I'm going to be getting the Benchmark stage 3 dual battery set up, but have a question regarding my batteries.

I have 2 new batteries: an Optima Yellow top and a standard Duralast (Duralast replaced a Blue top that died on the trail).

Which battery should I hook up as the main starting battery and which should I use for accessories. I have a 10K winch, lots of lights, Ham & CB radios, plus usually run with 2-3 GPS's, so in other words lots of accessories.

 

I would use the optima as the auxiliary, especially being that you are going to run a winch off of it. Many posts here about oem batteries crapping out prematurely, even with out the extra draw from a winch or other accesories. I have the Benchmark dual battery setup with the Smart isolator, and 2 Diehard Marine deep cycle batteries, but if I only had one it would be to run the auxiliaries.

 

Totally Agree ... plus if you hook up the boost wire and your oem battery has troubles you can jump start yourself if needed ....

 

Bravo Zulu guys, that is exactly right you want the deep cycle batt to be the one that carries the load when the engine is not running. A normal starting batt won't last long if it is drained down low on a regular basis and even the stock radio in todays autos will kill a batt in a very short time if you are sitting there with the engine off listening to the tunes.

 

Thanks for the feedback, that's what I thought, but wanted to make sure I wasn't getting it turned around.

 

Benchmark recommends using the same type of battery for both. They are also supposed to be manufactured around the same time. I put two Yellow top's in mine.

 

There is no reason to have both batts matching if you are using an isolator. If you are going to the trouble of having matching batts then just hook them up like on a diesel truck so they are both always working together and save some money.

 

The isolator isolates the batteries when the Jeep is off and the power is being drained. However, the charging system is the same one charging both. Electricity is like water. It will always try to equalize. The isolator is not isolating when the charging system is activated. It doesn't switch between the two. The smart isolator will get the main up to 80% or so and then introduce the Aux, which will force the alternator to push max Amps until it is charged. The main battery will also try to flow out to the Aux until they are at the same level. This process can overheat the weaker battery and could cause issues with the electrical system.

Personally, I would go with what Benchmark says to do. It doesn't make since to me to go through all of the work to install two batteries, isolator, etc. to cut a corner to save a few bucks.

 

Most people run matching batteries (dual odyssey's or optima yellow tops) mostly because there's no reason not to. Reusing the stock battery in the starting position is generally a bad idea because they tend to die quickly in any configuration (single or dual battery applications).

Running mismatched batteries is generally only a problem when the batteries are hardwired together in parallel.

 

Just to clarify, this is not the stock battery I have, my Optima Blue top died on the trail last week, 2.5 hours from civilization. The guy I was weeling with drove in and picked up a new battery from Auto Zone. I took my Blue Top in for warranty replacement when I got back into town, so I have 2 new batteries and want to run a dual battery set up.

I can't bring my self to spend another $160 on top of the cost of the dual battery set up, the cost of the Auto Zone battery ($100) and the cost for the warranty replacement (was in the prorated perios, cost $100).

If anyone can provide me a reason why I can't/shouldn't run two of the same size batteries (just different quality) please let me know.