I initially mounted two group 27 AGM batteries under my sink. That was the heavy side of the trailer, so one side of the trailer rode lower than the other. I could see it in my rear view mirror.
I stopped at a rest stop dump station to dump, and when I bent down to take my hose off, I could see there was something hanging down from the bottom of the trailer. It was a piece of angle. One end had three ground wires attached to it. The other end had gone across the top of the axle and hung up in the brake wires. I took the ground wires off and threw it in the back of the truck. It was a flimsy piece of sheet metal that had been bent to form an angle. I could not see how it could be structural, so I called Jayco and asked if it was structural, or if it was there to have something to attach the wires to. If it was the latter, I would just feed it to the chop saw and tack it to the side of the frame with the MIG. They talked to the engineering department and then I was told "Sir, you need to take hitch that trailer up and take it to a Jayco dealer". Well it was out of warrantee, so that wasn't about to happen.
Here is a picture where you can see the ground wires attached to the angle:
In this picture, you can see where it had been previously welded to the bottom of the i-beam just to the right of where it is now.
The problem was, it was supposed to be below a piece of C channel that was up against the bottom of the floor. So they cut it out, moved it, and welded it back in. But when they cut it out, it was too short to weld along both legs of the "L", so they only welded it where it rested on the bottom of the i-beam. Well, the flexing of the frame broke the welds via metal fatigue.
As you can see in the previous picture, I managed to weld it along both legs, despite the fact that I could not see what I was welding. I got to looking at the rest of the frame and a found a cracked weld on a big piece of C channel they had made out of sheet metal. They had stitch welded it, and the bottom weld was cracked. In the following picture, you can see where I welded the full length of the end of the C channel.
Toward the back of the trailer, I found another arrangement with small sheet metal C channel over sheet metal angle. So I criss cross braced both of these arrangements to make a truss. This next picture is the one toward the back of the trailer.
I got to thinking about all of this and looking at these cross members. They were each about 5 feet apart from each other. The big C channel was just aft of the center spring hanger. With frame twisting in turns, there was just not enough structure there. So I decided I would add four pieces of 2 x 2 by one eighth angle between the i-beams. In fact it would be two trusses. And then the idea hit me. The one toward the front would be a full truss. The second one would not be a full truss, but would be behind the front one by about 15 inches and trussed along the bottom to the one in front. I could basically frame a long box that could be accessed from the rear. This required a little angle in the corners too. Then I could attach some insulated panels to it, put I plywood floor in it, and move the batteries there. The heat duct ran right overhead, so I could tap into it to heat the compartment. I would just have to screw and insulated cover over it after the batteries were installed. Due to the size of the batteries, the lower pieces of angle had to drop down a bit. In the next picture, you will see the trussed piece that had fallen out in the foreground. In the background, you see the front of the box. Unfortunately, because of the insulated panel, you can't see the steel framing truss structure.
The square steel tube you see going away from you is part of the slidout mechanism. You can see where the angle drops down from the bottom of the i-beam at an angle. Note: the polyflex on the bottom of the floor is flammable. I had to use pieces of cork as heat shields between the top angles and the polyflex when I welded them to the i-beam. Even then, one piece of cork started burning. But I was prepared with a squirt bottle that had water in it. I also had a big 2ABC fire extinguisher sitting nearby.
The insulating panels are framed with 1x2s. The center is filled with 1.5 inch think Owens Corning pink extruded polystyrene insulation. This is then covered in fiberglass. After installation, the cracks are sealed up with Great Stuff expanding foam. Then everything is painted black. In the next picture, you can see one of these panels that I use as a cover on the rear. It is screwed to the other pieces with a bunch of screws.
When I first did this. I cut about a 1" square hole up into the heat duct. I used foil HVAC tape to line the hole. It essentially formed a minurature duct. But as it turned out, that was too much heat, as it is about 3 feet from the furnace. The batteries went up to 138 degrees and killed the life of my batteries. In the next picture, you see where I put some tape over the hole and then punched a very small hole in the tape. That is all that is needed to keep the batteries between 60 and 70 degrees when the furnace is keeping the inside of the trailer at 70 degrees.
For reference, the black tape is 2" wide duct tape.
The cold air return out of this compartment is the hole in the floor where the cables come in. They are very large cables because I have a Xantrex ProSine 2.0 which is a 2000 Watt invertere and 100 amp three stage programmable charger. Here is a picture of the cables where they come into the compartment.
