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Old 02-05-2019, 03:43 PM   #1 (permalink)
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dual battery setup

Seeinz that I can't find a search function on the forum I'll just ask.

who's running a dual battery set up?

parallel with a isolator or series to up your amp hours?

give me your $.02
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Old 02-05-2019, 05:02 PM   #2 (permalink)
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Old 02-05-2019, 05:31 PM   #3 (permalink)
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Just learned this last night.

"Go to google and type "site: pirate4x4.com" after your search critera. For example:

"dual battery: pirate4x4.com"

April 2019 Petersen's 4Wheel & Off-Road mag has a dual battery tech article.
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Old 02-06-2019, 01:52 AM   #4 (permalink)
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people with audio systems have been running dual batteries for decades

so I ask, why do you want that kind of setup? do you have a big stereo?

I dont see the need for dual batteries in most offroad vehicles.. unless your running some serious lights..

and even then, I would say an aftermarket high output alternator.. would be better
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Old 02-06-2019, 07:25 AM   #5 (permalink)
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Quote:
Originally Posted by ArTi54N View Post
people with audio systems have been running dual batteries for decades

so I ask, why do you want that kind of setup? do you have a big stereo?

I dont see the need for dual batteries in most offroad vehicles.. unless your running some serious lights..

and even then, I would say an aftermarket high output alternator.. would be better

multitude of equipment, lights , chargers , gps, cb, winch, compressor and ARB fridge/freezer . A larger alternator wont do what I need. I was looking for input on people who are already running and what set up they were running. series set up has some advantages over the isolator set up, just wondering peoples thoughts who have run either. My battery goes dead in two days just with the residual current draws I have.
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Old 02-06-2019, 07:57 AM   #6 (permalink)
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Does the OP (Leeroy) want twice the amperage or twice the voltage.

One of my CUCV M1031 trucks has the 24 v starter with the resistor pack to lower the voltage in the cab where things are 12v.

My 07 Chevrolet Silverado classic has 2 red top optimas but in parallel.

ETA: Both trucks have two alternators with isolated grounds.
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Old 02-06-2019, 08:59 AM   #7 (permalink)
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Rockhound Installs Dual Batteries & IBS Relay in Our Old Ford
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Old 02-06-2019, 09:03 AM   #8 (permalink)
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Originally Posted by ParadiseAutoElectric View Post
Does the OP (Leeroy) want twice the amperage or twice the voltage.

One of my CUCV M1031 trucks has the 24 v starter with the resistor pack to lower the voltage in the cab where things are 12v.

My 07 Chevrolet Silverado classic has 2 red top optimas but in parallel.
leave it a 12v, but maybe a better amp capacity. I see the isolator as a benefit as my starter battery will always have power. then run all acc off the second battery, but the two with out isolator could be good as the amp hour increase would be better for the winch use and fridge, Maybe? just trying to weigh my options before dumping money into two batteries and the isolator.
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Old 02-06-2019, 12:47 PM   #9 (permalink)
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Run 2,your primarily starting/truck batt and a 2nd for all your shit
Or like mine
I have 1 big one for everything and a smaller one with nothing hooked up to it unless im running,starting or have the backup switch flipped both batteries are isolated
$12 200amp solenoid and a 20amp 3 ways switch
Switch is wired
On with ign (run and start)
Off if I want to pull the 2nd battery for any reason
On with 12v fed from the 2nd battery incase I kill the main battery
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Old 02-07-2019, 09:00 AM   #10 (permalink)
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There are different configurations of running dual batteries. With or without isolator, etc. None of them are run in series unless you are running a 24V system such as military or heavy truck.
Running batteries in series adds the voltage of the 2 batteries together while keeping the amp hour rating the same.
Running batteries in parallel adds the amp hour rating of the two batteries while keeping voltage the same.
Running your 12V vehicle on 24V will let all the smoke out of the wires.
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Old 02-07-2019, 10:30 AM   #11 (permalink)
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I run a dual battery in parallel setup.

Simple 200 amp continuous duty relay activated by ign power ties them together. Fancy isolators not needed imho. At least for my application.
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Old 02-07-2019, 10:46 AM   #12 (permalink)
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My battery goes dead in two days just with the residual current draws I have.
Fix whatever is drawing your battery down rather than adding another battery. What you're saying is equal to having a slow tire leak and trying to put duals on to fix it. Sounds retarded when you put it that way.
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Old 02-07-2019, 10:55 AM   #13 (permalink)
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Does not let all of the smoke out only the bad smoke.

Beyond that 24vdc is more efficient than 12vdc just build a system like the CHEVY CUCV.


