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Dual Battery Setup Help


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20 replies to this topic

#1 EOppegaard

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Posted 31 October 2003 - 11:14 AM

Well, I think it's time...I am going to tackle the second battery setup.

I would like to put an Optima Deep Cycle Battery into my 1993 Subaru Wagon in addition to my standard non-deep cycle cranking/starting battery.

I know that I will need to install some sort of battery isolator, and am wondering whether people reccommend the diode style, or an electronic style. Also, What size Deep Cycle Battery do people reccommend? I know that someone will respond "it depends on what you want to run and for how long" I know that, however I am looking for a real world situation of someone who has used the silly thing before!

I am putting in the Deep Cycle to help with current load when I am operating emergency lighting, and radio equipment for extended periods of time. I have noted a drop in performance and voltage when for example, its raining (wipers) its nightime (headlights, Driving Lights) its foggy, (fog lights) I am going to a call (Lightbar, Strobes, Siren, etc) and I need to talk on the radio (yeah, transmitting 100W takes a bit of power) ALL AT THE SAME TIME.

Yeah, I know this is a bit of a stress on the electrical system!

Thanks guys

#2 Legacy777

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Posted 31 October 2003 - 11:42 AM

just put an optima yellow top in and be done with it, there's no need for a dual battery setup.

If anything, I'd suggest a yellow top & higher output alternator.

#3 EOppegaard

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Posted 31 October 2003 - 11:46 AM

I replaced the alternator a while ago for a higher amperage one, one thing that I would like is having the added security of a second battery in case one were to crap out on me. The other reason is my other battery is not that old, figured I could just tack on a few more bucks for an isolator in addition to the battery and have a dual battery setup :banana:

#4 cookie

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Posted 31 October 2003 - 05:11 PM

there are a ton of options here. Just get an isolator that is rated higher than what you plan to draw through it.
I used to just double up my batteries when I lived in Maine.
Wire two sixes in parralell for a six volt system, or the same with twelves.
Then I started working on commercial equipment and found that trucks and busses had come to the same soloution.

#5 soobme

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Posted 31 October 2003 - 06:46 PM

I have run dualls for YEARS, and I have NEVER used an isolator. I just run the + cable from the 2nd one to the + on the 1st, and then run the - on the 2nd to the engine block. Has yet to ever let me down, and thats with running a WARN 8000lb winch with the engine off for long enough to kick the thermal protector on the winch!
If U do use the isolator, I would go with 150-200amp electronic unit. And up-grade all your battery cables to 4ga. welding cable(it's the best stuff I have EVER found for batt. cables!)

#6 EOppegaard

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Posted 31 October 2003 - 07:03 PM

Yep, I need an isolator though since I am mixing a deep cycle with a regular starting battery, hence batteries of different type and age.

#7 Qman

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Posted 31 October 2003 - 11:34 PM

Here's a pic of my set up.
Pic

I used an RV isolator. It's wired to switch on when the key is in the ignition mode. I have a standard wet cell starting battery and my winch and welder run off the dry cell. I got it at Les Schwab. It's the RV/marine.

#8 MilesFox

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Posted 01 November 2003 - 12:21 AM

on my 83 wagon with the ea82 engine, i put the battery and coil on the other side of the car. my original battery, on the opposite side, was connected to the starter cable and engine ground cable.

the extra battery, in the CAR's original location, was connected to the fusible link block. it grounded to the body ground (both terminals on the original battery clamps)the alternator was still connected as usual.

everything worked like it was supposed to. but every now and then the voltage would kick up to 18, and i had to turn the key off, then back on to restore proper voltage.

having 2 batteries connected as such probably overdrew the alt, confusing the voltage regulator. its not that i had a lot of amp draw, but another battery can pull some amps off the alt to keep it up, x2

all the voltage spikes went away when i removed the extra bettery(from the fuse link side

#9 EOppegaard

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Posted 01 November 2003 - 12:26 AM

Fox, by coil do you mean battery isolator? If not that could have a reason to do with your voltage spikes. If the batteries are of different types, and the alternator is charging both, it will confuse the voltage regulator. :cornfuzz:

#10 MilesFox

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Posted 01 November 2003 - 02:16 AM

i meant ign coil. they were both starting batteries, one interstate, and the other some duralast or wal-mart brand.

maybe the way it was grounded had something to do with it. it might have not been a parallel connection the way i had it.

i was for a little bit running a spare battery in the car with jumper cables to the main. i dont recall voltage spikes then. but it was good year ago at least.............

#11 Ranger83

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Posted 02 November 2003 - 07:51 AM

From another forum:

Many people are under the impression that adding a second battery will cure their electrical problems. If one battery is good then two must be better. Right? Wrong. Remember that the function of a battery is to start the vehicle and to provide power when the vehicle is not running. The only thing a second battery will help you with is providing additional capacity without starting the vehicle. After the vehicle is started the second battery becomes another load on an already overworked alternator. If you do replace your battery I would recommend getting one from Optima


You have higher output from the alternator, why not just get an AGM battery? I see that they're starting to hit automotive store shelves, but you can find them in most marine stores. Or add a power capacitor?

Where are you going to put it? Locating a 45 lb plastic box full of acid in the front of the car doesn't seem like that good an idea.

I'd go to an RV shop, they deal with such systems all the time. Or a high end car audio shop.

Or adopt the simple approach my friends in Alaska take. They keep a second battery in a plastic battery box bolted to a piece of plywood in the back of their OB. They can trickle charge it from the rear outlet, but usually bring it in to charge it. It's simple, it's there, and they can bring it inside when it's very cold out to help jump their car the next morning. It's also 45 lbs right over the rear wheels. This gives you the backup battery but does not solve the power problem you have.

