lainez11

ok, so i was thinking i would really like a dual batt set-up??( http://project-jk.com/wp-gallery2.php?g2_itemId=117475 ) but would also want both batterys hook up to the jeep that way they both charge up... now before i get someone that tells me im retarded! im no expert, nuts and bolts i can do! wires and amps,watts etc gets alittle confusing? how would someone do this setup? would u really need a second alternator? i didnt think so if i remember correctly my old mans RV has like 3 batterys!! i think he said something about a regulater..? pertty much a switch so once batt #1 is fully charged then goes to batt # 2 right?
i figured this would be a great setup i know many of u guys out their run lots of lighs and winches, just think now with this bracket you could have a cleaner install!! part numbers, wiring diagrams, and prices would be a great help!!!! thanks in advance oh and this is my first post love this website!!

Vernnz

Do an internet search for ACR Automatic Charge Relay. They are used extensively in the boating and RV industries. Any boat store or RV store in your area can school you on them. They isolate the batteries when you shut down and connect them together when your engine is running. That way the second battery can be completely drained but the engine battery remains fully charged and ready to start.

Some have an "emergency parallel" feature. This is a switch that connects the two together with the engine shut off. If for some reason your engine battery dies you can basically jump start yourself from the "winch" battery.

Products run from $100 - $300. It just depends on how much you want to spend.

Big Clint

Painless Wiring makes a relay designed for switching from one battery to both, etc. I'm not familiar with how it all hooks up, but I did buy just the relay from them (250amp relay) and am using it on a switch to disconnect power from my winch when not in use...works great! I used it just like any other relay, but needed it to handle the draw of my winch which is rated about 210 amps.

In addition to your questions...what does a 2nd battery really gain you?

My thinking...Alternator puts out X amount of power. With everything ON, there is a drain that should not exceed the alternator. If power drain exceeds alternator output, then battery stores are used. 2nd battery would give you additional stores. So assuming lights, etc were on and the contant drain out-weighs the alternator output, the battery gets drained and the vehicle 'dies'? If the use of your winch puts you over that threshold, when the winch is ON, it is draining the battery, but when you let off the switch, the battery is charging. If your constant power drain exceeds your alternator output at all times, I would think you have a more serious problem.

Am I missing anything?

Atticka

Talk to these guys
hxxp://www.hellroaring.com/bic75300.php

They make a device called a battery isolator/combiner that will handle all of your dual battery needs (charge both from one alternator, combine both for more power or separate the two for different loads).

eDiveBuddy

First question you have to ask your self is why do you want dual batteries? When the answer to that is known then you can decide how to set it up.

If all you want is more amps, there is no need for isolators or switches. Just get two of the same batteries that are the same age (Read two new batteries) and connect them in parallel.

If you want to run two separate electrical systems then you need an isolator that can charge both batteries while keeping the loads separate.

If your electrical load is draining your batteries while the engine is running you need a bigger alternator and not more batteries.

There are more ways to hook up dual batteries and more reasons to do it. I have three batteries and a Hellroaring isolator.

Big Clint

Good info. Thanks for the link.

Any idea if 1 of those boxes could be mounted on the underside of the JK dual battery tray? There appears to be room there.

lainez11

hmmmm all very interesting... well the truth is i would most likley be fine with a winch and some off road lights on 1 battery, as many others do. but in my old Sonoma wiht just 4 100W kc lights as i turned on the 1st set was nice and bright but when all 4 lights on they all dimmed and really started to put a load on the system, you could watch the volt needle drop!!!( no i didnt install them)

Plus i would like to be prepared so to speak, even though i've never been stuck do to a dead batt. a Dual set-up would also be nice when out camping so the girlfriend can hookup her laptop, curling iron or whatever other Crap she cant go with out!!! but it would be nice like i said.

SO my question is what are the pros and cons of running batteries parallel, and seperate systems???

lainez11

oh and whats the correct way to connect the batteries parallel ?? did a search but no luck. so in parallel itl charges the batteries together ?

eDiveBuddy

If you are going to use a second battery for small thing with the engine off most of the time you'd want to run them separately. This way the Jeep has a battery all to itself and should not get drained from use while someones working on a laptop. Think of the house battery on a boat.

If you just want the amps for a boost for high draw amps with the engine running (winch) Then wiring them in parallel is all you really need. Draw back to this is if the batteries go dead, they are dead and you have two batteries needing to be charged. With two systems you have a chance, not a guarantee that one battery can be used to jump the other.

To wire them in parallel, positive goes to positive (+ to +) and negative goes to negative (- to -). When you connect it to the system, use a post from each battery. Wire from the alternator to one battery. Ground wire to the other. This helps keep the drain even across both batteries. If one battery is always draining off the other it's going to fail. This is the same reason to get two new batteries that are the same.

There is another option and that is to use the second battery solely as a backup to the first. This should guarantee you are always able to start your Jeep.

KingKoopa

Ok so before anyone says why or thats stupid, I have 4 Optima Batteries, two YellowTops under the hood and two BlueTops in the trunk. I have 8 Offroad lights and will be adding 6 more in August. I also have a Warn Winch and I love to blast the stereo and drive fast lol. that is why i have so many batteries. Now then. On May 18, I was going to the movies when my battery light comes on. I started thinking thats stupid cause I have 4 and a battery Isolator for them. Never the less, I wanted to go to the movies so i kept driving. Then all of a sudden, other lights came on such as, driver airbag, passenger airbag, ABS, traction control, emergency break, a lightning bolt, and one other that i forgot what it was. Then i said to my self, WTF. Then my Speedometer went from 60 straight to 0 (KM for you people, not Miles, I live in Canada) but my RPM's was still up there. Then my jeep stops and stalls in the middle of a road that only gets 30 cars a day (if that) so I jump start myself because I have the batteries. Worried, i take it to my dealership and leave it there for the rest of the day. The next morning they phone me and tell me that my alternator was dead so they ordered me a new one which is ok i guess. The next day they phone me again and said its in, and its not working...... I fried my PCM and that will take a week to get in. They also suggested to move up to a bigger alternator. The JK's all have a 120 amp alternator and the only one that they can offer is a 140 amp, its not the best but it will be good for now they said.
SOOO heres the main question for anyone that could help me. does anyone know where you can get a bigger alternator for the JK? preferably around 200 amps??????????