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There are different configurations of running dual batteries. With or without isolator, etc. None of them are run in series unless you are running a 24V system such as military or heavy truck.
Running batteries in series adds the voltage of the 2 batteries together while keeping the amp hour rating the same.
Running batteries in parallel adds the amp hour rating of the two batteries while keeping voltage the same.
Running your 12V vehicle on 24V will let all the smoke out of the wires.
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Old 02-07-2019, 12:04 PM   #14 (permalink)
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Fix whatever is drawing your battery down rather than adding another battery. What you're saying is equal to having a slow tire leak and trying to put duals on to fix it. Sounds retarded when you put it that way.
Not even close to the same as a slow leak in a tire. If you require a larger payload you upgrade to a heavier suspension/dually, you don't stop hauling your stuff cause that's the fix. All electronics have a residual draw, especially on the newer vehicles with all the modules associated. When you have a large amount of stuff it adds up. Although the fridge/freezer is a large portion of the draw on the summer.
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Old 02-07-2019, 12:58 PM   #15 (permalink)
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Not even close to the same as a slow leak in a tire. If you require a larger payload you upgrade to a heavier suspension/dually, you don't stop hauling your stuff cause that's the fix. Hauling? WTF? You battery doesn't stay charged, keep up.All electronics have a residual draw, especially on the newer vehicles with all the modules associated. Sure, but not enough to drain a battery in 2 days. When you have a large amount of stuff it adds up. Although the fridge/freezer is a large portion of the draw on the summer.
I get the fridge being a big draw, if that kills it in 2 days, sound quicker than it should, but I'll buy it. The rest of the stuff (from your list: lights , chargers , gps, cb, winch, compressor and ARB fridge/freezer) you're not running the lights, GPS, winch, compressor, and probably not the CB while the unnamed vehicle is question isn't running, and shouldn't contribute to a residual draw that kills the battery in short time.

Either way, this has been covered to death on the internet and beyond. Simple option I didn't see listed is 2nd battery connected to the main battery with a solenoid inbetween. Solenoid wired to only let power pass between batteries while the vehicle key is on. Wire fridge and whatever else to 2nd battery so that the main battery will still start the vehicle.

BUT if you have some parasitic draw killing the battery, then it really wont solve that.
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Old 02-07-2019, 03:20 PM   #16 (permalink)
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Does not let all of the smoke out only the bad smoke.

Beyond that 24vdc is more efficient than 12vdc just build a system like the CHEVY CUCV.
Going by your screen name I believe you know what you are talking about. What I was trying to tell the original poster was that if you put 2 batteries in series, in a vehicle with a 12V system, you will be doubling the voltage to 24V....not doubling the reserve capacity. Many, if not all, of the 12V components in the vehicle that are not made to handle 24V could/would fry.

Switching to a 24V system might be more efficient, but it would involve switching to an actual 24V system...not simply running two 12V batteries in series.
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Old 02-07-2019, 03:31 PM   #17 (permalink)
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Some components can handle the voltage range but most can't.

In the CUCV trucks there is a large pair of resistors just behind where the distributor would be on a BBC or SBC engine truck.

It drops the voltage down to the area where most stock components can handle.

I equate this to the same reason the cross country high tension lines are 250Kv and up Its more efficient to send voltage long distances with a higher voltage as it keeps the power company from having to use a thicker wire and in turn more towers to support the larger diameter wire.

A company called roscommon has a CUCV conversion article to assist one from using the stock 24v CUCV wiring system, one could download thar PDF and reverse the process to get the 24 v starter setup out of their existing 12v system.






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Many, if not all, of the 12V components in the vehicle that are not made to handle 24V could/would fry.

Switching to a 24V system might be more efficient, but it would involve switching to an actual 24V system...not simply running two 12V batteries in series.
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Old 02-12-2019, 11:55 AM   #18 (permalink)
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I run two in parallel. It a simple easy way to increase overall capacity.

Was ready to buy a fancy Optima or whatever for my CJ, then realized I could get a dual battery tray and two marine starting batteries for less than one optima.

Recently did the same thing in my suburban. I like that they provide more of a buffer for vehicles that sit a long time, or if you do something stupid like leave the light on, or if you want to listen to music when camping without starting the vehicle.
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Old 02-12-2019, 01:11 PM   #19 (permalink)
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I went an unconventional route, I've got two completely separate systems with two alternators. Run all the auxilary stuff off one and the vehicle itself of the primary. To parallel them I have constant duty solenoid wired between the positive terminals, flip a switch and double my capacity/charging or I can use it to self jump start from in the cab. Been working perfectly for over a decade.
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Old 02-20-2019, 07:55 PM   #20 (permalink)
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dual battery

You the cables in a parallel circuit, it is ideal many for the winch, sometimes you might not have the rig running. You do not need an isolator for dual batteries. Run 2 12 volt gel deep cycle batteries so you can leave your lights on if you need to, the deep cycle batteries can take more abuse. Plus if you roll over you don't have to worry about acid leaking.
The parallel circuit is positive to positive and negative to negative, its the same setup you would use for RV trailers. Do not run a 24volt system.
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