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post #1 of (permalink) Old 10-11-2000, 10:45 AM Thread Starter
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Jeep Dual Batteries

I do not have a dual battery setup on my YJ, but I was looking for a new isolator solenoid switch for my RV and I found these solid state isolators. The solid state isolators are said to be more dependable. I don't know if they would be a good choice for a Jeep dual battery setup or not, but they look neat.

My Jeep is a work in progress, Happy Trails
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post #2 of (permalink) Old 10-11-2000, 12:49 PM
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Re: Jeep Dual Batteries

You found the ticket!!
If you can get a good one cheap enough, have at it!

You still need some way to tie the batteries together if you need to jump start your self, but that's as easy as a second starter solenoid and toggle switch.

"I Have The Body Of A God... Buddha"
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post #3 of (permalink) Old 10-11-2000, 04:26 PM Thread Starter
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Re: Jeep Dual Batteries

The solid state isolators are about $ 65.00 for the 130amp model. This is at Camping World, they are usually high, you may find it for less.

My Jeep is a work in progress, Happy Trails
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post #4 of (permalink) Old 10-11-2000, 09:12 PM
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Re: Jeep Dual Batteries

Ive been running a dual optima battery set up with a solidstate isolator for a couple of years. It has held up well, with no problems to date.

89 Wrangler
I take my Jeep "On the Rocks",usually "With a Splash of Addrenalin"
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post #5 of (permalink) Old 10-11-2000, 09:58 PM
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Re: Jeep Dual Batteries

I know everyone thinks that I am beating this dual battery thing to death. But I still have a few questions. I hope that this will not be toooo much for the irritable old-timers.

So far, I can only see 2 reasons to isolate the batteries:
1. Cousin J. Bubba likes to pump the cd player, winch, lights, ect..without the engine running.
2. One weaker battery drains a stronger battery.

# 1 is easy. Take your keys. If you catch Cousin J. Bubba jacking around with your Jeep, slam his fingers in the hood. He will catch on.

# 2 is a little harder. How could you isolate the batteries so that a weaker battery could not drain a stronger one but yet they would still be fully functional at all times? I'll bet TR doesn't even know this one.


post #6 of (permalink) Old 10-12-2000, 12:23 AM
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Re: Jeep Dual Batteries

1. Don't sell TR short... he's forgotten knowledge on automotive systems tham most people on this forum have ever known....I'm good, damn good, but he's better... no bones about it.

2. Your question is one that has multiple answers... some simple and some not so simple... depending upon the way you look at the idea of what is meant by the term "fully functional." It's plain old Krichoff's Law that batteries obey that make them take on each others characteristics when they are not isolated. So to keep two good batteries in peak performace as long as possible... isolate them from one another.

Next comes the idea of the charge/discharge rate of the batteries... if isolated the batteries do not need to be the same. You can use one type for a starter battery and to run circuits on the Jeep, and a second type to run a winch or other high amperage equipment. It's another benefit of isolation.

If you choose to run two similar batteries it's best to charge and discharge them as equally as possible. To do this you could use the kiss system and use a manual connection switch... emergency vehicles use these all the time... as do marine applicaitons. Usally it's a mattter of running one day on one batttery and swithning to the second battery the next day. This keeps both batteries at as full a charge as they can handle as well as discharging them during the startand duty cylces. The system are inexpensive, and reliable.

Or you could use some pretty fancy electronic monitoring and swiching circuits that cost a small fortune to obtain and install that switches the loads to the most efficent use of charge and discharge charactericts of the batteries.

Or you could just use two batteries and connect them to the system on alternate days by physically hooking and unhooking them... that's the ultimate in cheap.

Then of course you can install a dual isolated system with the new voltage minders that cut out the battery when the charge capacity has dropped to a level just above the starting capacity of the vehicle. Use one on each battery.

How about solar trickle chargers for each battery... to keep them as fully charged as possible? That's a neat trick, but involved and you have to be an electronics geek to enjoy ginning up this system.

IMHO when you use an electronic isolator sytstem you increase reliabilty of the electroncics. With the engine running both batteries recieve a charge and accept the charge to the capacity of the battery... or it takes as much as it needs independent of the other battery in the vehicle. This is the optimum way to keep both batteries fully charged.

The next question is one of dividing up circuits (if you don't intend to alternate starting loads or heavy current applications like winching) By judicious engineering of the loads one should seek to balance the average amperage draw to equalize battery draw and charge.... opomizing the health of the battery.

Of couse we haven't even gotten to talk about the type of battery and which type is best for which load condition... that's another whole subject....

Good Jeepin'

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