SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: flytime on January 05, 2008, 09:00:27 AM

Title: Second Battery
Post by: flytime on January 05, 2008, 09:00:27 AM
I am going to add a second battery to the boat strickly to power the stereo. Its not a huge system. Head unit, amp, couple of 6x9's. Just dont want to take the chance of a dead battery. Any opinions on switches or anything else? Thanks in advance.

Bob
Title: Re: Second Battery
Post by: Jetaholic on January 05, 2008, 09:08:39 AM
You can use a 3-way battery switch...most marine shops carry them. Or you can just hook the second battery up in parallel to the main battery (i.e. positive - positive, negative - negative). Hooking them in parallel will double the current capacity of the electrical system plus the alternator can charge both batteries.
Title: Re: Second Battery
Post by: flytime on January 05, 2008, 12:16:42 PM
If I hook them up parralel will the radio draw from both batteries or just the one? If I decide to put in a switch, I can still have the alternator charge both correct?
Title: Re: Second Battery
Post by: Jetaholic on January 05, 2008, 12:42:42 PM
If I hook them up parralel will the radio draw from both batteries or just the one? If I decide to put in a switch, I can still have the alternator charge both correct?

By connecting two batteries in parallel, electrically the two batteries become 1 battery with double the current capacity.

The switch I believe has 3 positions: Bat 1, Bat 2, and Bat 1 & 2. The alternator will only charge the battery that is switched on by the switch.
Title: Re: Second Battery
Post by: hotrod56cars on January 05, 2008, 12:47:29 PM
Years ago I had a Dodge Ramcharger that I added a bunch of electrical crap to. I ran two batteries connected in parallel. What I eventually ended up with was 2 batteries half charged. I added a battery switch (just like the one Jetaholic is referring to) and the problem went away. I would never add a second battery without a switch, automatic switch or manual are available. I used a manual and it was awesome having it. I could use the stereo or winch and not worry about the thing not starting when I was done doing whatever I was doing.
Title: Re: Second Battery
Post by: rebel on January 05, 2008, 01:02:33 PM
A battery switch is good if you want to isolate the batteries, select which ones are being used (charged or drained)
but if you set up solenoids, you can charge both batteries, but only drain/use the batteries that the equipment is hooked up too.
Think of it this way...  wouldn't it be nicer to always charge both batteries, but only use one for the starting/running of the motor
and the other battery for sterio or fridge (aka beer cooler) ?

check out this web page...  answer all your questions!
http://www.bcae1.com/battiso.htm (http://www.bcae1.com/battiso.htm)

-Rebel
Title: Re: Second Battery
Post by: Jetaholic on January 05, 2008, 01:16:30 PM
Yeah what these guys said. For running the stereo while you're beached, it's definitely better to have 2 seperate batteries....one for starting and one for accessories.  Once the boat is running it's a good idea to switch the battery switch to both so that they can both charge.

There is no way to charge both batteries off of 1 alternator and keep them isolated from each other at the same.
Title: Re: Second Battery
Post by: rebel on January 05, 2008, 01:20:23 PM
Yeah what these guys said. For running the stereo while you're beached, it's definitely better to have 2 seperate batteries....one for starting and one for accessories. There is no way to charge both batteries off of 1 alternator and keep them isolated from each other at the same.

Agreed, unless your worried about weight...  then why have a sterio in the first place  ;D

-Rebel

also forgot to add...  check out this article from Forkedup...  very good info on subject as well

http://www.socaljetboats.com/index.php/topic,2323.0.html (http://www.socaljetboats.com/index.php/topic,2323.0.html)  ;)
Title: Re: Second Battery
Post by: beerjet on January 05, 2008, 02:49:37 PM
There is no way to charge both batteries off of 1 alternator and keep them isolated from each other at the same.
I was talking to a stereo shop close by and dude said this is exactly how he wires up boats . So one battery only runs the boat while the other only runs the stereo .  ???

-beerjet-
Title: Re: Second Battery
Post by: Marcsrollin on January 05, 2008, 03:07:55 PM
I have a switch. It has 4 positions on it batt 1,batt 2,all and off. Off works great to disconnect both batteries during long storage.
Title: Re: Second Battery
Post by: flytime on January 05, 2008, 03:39:02 PM
Marc,

Where did you find that switch?

