Mobi-Arc 200x

My intentions with my CJ-7 are to build a self-sufficient trail vehicle that has the means for repair no matter where I am. For that purpose, I carry a variety of tools with me when I leave the pavement and head for the trail. None of those tools will help me get home if I break a spring perch, motor mount, leaf spring, or my frame. Enter the Mobi-Arc. Like a spare tire, the Mobi-Arc is the tool that will get me home when the inevitable trail breakage happens.

The Mobi-Arc is packed with features. You can get optional “Mode Select” modules that plug into the back of the Mobi-Arc and regulate the output so you can use the welding cables as jumper cables. The Mobi-Arc also comes with a bypass kit. In the unlikely event that the Mobi-Arc control box fails (or should you want to move the control unit to a second vehicle), you simply move a few wires around and you have bypassed the Mobi-Arc and the battery will charge as normal. One of the many goals for the Mobi-Arc was to never leave you stranded and the bypass kit ensures that will never happen. It also has solid-state construction, meaning there are no moving parts to wear out over time. Perhaps the best feature is that it will work with your existing alternator if you chose to go that route. Many of the other mobile welders on the market require you to buy their expensive custom alternator.

It seems lately that the art of customer service is fading at an exponential level; however, the customer service I received from Scott at Mobi-Arc was second to none. He was very willing to explain to me how the system worked and discuss various options such as what alternator would best suit me. It was obvious that he wasn’t just concerned with selling another unit, he genuinely cared that the customer successfully installed his product and had good results while using it. The excellent customer service I received combined with the quality and functionality of the Mobi-Arc make it a product that I am willing to recommend to anyone looking for a mobile welding solution.

Installation:

Use caution when wiring the Mobi-Arc. It is no more difficult than a typical electrical upgrade, but as with any modifications to your vehicle, if you are not comfortable and familiar with the under hood wiring of your vehicle, then you may want to leave the installation to a professional. A mistake at this point could cause serious damage to your engine electrical system the Mobi-Arc unit, or yourself. There are specific wiring diagrams depending on the type of alternator you use or what type of vehicle the system is being installed in, make sure you are referring to the correct one.

The Mobi-Arc unit is designed to work with most stock alternators, and would have worked with my stock Delco, however, I chose to upgrade to a 130 amp alternator. Scott at Mobile Welding & Power, the makers of the Mobi-Arc, suggested I go with a Ford 3G alternator. They have a reputation for being a good alternator and have a voltage regulator on the outside of the case, which is easily accessible. A simple modification is required on the alternator before it can be used in conjunction with the Mobi-Arc. The stock 3G voltage regulator must be removed and the brush holder is replaced with a modified brush holder provided with the Mobi-Arc. A small area on the regulator must also be removed with a grinder or Dremel tool to allow the wires from the new brush holder to pass through. Overall it was simple modification that took very little time.

The next step for me was to create a bracket to hold the 3G alternator on my engine. This turned out to be the most difficult part of the installation, by far, but could have been avoided if I had used my stock alternator. There isn’t a whole lot of room for an alternator under my hood since it fits directly under the York compressor for my onboard air. I tried to keep the stock look and position of the alternator bracket, and after a lot of trial and error and grinding (and some yelling) I finally got everything to fit with a little room left to adjust the belt tension. The bracket I used was originally intended to be my prototype. I was going to use it just to test the fit and then build a nicer looking one using it as a pattern. After the struggle of making it fit, I decided just to go ahead and use it since it will mostly be out of sight anyway.

Next came the time to decide where to mount the Mobi-Arc control box. The Mobi-Arc is surprisingly small, (5.27" x 2.57" x 4.6") so it will fit almost anywhere. Things to take into consideration when mounting the Mobi-Arc are:

•  Distance to alternator

•  Distance to battery

•  Accessibility of front and back of unit

•  Away from major heat sources

•  Not likely to get submerged in a water crossing

•  Security

In a CJ-7, the two best alternatives are probably under the hood on either the driver or passenger fender. The passenger side fender is clearly closer to the battery and alternator, but I chose the other side for a few reasons. First, the passenger side fender is already crowded with the plumbing for my onboard air system and various relays for extra off-road lights. When I add dual batteries, the passenger side will be even more crowded.

