Dual Battery and Compressor Install

[DaveK]

Several years ago I made and installed a dual battery and air compressor platform on the H2. The reason for this post is the recent addition of a recessed air compressor connector on the rear bumper. Before I settled on my set-up, I looked at the Wrangler NW dual battery system 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. of batteries.) No offense to them, but I've had too many things wiggle lose or break and I wanted to avoid another problem, if possible.

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 the platform to mount an ExtremeAire air compressor, and an Odyssey 1200 battery.

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 a much stronger stainless steel one and a hold down, to house the 1700. With this system, the 1700 had more juice and was a much better battery than stock and 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.

The isolator/combiner, by Hellroaring, easily mounted in the engine compartment and the remote control tucked away nicely on the inside of the instrument cluster sun shade (note: the old Nextel cell in the picture). 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.

Initially I had the air compressor mounted so that the connector stuck out from the bumper by about 2-3 inches. I was never completely satisfied with this, in fear that something on the trail would rip it off. Solution - I recessed the connector and now its safe from almost any trail hazard. Altogether, this set-up has been working now for over 6 years and not a single breakdown or failure.

 

[SuperBuickGuy]

I like.... dual batteries is my next update

 

[cbetts]

I am about ready to upgrade my OBA. I am tempted to put the compressor in the rear but I like to go mudding occasionally.

 

[RamRod]

I dig it!

Cool set up!

With the 2nd battery so far back are you worried about loosing (have you) a bunch of efficiency?

 

[SuperBuickGuy]

I am about ready to upgrade my OBA. I am tempted to put the compressor in the rear but I like to go mudding occasionally.

I mud, and I have dual viair compressors underneath.... they don't get muddy because they're pretty protected by the under-skid plate and because it's right behind the rearmost cross member

 

[DaveK]

1. Ramrod - That was a big concern as I selected the components for the set-up. DC applications are very sensitive to long runs of cable and the longer the distance, the greater the need for bigger cables (to prevent loss). Its been a few years since I did the original install so some of the specifics of the installation have faded, but I do recall that I spent considerable time consulting wire gauge charts and discussing the set-up with Hellroaring. The net result, given the cable runs involved, was the use of 000 gauge cables with heavy duty crimp-on marine connectors. I haven't put an analyzer on the set-up to see how it is performing, but in 6+ years, the backup battery has been used on several occasions to jump start a dead battery and give me some extra juice for the various radios in the truck, all without a problem.

2. Craig - I'm not fond of intentionally driving into mud, but it seems sometimes it is unavoidable. As much as I try to avoid mud, I cannot avoid dirt and dust. Over the years, the AC has been exposed to both, with not a single problem. If you look at the picture of the air filter on the air compressor, you will see that it is the same type as used on dirt bikes (in fact it uses the same type of oil). I clean the filter about twice a year and that seems to be enough. And, as SBG notes, the compressor is on top of a platform which deflects a lot of water and mud. Also, Extreme Air suggests mounting the AC on the frame rails, underneath the vehicle, as one of the possible mounting locations.

 

[cbetts]

I'm not fond of intentionally driving into mud, but it seems sometimes it is unavoidable. As much as I try to avoid mud, I cannot avoid dirt and dust. Over the years, the AC has been exposed to both, with not a single problem. If you look at the picture of the air filter on the air compressor, you will see that it is the same type as used on dirt bikes (in fact it uses the same type of oil). I clean the filter about twice a year and that seems to be enough. And, as SBG notes, the compressor is on top of a platform which deflects a lot of water and mud. Also, Extreme Air suggests mounting the AC on the frame rails, underneath the vehicle, as one of the possible mounting locations.

Well, the compressor I bought has the ability to put the intake where ever I choose. Thinking about putting that inside the cabin. If I keep the compressor under the hood, I will put the inlet inside the factory air cleaner box.

 

[Mb30sdl]

Do not install compressor under the hood, heat from running engine will shorten its life. I'll be moving mine on H2 to a different location.

 

[Renagade132]

Great job DaveK, and thank you for the information. I already ordered the higher powered alternator so I can do the dual battery. Unfortunately I do have the air compressors in the back, so I will have to find an alternate location for the second battery.
let me ask you a question, having the switch allows you to turn off the power to the second battery, but what is the benefit of turning it off? Why not just leave them connected together so they are providing the extra juice constantly? I'm sorry if I sound ignorant, I just don't know much at all on this set up, and want to do it right the first time. And is it important to get that hellroaring unit?

 

[Renagade132]

And also how much was the cost of the hellroaring unit that you bought? Which model did you get? Thanks again

 

[rascole]

Can you post some pics of your isolator/combiner? I too am looking for one of these Hellroaring's.

 

[DaveK]

I'm glad you were able to benefit from this information.

1. The question about the switch is a good one. There are three positions, on, automatic and off. The on position keeps the batteries combined all the time, even when the vehicle motor is off. The automatic position combines the batteries only when the voltage rises above a certain level, such as when the vehicle is turned on. In this position the batteries are isolated at all times when the motor is off. In the off position the batteries are isolated regardless of battery voltage or the state of the motor. The only reason I would use the off position for is if I was looking to protect the second battery from any possibility of being discharged. There may be other reasons mentioned in the instructions or on their website, but I would have to do some research. My switch is in the automatic position most of the time. When we are on long term trips and I am using the Ham radios, I will manually combine the batteries for the extra juice that the HF radios demand - but only for short periods of time.

2. Is it important to get the Hellroaring unit? Well, for me, it was. I've used a battery switching unit, such as used for marine applications, which allowed the batteries to be either isolated or combined, and it worked fine. The down side was that the unit was strictly manual and located in the engine compartment. Not convenient. In a general sense, there are two other types of of battery isolators/combiners that you can use - either the solenoid approach (such as with the National Luna product) or the solid state approach (such as with Hellroaring.) I chose Hellroaring based on my research and the many reviews I had seen. All of these approaches are good and will work, but if you have any doubts, you should check them out. I can tell you that in almost 7 years, I have not had a single problem and the H2 has over 175,000 miles on it.

3. Cost was about $170.00 (I think). It was, after all, almost 7 years ago!

4. The pictures that I posted, above, are of the remote control unit, which is located in the cab, and of the actual isolator/combiner, which is located on the engine firewall. I can post more, if you would like.

 

[rascole]

Thanks, I am getting ready to do a dual battery set up in my 3 and 99.99% convinced that the Hellroaring switch is the way to go.