Bob
Title: Re: Second Battery
Post by: Marcsrollin on January 05, 2008, 03:51:30 PM
It's just the standard one you find a t any marine shop or west marine for around $25.


[attachimg=#]

Title: Re: Second Battery
Post by: propless on January 05, 2008, 09:05:08 PM
There is no way to charge both batteries off of 1 alternator and keep them isolated from each other at the same.

 Yes there is , its called a multi-battery isolator  ::).  Thay have been used in boats and motorhomes for years for just this reason. 
 Heres an example. http://www.emarineinc.com/products/alternators/isolators.html

 You can also use a duel output alt , like two alternators in one case.
http://www.boatelectric.com/91ddimensioncurves.htm

 But in most cases the switch like marcsrollin showed will work fine and be verry trouble free.  ;D ;D
Title: Re: Second Battery
Post by: wanabe on January 05, 2008, 09:32:22 PM
Yes there is , its called a multi-battery isolator  ::).  Thay have been used in boats and motorhomes for years for just this reason. 
 Heres an example. http://www.emarineinc.com/products/alternators/isolators.html

 You can also use a duel output alt , like two alternators in one case.
http://www.boatelectric.com/91ddimensioncurves.htm

 But in most cases the switch like marcsrollin showed will work fine and be verry trouble free.  ;D ;D
seems to me this multi battery isolator would be the way to go; no need to worry about flipping a switch; and easy hook up (http://www.emarineinc.com/products/alternators/iso1alt2bat.html).

Title: Re: Second Battery
Post by: GAWnCA on January 05, 2008, 10:17:29 PM
seems to me this multi battery isolator would be the way to go; no need to worry about flipping a switch; and easy hook up.

Although I haven't considered a second battery yet, it seems like a great way to do it.  It works in motor homes, it'll surely work in a boat.
Title: Re: Second Battery
Post by: rebel on January 05, 2008, 11:45:11 PM
Did no one check out my first link?  I mean really I go through all the trouble to show you all the options on one web page...
and no...  you all skip over, read to the end and post your own little web site pagey thingy's  ::)

 ;D ;D ;D  >:D  :-*

-Rebel
Title: Re: Second Battery
Post by: jet boat performance on January 06, 2008, 09:38:22 AM
IMO the "guest Battery switch is the "hot set up" we always encourage dual batts , my flatty even has a back up fuel pump Last thing you want is to be "kickin it some where" get ready to go and .... dead battery cant say the isolater wouldn't work but just more to go wrong.We  actually have a  multi position switch that comes with a  one,two,both,off/key lock for security Tom
Title: Re: Second Battery
Post by: wanabe on January 06, 2008, 10:05:21 AM
Did no one check out my first link?  I mean really I go through all the trouble to show you all the options on one web page...
and no...  you all skip over, read to the end and post your own little web site pagey thingy's  ::)

 ;D ;D ;D  >:D  :-*

-Rebel
LOL

I did click your link; good stuff but because of the length, I started scanning instead of reading; the other link(s) was just an easier read for this simple mind  :o
Title: Re: Second Battery
Post by: hotrod56cars on January 06, 2008, 12:10:27 PM
... dead battery cant say the isolater wouldn't work but just more to go wrong...

 ::)   ;)
Title: Re: Second Battery
Post by: propless on January 06, 2008, 12:36:42 PM
Did no one check out my first link?  I mean really I go through all the trouble to show you all the options on one web page...
and no...  you all skip over, read to the end and post your own little web site pagey thingy's  ::)

 ;D ;D ;D  >:D  :-*

-Rebel

 Sorry, Mr Rebel sr !!!
   I was bad, I did not look at it  :-[. (propless hangs head in shame) You are the master of all things, and I should never have over looked your link !  It will never happen again [attachimg=1].
Title: Re: Second Battery
Post by: Legal Chemistry on January 06, 2008, 03:02:44 PM
Undoubtedly get a Perko switch:  One battery for starting, one battery straight to stereo. 

This way you can isolate running the tunes on the beach and still have a battery to get you home.  When you motor switch it to "all" to charge it back up.  The only problem is you'll drop amps if you your beach time is too long putting strain on the amplifiers (lots of heat!.)

