SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: bertus on March 31, 2009, 03:48:48 PM

Title: Installing dual batteries
Post by: bertus on March 31, 2009, 03:48:48 PM
How do you install another battery?  I am thinking about running possibly 3 batteries and wanna know how you install them and what you need to do it?  I am going to be running a mild stereo system and want to make sure that it wont drain my main battery.  thanks
Title: Re: Installing dual batteries
Post by: GT Jets on March 31, 2009, 07:45:09 PM
How do you install another battery?  I am thinking about running possibly 3 batteries and wanna know how you install them and what you need to do it?  I am going to be running a mild stereo system and want to make sure that it wont drain my main battery.  thanks

I'm going to give you the "golden goose fix", but can be done much less expensively, so bare with me...

First a question, why the hell do you need three batteries?   ???

You will need to think it through.

Figure out what you are trying to achieve, you always want a charged battery, so I highly recommend a battery isolator (not two), a battery isolator is a fancy name for a set of diodes. When you install the batteries use a battery switch, Marine preffered, but not required (may say the words "Vapor Proof"). Battery one (1) I always use for a starting battery (to each his own) this battery will be connected to battery switch terminal #1 and have one line from the isolator to that same terminal (#1), the next battery will be #2 and should be connected to the #2 terminal with the other side of the Isolator going to #2 of the switch, the middle terminal goes directly to the alternator charge wire..

Now, if you really want the third battery, the best way to do it is to use a constant duty relay on a switch at the dash and use it for the stereo only, the relay will charge the battery only when the switch is "on" and the engine is running, run a wire from battery #2 to the relay and from the other pole of the relay to the positive post of the #3 battery.

Then power up the relay using the ignition circuit to a dash mounted switch to the coil of the relay, this allows you to isolate two batteries from eachother (does not matter what position the switch is in to charge both batteries) and if you run the switch in #1, there will always be a "spare", charged battery, the third gets charged from the engine when the under way and is isolated from the engine when you want noise free tunes while idling alond (hence the switch)..

And there ya go!  You can link two batteries together, but I don't care for that method...

GT
Title: Re: Installing dual batteries
Post by: bertus on March 31, 2009, 08:10:22 PM
sweet!  thanks for the info.  I will probably only go with two batteries then.  Three sounds a little complicated.  I am just going to be running a couple amps and subs so just wanted to make sure i've got a battery to rely on for starting and running.
Title: Re: Installing dual batteries
Post by: jet boat performance on March 31, 2009, 08:42:54 PM
I'm going to give you the "golden goose fix", but can be done much less expensively, so bare with me...

First a question, why the hell do you need three batteries?   ???

You will need to think it through.

Figure out what you are trying to achieve, you always want a charged battery, so I highly recommend a battery isolator (not two), a battery isolator is a fancy name for a set of diodes. When you install the batteries use a battery switch, Marine preffered, but not required (may say the words "Vapor Proof"). Battery one (1) I always use for a starting battery (to each his own) this battery will be connected to battery switch terminal #1 and have one line from the isolator to that same terminal (#1), the next battery will be #2 and should be connected to the #2 terminal with the other side of the Isolator going to #2 of the switch, the middle terminal goes directly to the alternator charge wire..
  Whoa I think I need a smoke  ;)   Good tutorial !
Now, if you really want the third battery, the best way to do it is to use a constant duty relay on a switch at the dash and use it for the stereo only, the relay will charge the battery only when the switch is "on" and the engine is running, run a wire from battery #2 to the relay and from the other pole of the relay to the positive post of the #3 battery.

Then power up the relay using the ignition circuit to a dash mounted switch to the coil of the relay, this allows you to isolate two batteries from eachother (does not matter what position the switch is in to charge both batteries) and if you run the switch in #1, there will always be a "spare", charged battery, the third gets charged from the engine when the under way and is isolated from the engine when you want noise free tunes while idling alond (hence the switch)..

And there ya go!  You can link two batteries together, but I don't care for that method...

GT

Whoa Glenn ,I think I need a smoke  ;) Good tutorial !
Title: Re: Installing dual batteries
Post by: FORKEDUP on March 31, 2009, 09:00:25 PM
just for reference, I am running 2 large amps, head unit, cross over, 2  6x9 3 ways, 2 6x9 2ways, 2 6.5" full range, 2 1" tweets and 2 12" subs and using only 2 batteries, one for stereo and one for starting, hatch, bilge pump, blower etc.  there is enough stereo power to ripple the water >:D ;D and i have yet to have a problem, running a 2 position batt switch
Title: Re: Installing dual batteries
Post by: GT Jets on March 31, 2009, 09:14:01 PM
Whoa Glenn ,I think I need a smoke  ;) Good tutorial !

Thanks Tom!  ;)

GT
Title: Re: Installing dual batteries
Post by: bertus on March 31, 2009, 09:15:52 PM
okay sweet.  thanks for the info guys.  ill be installing another battery on thurs or friday along with the system.
Title: Re: Installing dual batteries
Post by: OC2Vegas on March 31, 2009, 09:18:46 PM
okay sweet.  thanks for the info guys.  ill be installing another battery on thurs or friday along with the system.

Dont forget the battery switcher

(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fwww.jamestowndistributors.com%2Fuserportal%2Fwoeimages%2F00006380.jpg&hash=045b65509fcd741968ebddc5ef958e4b1ee51e74)
SMFPacks CMS 1.0.3 © 2026