Dual battery

[Clark White]

I'm looking into a dual battery setup (maby a triple battery?), and came across this link from Baja Overland. http://www.bajaoverland.com/dualbats.php How does that work with charging both battery's while not letting one drain the other?do you have them tied when driving, and then when you stop you untie them? Also, I have the room for a third battery. Right now I don't have the need, but I could see down the road when I have a fridge and other power hungry toys needing a third (one starting, two aux). Anyone found this to be a need?

Thanks!

 

[adrenaline503]

Glad you asked this, I was wondering too. I always prefer simple when it comes to electrics.

 

[Grim Reaper]

That is just a switch to gang the batteries together. It is totally manual in operation the way it is wired. To make it automatically charge both batteries you would need something like this modual linked below. Or a Battery Isolator. Battery Isolators have some loss where is the part linked has a solenoid and eliminates the voltage drop.

http://www.westmarine.com/webapp/wc...rue&storeNum=5002&subdeptNum=9&classNum=12106


If you are wanting the ability to gang for a high draw item like a winch then you would want to use the big manul switch becaseu it can handled the higher draw. The item linked would not stand up to that kind of draw.

 

[madizell]

How does that work with charging both battery's while not letting one drain the other?do you have them tied when driving, and then when you stop you untie them?

There are two schools of thought on multiple battery installations. You can directly tie two or more batteries, either with permanent wiring or with heavy duty switches, or you can isolate each battery with a battery isolator, which I believe includes the use of a diode, or one-way electronic bridge.

If tied together without an isolator, both batteries are charged or provide power simultaneously, effectively doubling your reserve capacity. Isolated batteries provide isolated power until switched together, then they act the same as batteries which are merely tied together with cables.

I have been using dual Optima batteries for about 7 years without isolation. In that time, I have had one battery failure. While there is a potential for "dueling battery syndrome" if two or more are simply ganged together, I have not experienced such a problem, always starting with two identical and new batteries. I also don't have dead battery issues from leaving them ganged and parked for long periods. The Jeep is parked more than it is used, and having batteries ganged together does not appear to be an issue.

On the other hand, because of the electrical demands of winching, I have always been leery of using an isolator because of their duty rating. Most use 200 amp components. My winch draws far more than that, and the alternator makes more than that, so I have never tried isolators and switches.

 

[crawler#976]

I decided to go with a simple isolator from SurePower. So far so good...

http://www.surepower.com/isolator.html

The cost of a combiner/isolator was a bit steep when added to the cost of a 950CCA deep cycle battery, the materials to build a mount, 25' of 2 gage cable, a terminal crimper, shrink tubing, and 3/8" crimp on ring terminals. I spent nearly $500.00 to get the truck setup for a winch. The battery was 2 bucks, the isolator and install kit was a buck and a quarter, the 2 gage cable cost a few bucks a foot, etc, etc, etc...

http://expeditionportal.com/forum/showthread.php?t=9994&highlight=battery

 

[Tucson T4R]

X2 The Surepower Separator is the one I installed about a year ago. So far so good. I like it. It's primary function is to monitor your primary battery and protect it from being drawn down too low. It will olny connect the two batteries if the primary is healthy unless you use the manual override switch to give yourself a jump when the primary is too low to start your rig.

http://www.surepower.com/separator.html

 

[robert j. yates]

I'm one of the ones' using an isolator and I have no issues with it. The isolator is rated correctly, the battery cables are upsized and I have installed a Mechman 220amp alternator with 1O cabling to ensure optimum charging in any condition. I am also using a 500amp inline fuse on my winch circuit and dual Odyssey PC1200 batteries to complete the system.

For your reference, here is the kit I am using along with a write-up on the install into a Jeep Wrangler TJ.

http://www.kodiakinc.com/dual_battery.html

http://www.stu-offroad.com/electrical/kodiak/kodiak-1.htm

 

[ntsqd]

I've used an isolator. I didn't like the voltage drop & didn't know that I could have the voltage regulator tweaked to offset the voltage for the drop. As a result neither battery ever really got completely charged.

I have the marine combiner switch on a GM OE dual battery vehicle. It came stock with the batteries in parallel, nothing else in the circuit. I put the current set of batteries in the truck (same battery, same time, same vendor) and they appear to have "aged" faster than I find acceptable. One is near the end of it's service life in 4 years of mostly sitting. I suspect this is due to a combo of what the batteries are and the way they are wired.

The ACR ("Automatic Charge Relay") that Grim linked looks like a better deal to me. A 'smart isolator' that senses when the alternator is charging and turns on a solid state relay that has no voltage drop sounds like a winning idea to me. I wondered why something like this wasn't available when I installed the isolator in '89. I expect that these will eventually obsolete diode bridge isolators for most applications.

 

[Clark White]

Thank you all for your input! I'm not that familiar with vehicle electrical, so I know almost nothing about the options available.

 

[pete.wilson]

Hey

Does anyone remember with the diesel suburbans; do they use an isolator with them or just run both batteries in parallel? The isolator would only be needed if the alternator will be used to charge both batteries and keeping them seperated during starts.

 

[dallasrover]

X2 The Surepower Separator is the one I installed about a year ago. So far so good. I like it. It's primary function is to monitor your primary battery and protect it from being drawn down too low. It will olny connect the two batteries if the primary is healthy unless you use the manual override switch to give yourself a jump when the primary is too low to start your rig.

http://www.surepower.com/separator.html

Which Surepower part number did you use? Reading their information, they sound like a reasonable option. Sounds like the Bi-Directional one gives you option of using your backup to assist with starting if needed.

Thanks

 

[ntsqd]

If my gasser Suburbans ('79 & '91) are any indication, then they are directly paralleled, no isolator of any sort.
A friend went through UTI with the diesel option in the early 80's. What I recall from talking to him long ago about those GM diesels supports this.

Not conclusive, I know. Perhaps someone else has more direct info.

Hey

Does anyone remember with the diesel suburbans; do they use an isolator with them or just run both batteries in parallel? The isolator would only be needed if the alternator will be used to charge both batteries and keeping them seperated during starts.

 

[Maximus Ram]

Like other, I am researching this subject. For my Dodge, I have heard I can find the diesel equivelant and scavange the set up from it .....but the XJ is going to be more of a challenge because of the space under the hood.
So far there is some good info here.......thanks

 

[Nitromethane43]

Hey

Does anyone remember with the diesel suburbans; do they use an isolator with them or just run both batteries in parallel? The isolator would only be needed if the alternator will be used to charge both batteries and keeping them seperated during starts.

All the light truck diesels are wired parallel from the factory without any isolation devices, they have a dual battery setup to meet the CCA's needs of a diesel.

A great isolation device is the Powergate as it allows charging without any noticeable voltage drop compared to battery isolators, and it is automatic saving the hassle of manually switching. http://www.perfectswitch.com/whypgate.htm

 

[KodiaK Commando]

I love my Surepower separator. We started using them at Sportsmobile about 2 years ago and the only issue that I have heard of is when there is a ground issue it won't switch. That's a maintenence issue no matter what you connect with. Our old motorhome had something kind of similar. Fleetwood just added a solenoid between the two batteries. When the ignitian is off, the solenoid is disconnected and therefore the batteries are separated. When the ignition is on, the solenoid is engaged and both batteries get a charge. The Surepower separator is just a fancier version of that in that it senses voltage and automatically switches when needed.