Title: Re: Second Battery
Post by: rebel on January 06, 2008, 03:29:31 PM

 Sorry, Mr Rebel sr !!!
   I was bad, I did not look at it  :-[. (propless hangs head in shame) You are the master of all things, and I should never have over looked your link !  It will never happen again (Attachment Link) .

LMAO...   :D  almost PMSL   it had pitures and interative stuff and everything  8)
you are forgiven young one ;)

-Rob
Title: Re: Second Battery
Post by: jet boat performance on January 06, 2008, 03:58:45 PM

 Sorry, Mr Rebel sr !!!
   I was bad, I did not look at it  :-[. (propless hangs head in shame) You are the master of all things, and I should never have over looked your link !  It will never happen again (Attachment Link) .

Jeff you should prolly go spank yourself !!
Rob great post I just missed it    T
Title: Re: Second Battery
Post by: flytime on February 17, 2008, 06:12:41 PM
Second battery update. My buddy in Bako got it installed over this past weekend and he says he is really happy with the way it turned out which is good news to me because he is more anal retentive than I am. No more worries about a dead battery after blastin the radio all day at the sand bar. Here is the finished product. Thanks for all the ideas everybody and thanks to JBP for dialing me in with the correct switch.

[attachimg=1]

[attachimg=2]

[attachimg=3]

[attachimg=4]
Title: Re: Second Battery
Post by: propless on February 17, 2008, 07:31:36 PM
Ummm, your not finished, right?
Title: Re: Second Battery
Post by: flytime on February 17, 2008, 07:34:35 PM
Just need to hook up the cables if thats what you are refering to. ::)
Title: Re: Second Battery
Post by: propless on February 17, 2008, 07:51:39 PM
Just need to hook up the cables if thats what you are refering to. ::)

 Yea, LOL . The ground cable looked a little small on the batt that had one  ;D.
Title: Re: Second Battery
Post by: speedymopars on February 17, 2008, 08:00:01 PM
Just as a point of information - a battery isolator is just two high current diodes with the alt charge wire in the middle. No contacts to wear out or corrode like a switch, and a diode is one of the most basic electrical items used in most EVERYTHING that has electronics - it lets electricity flow one way, but not the other.  

IMHO the best setup is two batteries and two electrical systems - one for the foo foo stuff like lights, stereo, coolers, etc - the other for the engine. These two systems powered off of a single alternator / isolator that will automagically charge the two batteries at the same time without affecting the other one. In this "perfect" system you also have a switch or high current relay that is normally in the off position but can be turned on to connect all batteries in an emergency. This is really handy if the engine bat is dead or dies and you need to start the engine (or if both batteries are near dead and that extra uomph will keep you from being a swimmer).

 





Title: Re: Second Battery
Post by: flytime on February 17, 2008, 08:07:41 PM
Yea, LOL . The ground cable looked a little small on the batt that had one  ;D.

Those are the grounds for the radio stuff. ;)
Title: Re: Second Battery
Post by: speedymopars on February 17, 2008, 08:16:13 PM
If you are curious to what size wire you really need to run - here are the standards.

http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
Title: Re: Second Battery
Post by: CHROMEY on February 18, 2008, 11:51:49 AM
also if your worried about some extra weight, you could always go with a great deepcycle battery, either a  odyssey or a kenetic, a range of compact sizes and amp hours you can mount them in any position leak proof,and take a beating and work great...in my opinion "optima" batteries suck, all of them red/yellow/even blue ones.....
Title: Re: Second Battery
Post by: crewchief22 on February 18, 2008, 12:54:35 PM
Optima use to be a good battery, but now that Johnson Controls has taken over just about every battery contract the quality has suffered.
Title: Re: Second Battery
Post by: UNDONE on February 18, 2008, 05:44:55 PM
Orbital batteries. Used them in everything I've had except my new boat and truck... Those batteries just havent gone bad yet...
When they do that's what they'll be replaced with. The orbital's did well rock crawling, off roading, in the mud. 900 CCA Orbital powered my headlights LED tach/speedo/gauges etc. engine for however long. Got me home, I was way out in the middle of nowhere. Next morning she started a little sluggish so I checked under the hood and sure enough, the positive lead had come off the battery! Had my radio on too.

Or one of these:
http://www.sonicelectronix.com/item_10461_Kinetik+KM27.html
SMFPacks CMS 1.0.3 © 2026