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prostar205
12-26-2004, 11:22 PM
When installing dual batteries, is an isolator the way to go. In my opinion it is. This is the only way that I know of that will not allow each battery to drain the other. On my last boat ('95 PS 205), I installed dual batteries myself. I used an isolator to isolate the two batteries from one another so one did not discharge the other and also to allow the alternater to charge both batteries. I used a deep-cycle marine battery for the AUX battery and wired the stereo directly to the AUX battery. This way I could shut the engine off and still listen to the stereo all day.

Now, I understand the "new" of installing dual batteries is to just use a battery selector switch and no isolator. In this senerio, how does it prevent one battery from discharging the other once the second battery gets down to a certain voltage?

My goal is to be able to go out on the boat and turn the engine off and listen to music without having to way about having a dead battery at the end of the day.

Any help on this subject would be much appreciated. This is for a 2002 X30.

crdickey
12-27-2004, 12:21 AM
If it's wired in properly the selector switch isolates both batteries. You can select battery 1, battery 2, All or off. Same goes for charging.

Beware - Don't change selector to "off" while the engine is running, this can spike your alternator and damage your system.

When I'm running around the lake I have the selector set to "All".
When I'm anchored and running the stereo I select battery 1. I have the stereo wired to battery 1 and switched through the ignition accessory switch so I don't drain the battery with the key off. When it's time to start the boat I select "All". When "All" is selected the charging system charges both batteries. If you have 1 or 2 selected the charge goes only to the one selected.

OhioProstar
12-27-2004, 10:54 AM
I have two batteries on a switch as well. Basically I use the Aux battery as the starting backup if I drain the main. Normally I charge each battery prior to a long trip to the lake so I leave the selector on Bat1 most times. Someone on this board has a two bank charger that he plugs in every night which is what I will use next year. The switch and charger still costs less than a HellRoaring isolator.
http://www.overtons.com/cgi-bin/overtons/detail/pdetail2.cgi?r=detail_view&item_num=71445
http://www.onlinemarine.com/cgi-local/SoftCart.exe/online_superstore/electrical/blue_seas_battery_switches.htm?L+scstore+jpgt8160f f62c762+1104236559

crdickey
12-27-2004, 03:14 PM
I also use a "smart" trickle charger which I leave plugged in while the boats at home on the trailer. I also plug in a dehumidifier to help keep the boat dry.

Every time I launch the batt's are full and I have never had any mold or mildew or smell.

Diesel
12-27-2004, 04:11 PM
When installing dual batteries, is an isolator the way to go. In my opinion it is. This is the only way that I know of that will not allow each battery to drain the other. On my last boat ('95 PS 205), I installed dual batteries myself. I used an isolator to isolate the two batteries from one another so one did not discharge the other and also to allow the alternater to charge both batteries. I used a deep-cycle marine battery for the AUX battery and wired the stereo directly to the AUX battery. This way I could shut the engine off and still listen to the stereo all day.

Now, I understand the "new" of installing dual batteries is to just use a battery selector switch and no isolator. In this senerio, how does it prevent one battery from discharging the other once the second battery gets down to a certain voltage?

My goal is to be able to go out on the boat and turn the engine off and listen to music without having to way about having a dead battery at the end of the day.

Any help on this subject would be much appreciated. This is for a 2002 X30.

If you use a high current relay it will be completely automatic. I have mine wired to the ignition switch. When the boat is running (or the key to the right) the relay is energized (closed) and the two batteries are in parallel. With the key off or in the accessory position (to the left) the batteries are completely isolated(circuit open).

All my stereo componets are wired to the accessory battery to prevent my main battery from being drained. With a relay your key becomes the switch and you do not have to worry about it..............

milkmania
12-27-2004, 06:38 PM
Diesel,

Do you have a tutorial on this set-up?
I can do all the manual labor, it's just the hard brain stuff that hurts http://www.pcsympathy.com/modules/coppermine/albums/userpics/10002/banghead.gif


a tutorail would help me get all the parts and what I need to wire where:worthy:

OhioProstar
12-28-2004, 10:43 AM
http://www.hellroaring.com/simple.htm

Diesel
12-28-2004, 04:29 PM
Diesel,

Do you have a tutorial on this set-up?
I can do all the manual labor, it's just the hard brain stuff that hurts http://www.pcsympathy.com/modules/coppermine/albums/userpics/10002/banghead.gif


a tutorail would help me get all the parts and what I need to wire where:worthy:

Borg Warner makes the relay. Part# 3098R. You can find it any autoparts store. It has a 200amp continuous capacity. Around $20-25 bucks.