#12 EOppegaard

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Posted 02 November 2003 - 11:48 AM

I knew that this post would bring about a lot of different ideas, and some people who think my idea is just plain stupid. However to just be blunt, I would like a second battery in the car. Yes, you may all be right, that I could just replace the current battery, or get an even higher output alternator, however I don't want to. I have put in a higher alternator, all I want to do now is have more reserve capacity power. Having the additional battery to run the accessories will also put peace of mind that my car still has another battery to start.

Ohh, and I am not too crazy about mounting a "45 pound block of acid" to a piece of plywood in the back of my car.

:D

#13 Ranger83

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Posted 02 November 2003 - 05:54 PM

I have put in a higher alternator, all I want to do now is have more reserve capacity power.



Then you need a power capacitor, not another battery. Also known as a stiffening capacitor, and routinely used by audiophiles who like to make their cars vibrate.

I'm not sure if ham operators or others with high powered temporary output demands find them necessary.

#14 Snowman

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Posted 02 November 2003 - 08:02 PM

Q Man, what is your exhaust pipe doing way up there in that picture? Would I be right in assuming it's for better clearance, or is it some magical thing that appeases the internal combustion gods?

#15 CaptainT

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Posted 02 November 2003 - 09:47 PM

Oppie,
I have some experience in design of emergency warning systems for emergency response vehicles, and I thought I would pass on some of the things I have picked up over the years. First, in no way, ever, should warning equipment be attached to the factory wiring harness of the vehicle being modified.

Specifically, vehicles that fall under the umbrella of NFPA oversight shall have a warning system that is “Stand alone” except for the connection to the charging system. Because you are a volunteer firefighter and the vehicle is private, than obviously this does not apply. Most states have very specific laws about the amount of light discharged as to achieve the adequate amount of light at the right distance. It absolutely is not a case of adding strobe packs and LED’s until it “looks cool”.

Keep this in mind Oppie, because the vehicle is private, any modifications you make to the vehicle that are used in warning other drivers that you are operating in an “official capacity” (of any kind) and requesting the right of way, is your responsibility alone. Should an accident occur while you are responding to an emergency, and fault is determined to be yours, then the liability will be yours alone, not the agency you work for, or even your personal insurance. To my knowledge, no insurance company will insure for use a private vehicle that is operated in an “emergency response capacity”.

That being said, my advice to you would be to restore the factory harness to OEM specs, install the appropriate heavy gauge supply wire to an isolation solenoid, and pursue the Optima deep cell you spoke of.

I admire your service as a volunteer firefighter; often this is the only fire service a community has. I myself was a volunteer for seven years before attaining a job at a full time agency, but please be careful, your service will be in vain if someone is injured because of well intentioned over zealousness. ;)

Best of luck,
Tom
:santa:

#16 EOppegaard

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Posted 02 November 2003 - 10:47 PM

You are correct that most states do have laws regulating the use of blue lights for personal fire vehicles. However, the State of Connecticut, the state in which I operate, does not have any such laws regulating blue lights. There are no laws regulating the use of blue lights on personal vehicles. It only states that the light you use shall be blue.

As far as restoring the vehicle back to OEM standards...well, the system is pretty much standalone, with the exception of the battery. No modification has been done to the power system of the vehicle, with the exception of adding a higher output alternator.

The vehicle has been equipped with a second, stand alone breakout panel, wired directly from the battery, complete with its own set of fuses and/or breakers. If this system were to fail, the vehicle would continue to operate normally, since the vehicle system is not dependent on the circuts the accessories use.

Is this more of what you were searching for? Or am I still missing something here?

If you have another reccomendation, or concern about this type of wiring, please feel free to let me know. It has not failed me yet, however I am always open to reccomendations!

Thanks for your concern, i'm glad to know there are other emergency buffs out there on the board!

#17 subie83

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Posted 07 November 2003 - 05:45 PM

Get a Stiffing capacator. It will help run the accessories for a good 45min until it begins to die out. Ham Radio Peps use them all the time, you should know that!

#18 EOppegaard

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Posted 07 November 2003 - 05:47 PM

Subie, I believe you to be incorrect. That will only help run the accessories for about 1 second before it will need to be recharged. A capacitor is only good for short bursts of energy, not long term operation. If the capacitor was the size of a small u-haul...then it may help.

#19 EdgeFire

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Posted 07 November 2003 - 08:54 PM

Originally posted by subie83
Get a Stiffing capacator. It will help run the accessories for a good 45min until it begins to die out. Ham Radio Peps use them all the time, you should know that!



Hmmm. No.

#20 paladin_w

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Posted 08 November 2003 - 11:39 AM

Oh to only have the room to install a secondary. I know there was a post that said a second battery was only a load after the vehicle was started...and that is correct...kind of...if everything is running of standard OEM with primary circuitry running off of fuses. However when you are running a lot of extras and they are hooked up direct batt line, like large stereos that uses the extra amps the batt has to make up the demand espically on bass hits. When the demand is not there the battery will act as another load.
I had a dual batt in three of my vehicles including my 92 sub, and wish I could have a secondary in my 97 but there is no room. For others reading this post if you want a backup batt for peace of mind just incase the primary fails, just wire up a second if you have a place with the same size gage the primary has - to block and one end of + to primary batt, and install a large coverable throw switch available at most auto stores, looks like a bar that slides into two tongs. Then if your primary batt dies all you have to do is pop the hood throw the switch, watch out for a little spark, do it quickly, and give the other batt about a min to give the primary a little juice then you have jumped your car with itself! :headbang:

#21 WoodsWagon

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Posted 03 May 2004 - 07:25 PM

I assume that you are installing the 2nd battery over by where the turbo setup would be. I'm planning on doing the same paralell install. I was just wondering if there was a better placefor the battery.




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