the A/B switch position.
You should run all your accessories off of one battery and the other is dedicated to starting. You should also run separate ground wires all the way to the block for both batteries. I'm sure this does not answer all your questions but I hope it helps.

What's up fellas...

I've installed dual batteries in my boat. Here's what I posted as an instructional. Sorry, I don't have any pics.

I went with the Off/1/All/2 Perko switch and West Marine Battery Combiner setup. I wired the starting cable to the COM (common) terminal on the Perko switch and wired the positives from each battery to the 1 post and 2 post on the Perko switch. The 1 post is my starting battery and the 2 post is my accessories/backup battery. I wired the negatives from both batteries together using a negative battery cable, and tied the negative cable from the boat into this as well.

The Battery Combiner is hooked up according to it's instructions. It's simple, just hook each red wire to the positive on each battery and the negative to the negative on one of the batteries and you're all set.

I tested the whole thing out and everything works perfectly. Now I can switch between battery 1 and battery 2, and the battery combiner takes care of charging both batteries when the engine is running, regardless of which battery is being used as the starting battery. While the engine is off....the batteries are isolated. This prevents you from draining your starting battery while you're just hangin out listening to the stereo.

If anyone else is interested in doing this, you'll need:

1 Perko switch (Off/1/All/2) (available at West Marine)
1 West Marine Battery Combiner
1 Battery
1 Battery Box
2 positive battery cables
1 negative battery cable
4 self-tapping screws for mounting the Perko switch
2 self-tapping screws for mounting the Combiner status LED

Be sure not to swith the Perko to OFF while the engine is running, this will toast your alternator.

Hope this helps guys....let me know if you need any more information.



(Message edited by scottie4421 on April 13, 2005)

Running a common ground is not the best way to do it. If you have a problem with the one ground your done.

The way I do it is:

Battey A is your starting battery
Battery B is your Accesory's battery I.E for your light stereo, Drink blender, Plasma TV, Home computer, Tanning bed, ya know the normal stuff people install in boats,

You get a Heavy Duty Solonoid like this.>

http://www.stingerelectronics.com/web/prods/fans.asp

And hook battery A to the main side of the solonoid and Battery B to the AUX side and then run a key'd power leed to the solonoid that will allow both batterys to be connect when the key is turned on and one battey to be removed from the system when the key is turned off, That way if you spend to much time in the tanning bed or watching your Plasma you wont run your starting battery down so you can still get home

Grant's suggestion is what I did with my boat. Stinger 200amp battery isolator separating / connecting two blue top Optima batteries (one deep cycle for stereo, and one regular gell cell starting battery). IMO you can't beat the simplicity and effectiveness of this setup. Since you wanted a pic, here's the wiring diagram I put together for my whole stereo system. The batteries and isolator wiring setup is in the lower right corner of the diagram. Good luck.

Great diagram...this is basically what I did, but used a different brand of isolator.

Walt,

I understand what you're saying, but why don't you tell us how to run another ground....

I think I am going to try it out. Thanks alot guys. How Hard is it to hock this up to the ignition Switch. Do I need to have that done professionally. I think the dealership hates me because I have had the boat three months now and they have had to fix it twice. Wasn't my fault they didn't winterize it good enough before I bought it and the check valves on my ballast broke.

Last Question, I have put some sony xplodes on my tower. Can I use these for the 4 regular boat speakers or are they not water resistant. They would look sweeeeeeeeet with my red boat.

Mike great set up. I may be wrong, but the way you have the isolator set up looks like a Solonoid type. I mean with a isolator, one batt should not run into the other and you have your alt going to batt 1 then to isolator then too batt 2. So I would think that if batt 2 is dead (parting and playing radio for hrs) and you turned on the ign. The voltage would start flowing to batt 2 asap befor the alt had even started to charge or the eng was started.
Let me say this again. This is what I see and may not be how it works so please let me know.

Grant and Mike,

So you don't use the hellroaring isolator I hear so much about? I guess there are several ways to skin a cat. What do you see as the advantage of your setup vs. the hellroaring isolator?

Wow!

The high current relay Grant pictured only costs 13 bucks! Is that right?

This is the Part # of the Part I posted SR200: 200, I think I payed like $40 for it.
I got my'n from Darvex

I dont run the hellroaring isolator, Why. I dont know, I havent fround a Isolater that gives full juice to the battery's, every isolator I tested robb's the power, I havet tested the hellroaring isolator, Mabey i can try it on Judes system

Scott, Just run the two ground Leeds to the bell housing using two different bolts.

Grant, Monks father is a great marine mechanic and he was telling me there is a way to use a isolator without losing voltage. I'll see if I can get more info about it.

Cool That would be great. Ill bring my voltmeter

Unfortunately most of what Monk was telling me was going over my head but the bottom line is you can't do it with all alternators but it sounded like you can with most. Post a pic of the back of your alternator and I'll show it to him and get specifics.

Greg.... Here's the scoop. Yes, the Stinger 200amp isolator I have installed is solenoid controlled, but my batteries are separated and/or connected appropriately. Consider this scenario.

1 - Turn off your boat on the shoreline and crank the radio. When the ignition is off, the isolator is open, so my deep cycle batt is 'isolated' from my starting batt.
2 - Get ready to go and turn the ignition switch to ON, the solenoid closes and connects both batts. My starting batt, which is fully charged, powers the starter and the motor starts.
3 - Once the motor is running, the alternator starts throwing off juice to both batts. Most of the juice goes to my deep cycle since my starting batt is in good shape.
4 - Now back to boarding!

IMO this setup is.....
1 - Inexpensive to acquire and install.
2 - Virtually idiot proof (no manually switching between batts).
3 - Reliable (works every time).

Personally, I went with this setup over the Hellroaring setup mainly due to cost. I know that others have installed the Hellroaring setup, and from what I've read, it appears to be a quality product. I guess the final choice is yours.

There seems to be 2 issues with this setup:

1) When key is on then both batteries are connected. Well if your stereo system and other accesories takes more power than what the alternator can provide then you will drain BOTH batteries and you will be in trouble.

2) If you have the key off and you use the stereo/accesories and drain the accesory battery dead then when you turn the key on it seems you will connect both batteries together and excess current can go from full battery to dead battery (unless the stinger part limits the current going between the two batteries).

Please let me know what you think as I have been investigating adding a second battery and it seems there are disadvantages with every way. It seems it's safer to manually switch between the batteries but it probably worth the hassle.

Here's two good documentation to read: 1) http://continuouswave.com/whaler/reference/dualBattery.html
2) http://rds.yahoo.com/S=2766679/K=battery+combiner+west+marine/v=2/SID=w/TID=F468_72/l=WS1/R=1/IPC=us/SHE=0/H=2/SIG=13t5pe9ge/EXP=1114117349/**http%3A%2F%2Fwww.yandina.com%2Facrobats%2FC70Manual.pdf%23searc h%3D%27battery%20combiner%20west%20marine%27