The wiring could not be easier.

Most dual battery installations are wired in parallel. In this configuration negative of main battery is connected to negative of aux battery and the positive of the main battery is connected to the positive of the aux battery.

This works fine in most automotive applications but does not work well for many reasons in the marine world. First the main goal here is to isolate the batteries so you always have a fresh battery for starting. Dual batteries wired in parallel act as one large 12 battery and if they are not isolated they will drain at the same rate leaving you stranded with two dead batteries. Second, dual batteries wired in parallel that are not constantly charged will eventually destroy each other as curent flows back and forth between each other. This was the main concept between dual battery isolators. They were large diode packs that allowed current only to flow in one direction which attempted to protect the aux battery.

In my system the high current relay serves the same purpose as the perko or manual switch the other members have mentioned. Except the relay is completely automatic and is controled by the ignition key.

Start by connecting the negative terminals of the two batteries with a 2 gauge battery cable (black to black). Next, the relay will be inserted between the positive terminals of both batteries. Two 2 guage jumper cables will have to be made that connect each of the batteries to the relay. In its natual state the relay is open. One terminal of relay activation circuit is grounded and the other is connected to the igntion circuit.

On my boat I was able to connect to the ignition circuit at the main engine harness near the circuit breaker at the rear of my motor. Just to be clear, this igniton circuit is only energized when the key is in the run position. It should not be energized when the key is in the accessory position.

In my system I have all my stereo equipment (except the head unit) running off the auxillary battery. When my key is in the acc position my starter battery is only being used to power the head unit. In addition when the key is off the batteries are isolated to prevent the batteries from destroying each other during the week or storage. Finally when the key is in the run position both batteries are connected and they are both charged by the alternator.

On other neat thing about this set up is if you leave something on like your running lights or blower overnight you still have your aux battery for starting. Even though the main battery is dead the relay kept the two isolated and once the key is turned to the on position you immediately get full power from the aux battery. It has saved my *** more than a few times..........

Here is a picture from the same setup in my jeep:
http://img61.exs.cx/img61/1382/dsc005391bb.jpg

Hope it helps :)
OD

OhioProstar
12-28-2004, 04:58 PM
Diesel where were you last year when I put my set up together. One thing to keep in mind is the alternator needs to be able to fully charge both batteries since the stock alternator is only around 50 amps you might get a partial charge. By choosing one battery at a time with a switch you can be sure of a full charge. Either way having two batteries is the way to go!

BTW Nice vette engine in that Jeep.

Ric
12-28-2004, 05:10 PM
Diesel, does that Jeep get DIRTY?

Diesel
12-28-2004, 05:10 PM
Diesel where were you last year when I put my set up together. One thing to keep in mind is the alternator needs to be able to fully charge both batteries since the stock alternator is only around 50 amps you might get a partial charge. By choosing one battery at a time with a switch you can be sure of a full charge. Either way having two batteries is the way to go!

BTW Nice vette engine in that Jeep.

Thanks for the compliments!! :D

I forgot to mention I did upgrade to a 160 amp alternator. I also ran 0 guage directly from the alternator to the main battery. My stock alternator was not doing the job, even with one battery.

OhioProstar
12-28-2004, 05:27 PM
So ProStar205 you probably have two options that work well.

1)4 Position Switch, a few lengths of 2/0 gauge wire, (8) 2 gauge lugs, and shrink wrap
2)A simple 200 amp Relay, similar wire, and an upgraded alternator, which also requires an upgrade to the master circuit breaker.

I spent quite a bit of my company's time determining which was better for me. The second option is the most fail safe in that you don't have to keep switching between batteries. The first option is relatively inexpensive and works as long as you keep the Aux battery charged up....hince this year purchase of a two bank trickle charger for me. Good luck.

Diesel
12-28-2004, 07:26 PM
Diesel, does that Jeep get DIRTY?

How about this............... :D

http://img78.exs.cx/img78/1005/9389.jpg

Ric
12-28-2004, 07:33 PM
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