There is actually a lot to see in that picture. You can see the back side of the end panel where I had to foam the crack between two pieces of insulation I pieced together. You can see the vertical pieces of angle in the corner of the box. If you look at the very top of the picture where the cables come down there is a little spot of pink. That is the fiberglass insulation between the polyflex and the bottom of the floor where I cut the hole. The thing that lookes like a gray telephone cable is the wire to the battery temperature sensor. You can also see up there where I had to fill a gap between the top of the insulated panels and the bottom of the polyflex with some Great Stuff expanding foam. Behind the cables to your left is a piece of plywood. This keeps the batteries from flying out through the front insulated panel if I have to hit the brakes in an emergency stop. There are actually battery trays screwed to this piece of plywood that the batteries are strapped into. You can see the batteries in the next picture.
Again there are several things to see in that picture. The obvious one is the yellow battery temperature sensor on the negative terminal. That is the battery right below the heat source. You always put the sensor on the warmest battery. You will see three horizontal black stripes below the batteries. The bottom two are foam gaskets for the cover. The top one is the angle that goes from i-beam to i-beam. You will note there is a little divet in it just below the left battery. That makes the edge of the angle even with the plywood floor in the compartment. That is to aid in getting the batteries in. I have to put them on a mechanics creeper and roll them under one axle. Then I transfer them, one at a time onto a transmission jack sitting between the front and rear axle. Then I crank them up and slide them in. You will note in the picture that you can barely see a scrap of plywood that is screwed to the floor behind the left battery. There are several of these in there. They help keep the batteries from sliding around because the straps on the trays that are fastened to the forward wall are not heavy duty enough to do the job.
Here is one more picture of the mongo fuse. It is a 300 amp class T fuse. Yes, it would be a pain to change it, but I don't carry a spare. Too expensive. If I blow the fuse, I still have a group 22 battery in the original battery compartment I can switch over to. It is recharged by the stock converter.
It was a lot of work. I actually did a lot of the welding one afternoon that I was off sick. I had been suffering from an e. coli infection the night before and into the morning. Dropped a big slag of molten metal on my pant leg. Burned right through. Up until about a year ago, I had a nasty scar there. But I got it done, and now the trailer is level side to side.
And for those that haven't figured it out, those are AGM batteries. They were originally developed for U.S. fighter planes and can be used in any position. Moderator edit to re-size pictures to forum limit of 640x480px maximum.
* This post was
edited 02/14/11 10:17am by an administrator/moderator *
That was quite a project. Was Jayco relying on the thin angle member as a lateral frame brace?
I have seen that thin gage (~1/16. 14 gage approx) used as stringers but not in the axle area. More so from the axle area up the frame header or behind the axle area and to the bumper.
In the axle area I've seen a 2 x 2 structural tube going left to right tie the I beam main frame rails together to help the frame from twisting. Generally the front and rear spring hanger area. But all TT’s or 5er’s are not created the same.
Your AGM batteries, does that style battery not need ventilation? I have not ventured down the AGM road yet, still in the lead acid arena.
Nice cable job. Did you have a crimper or buy the cables made up?
Thanks for sharing. Always good to see others mod’s and fixes. Tuck them away for some day of when to use them…
John & Cindy
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver
2004 Sunline Solaris T310SR
(I wish we were camping!)
Good job. I currently only have one battery, which is what it came with. It's under the oven, in a tin box accessible from the outside. It's slightly behind the axles.
The layout and wiring are pretty poor by today's standards. I was hoping to put two AGMs in that area under the oven. I had wondered if that would overdo the weight on that side. I figured, what's another 65 pounds? Maybe I figured wrong.
I sure don't want to have to put them under the trailer, but that is the next best space. I don't mind getting under there if they need attention, but the fab job you did is would be lot of work for me. I'd have to re-learn how to weld.
The frame is actually made by Leland Engineering, which has been bought out by Dexter Chassis. Those cross members are about 1/16th. I don't know what they were thinking, unless it was that the 8" high i-beams would not twist. Must be the magic trailer frame ferries.
AGM batteries are what are used in UPS. As long as they are not charged above a certain voltage, they will not gas and do not need ventilation. This is backed up by the OSHA regulations on having them in a data center. That said, if you use AGMs you really need a charger that has an AGM setting and a temperature sensor to take full advantage of the technology. With a remote display and temperature sensor, this runs from $350 to $500 in the 40 to 60 amp range. That is actually a better investment than the batteries, as it will make a set of golf cart batteries perform almost as well as the AGMs. The AGMs in my size (Dekka group 27, 92 AH) are running me $180 each with trade in at a local battery warehouse.
The cables were pre-made by a solar power outfit in California. They are very expensive. Were it not for the inverter, I would not need that heavy of a cable or fuse, and could have made my own cables much cheaper (I have a crimper for aircraft cables that we have used in making cables for a friends trailers).
Knowing how to weld really opens up the realm of posibilities when it comes to maintaining and modifying trailers. I have welded on 4 trailers so far, two of them my own. This Jayco I have now was only a week old when I started welding on it. My neighbor comes out and says "David, you just got that thing and your already welding on it!" I told her it isn't really mine until I have welded something on it!