DUAL BATTERY INSTALL

[DaveK]

Dual battery install just finished (well not too long ago). I looked at the Wrangler NW set up and, although it’s good, it seemed to have some shortcomings. It uses two small batteries. It adds about 30 lbs. to the stock battery tray, which is just mounted to sheet metal. And, the hardware looked a little skimpy (for mounting about 80 lbs. worth of batteries).


Finding a mounting location for the second battery turned out to be easy. Its just not in the engine compartment. While some H2's have the air suspension option, every H2 has the brackets (or a portion of the brackets) and the holes in the frame to mount the air compressor for the air suspension. If you have the air suspension, this location may not work - you’ll have to check. Using the stock air suspension compressor location, (located just behind the rear axle pumpkin), I fabricated a platform and the necessary forward bracket. There was enough room on the surface of this platform to mount an ExtremeAire air compressor, http://www.extremeoutback.com/index.cgi and an Odyssey 1200 battery, http://www.odysseyfactory.com

Remote battery and air compressor on platform

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Remote battery and air compressor on platform

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Back in the engine compartment, the stock battery location was large enough to allow the use of an Odyssey 1700 as a main battery. I dumped the stock battery tray and fabricated another one and a hold down, to house the 1700. With this system, the 1700 had more juice than stock and was a much better battery. The 1200, when used as an emergency back up, was more than enough to crank the 6.0 if the main battery went dead. The system also allows both batteries to be used for high amp needs.

Main battery in new tray

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The isolator/combiner, by Hellroaring, http://www.hellroaring.com easily mounted in the engine compartment and the remote control tucked away nicely on the inside of the instrument cluster sun shade. From the drivers seat, a flick of the switch can change from the main battery to the backup battery to start the motor. In the remote’s center position, both batteries charge while driving. With the ignition off, the batteries are isolated and all accessories will be powered by the main battery.

Combiner/isolator

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Control switch

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[OLLIE]

Very nice install DTK... I like it. Odyssey is a great battery. I'm working on switching my secondary out to the Odyssey 1500. My primary is the PC1700 as well.

[OLLIE]

DTO makes excellent points here. I use solid state relays in my dual battery system as well. There is one more reason to avoid diode based isolators for the offfroad environment. Solid state relays are less prone to failure. Ask anyone who has had a dual battery system fail on them what the reason for failure was and I would bet that 95% of the time it was a diode that failed. Diodes burn out. I avoid diode based anything (other than radios) for my offroad equipment.

The only thing I have running off my main battery is my radios. all other accessories run of my secondary battery. I know A LOT of people run everything off their main battery and only use the secondary battery as a backup incase the main battery fails.

As DTO stated... Figure out what you want to use your Dual Battery for and plan accordingly.

[SteveS]

As DTO stated... Figure out what you want to use your Dual Battery for and plan accordingly.

That is a fact I think we’ll all agree on. No one set-up is the best.

Since you brought up the advantages about SSR’s I’d like to add this.

One big problem with the solid state relays (SSR) (in fact the #1 reason they are not used in sensitive systems) is the tendency to fail "shorted".

In a back country setting, on an overnight camp trip, this could be a bad situation.

I prefer the diode isolator and my current setup has lasted over 7 yrs and 90k miles. When they fail it’s easy to know, and deal with to get yourself back home, where repairs can be made.

IMO anyone running an SSR, should be carrying a fully charged jumper battery pack at the least. Heck everyone should carry one of these.

[DaveK]

I am always interested to find out what works best. After Daryl's post, I sent Hellroaring the information on my install and Daryl's comments, (some of which were over my head). His response, which I quote below, is interesting.

"Hello David,

Nice write up and install. There are many different approaches to the use of a second or more batteries. Yours is for a Backup battery application. The author of your response below clearly is not familiar with any of our products and is comparing (diode vs relay) to a different application with an RV focus. Our BIC's are more like a solid state relay with built-in control electronics. There are a few mis-assumptions below about charging such as a 10.5V battery will not stay at that level and accept much charge rate. At any decent charge rate, it is more likely to rise quickly to 11.5V or higher at the battery terminals. The figures stated also imply that diodes drop a constant 0.7V regardless of current through them. That is not so. They usually drop a lot more as current goes up. So, that throws off some of the calculations mentioned, and therefore, could change the conclusion. In any case, our BIC's operate differently (more like the relay method but automatically) and do not have any of the issues this author describes. Yours is not an RV application, and the BIC is not a standard relay nor a diode isolator. So, it is not accurate to conclude anything about your setup with details about the below described application.

Let me know if you have any more questions...
Best Regards,
Mike Hines
Hellroaring Technologies, inc.
P.O. Box 1521
Polson, MT 59860
406 883-3801
406 883-1174 fax
mikeh@hellroaring.com
http://www.hellroaring.com/" onclick="window.open(this.href);return false;"


All right, all you tech guys, nows the time to comment.

[SteveS]

I am always interested to find out what works best. After Daryl's post......

Which post is 'daryl's'? I don't see that name (handle), did I miss it somehow?

Thanks, and I'll try and follow along better in the future.

[DaveK]

I am always interested to find out what works best. After Daryl's post......

Which post is 'daryl's'? I don't see that name (handle), did I miss it somehow?

Thanks, and I'll try and follow along better in the future.

Sorry Steve. The post is missing and the break in continuity is our fault. At the risk of speaking for Daryl, I believe that he was mentioning the benefits of a continuous heavy duty relay over a SS type system that he viewed in my post. He brought up some interesting ideas and that is why I communicated with Hellroaring to get their take (which I posted).

[SteveS]

[ The post is missing and the break in continuity is our fault.

Thanks, that helps to know. Infact your reply is double helpful. I know I only have 4 or 5 postings, but yours is the only reply I got. I was wondering if there was phantom post list that only some saw, like maybe I couldn’t see Darrel’s, and nobody could see my posting.

[ .....benefits of a continuous heavy duty relay ......

For some applications the continuous relay is currently the absolute BEST devise to use.

Lucky for us vehicle modifiers we have many choices to fit the need(s) and technology offers more from time to time. The SSRs are showing up in more and more equipment here around at work, and they give us the capability to do things that maybe 10 +/- years ago where unheard of.