The second reason I chose the driver side fender is that the #4 cables for the battery positive, ground and alternator connection come pre-terminated with nicely done crimped and heat-shrunk ends and are in 6 foot lengths. I didn’t want to have the wires coiled up under the hood, nor did I want to cut the cables and compromise the existing professional crimping job, so I choose to mount the control box farther away from the battery and the alternator to take advantage of the pre-made 6 foot #4 cables. This allowed me to run the battery positive and negative cables back up out of the way against the firewall and the alternator connection around in front of the radiator hidden inside the grill. All of the wires on the 10-pin connector used with the Mobi-Arc are also in 6-foot lengths, so no wires need to be extended.

Some of the wires on the 10-pin connector will not be used (depending on vehicle and alternator). You have a couple choices here. You can cut the unused wires off at the connector, or insulate the ends of the wire and leave them intact. I chose the latter. I went this route for two reasons. First, I wanted to get the unit installed and ensure that it worked properly before I started removing or cutting any excess wires. Second, one of the features of the Mobi-Arc welder is that it can be easily removed and installed in a second vehicle. If I ever chose to do that, it may be possible to re-use the 10-pin connector I already have since I left the wires intact. I tucked all of the wires up into a black plastic wire loom to keep them protected and keep the engine compartment clean.

Overall, the wiring of the Mobi-Arc was a straightforward and simple process. There was one slight glitch due to an omission on a wiring diagram that had me stumped for a while. A call to Scott at Mobi-Arc provided a quick solution that had my system up and running in no time. The wiring diagram has since been updated to avoid any future confusion.

Once the Mobi-Arc was installed, I then proceeded to put the welding cables together. I got a really good deal on a pre-cut 65ft section of #4 welding cable at the local Norco store. I cut that in half so I can reach anywhere on or around the Jeep if necessary. Make sure you install the welding cable ends properly, as a good connection will be imperative to getting all the current to your welding rod and grounding clamp. If you also have the battery boost kit for the Mobi-Arc, don’t forget to install the quick disconnect so the rod holder can be interchanged with the battery boost clip.

After testing to ensure the battery was properly charging, I then hooked up the welding cables and struck an arc to make sure the Mobi-Arc switched from charging to welding mode as it is designed to do. It performed exactly as expected.

I then moved on to the final step of the installation, the hand throttle. The hand throttle is necessary so you can set the engine to the desired RPM’s while welding. A hand throttle is just an all around handy thing to have on a Jeep for many other reasons as well. Like the wiring, if you are not familiar or comfortable with doing this sort of modification, it again should be left to a professional. If installed improperly, your throttle could get stuck in the wide-open position or not function at all. Choose a place to install the hand throttle that is convenient, yet not likely to get kicked or bumped while you are driving. I chose to mount mine on my transfer case gear shifter. The clamp on the hand throttle (which is really just a bicycle gear selector) is too large and will fit too loosely on the gear shifter shaft. To remedy this, simply cut a piece of 5/8” heater hose to fit around the shifter under the clamp. I went to the local bike store and bought a few feet of shifter cable sheath and ran it from the hand throttle up through the firewall and close to the throttle lever on the engine. This is where everyone’s install will differ depending on the carb or engine setup you have. You need to secure the cable sheath so it stays stationary while the throttle cable moves the throttle lever.

Once the hand throttle is installed, you are ready to start welding and experimenting with different engine RPM’s to get the desired penetration in your welds. I haven’t needed to weld anything yet, but I did lay down some test beads to test the Mobi-Arc. It worked flawlessly and I was able to lay down a nice bead with good penetration using a 6011 rod.

Once I really get the opportunity to test the Mobi-Arc out in various settings, I’ll add a long-term report.

For more information on the Mobi-Arc welder, visit the Mobi-Arc website: