Lister 5/1 Diesel

Drawbar Trailer Design & Build

Designing & Building Our 6-Wheel Drawbar Trailer Page 17


We sent the artwork away for printing of the decals, it was 256mb uncompressed TIFF format, or 7mb JPEG. In the end I think Chris used the JPEG file for the print run. They print the whole thing in one go on a multi-colour solvent inkjet printer, which takes a while, but it comes out in vivid colours and the backing material is quite heavy. Chris then leaves it for 48 hours to de-gas the surface, then they laminate a clear film over the top. Once that has been rolled down, a layer of masking sheet paper is put on top.

Applying this size of decal is not for the faint-hearted! Chris assured us that we could do it as long as we followed his instructions, which we did. The surface of the trailer was cleaned thoroughly, then a solution of washing up liquid and water was applied and spread over the whole area where the decal would sit. Then immediately the decal is applied (having stripped the backing sheet partly off to get started) and after aligning it with the marks we had made, it was smoothed down while we pulled the backing sheet off. The whole decal was then squeegee'd and rollered to get the water out from behind, and then it was left to dry.

First decal applied to the trailer side.

Once we had the first one on with no disasters, we popped round the other side and did the second one, which went much quicker as we were ready for it. Once the main decal had dried out we could remove the masking paper from the front, and then rolled the whole surface down to get any air bubbles out. After a few hours they were pretty solidly stuck down, and we went over them again with the roller before we returned it to Chris that evening.

Second decal applied to the trailer side.

Even close-up, it looks good and there is little pixelisation of the image. definitely something we would do again if we needed to, it was far simpler than we imagined. What you get back is a direct result of the effort you put into cleaning up the image, don't expect to get good results with a 10-minute cleanup, the original transfer we used had printing registration errors as well as the surface marks and damage, so there was a fair bit of extra work involved in correcting most of that.

Next job was to sort out the rear lighting. When we first built the trailer, we ran out of time to get the rear lights mounted and wired properly, so this year we wanted to get it done properly with the lights we had bought for the job. Because the back of the ramp is slatted, we couldn't bolt the lights to it directly, but when we cut some strips of 10mm white foamed plastic up, they became much nicer to fit and looked the part.

Rear lights after fitting to the rear of the ramp.

View from the other side.

We also had a bit of a tangle with the wiring in the back, caused in part by the temporary lash up at the rear ramp, so we re-wired that side of things, hiding the cablng behind the plastic sheets which made it look tidy. The three sets of cables came together in an area down by the rear wheelarch, and where they were out in the open before, this time we fitted a small die-cast box to take the junction strip and wiring.

Junction block with all lighting feeds together. The small 2-way on the right is for the marker LED lights on top.

All tucked away and screwed down.

We bought a small 12V compressor so we could pump up the tyres while away or just outside the house. As the trailer is rather bigger than your average car, we made up an extension cable for it, with a 12V socket on the side of the trailer, fed from the 12V fuseboard inside.

External waterproof 12V accessory socket.

Compressor and extension lead. We could reach all round the trailer and the Discovery.

As with most things like insurance, once you have it, you never seem to use it! It's a nice bit of safety equipment to have though, and we have used Philip's pump enough times to know that it will get used at some time or other. Another job finished! At this point we were just about ready for Nuenen, and we made the trip with no problems, everything worked a treat, just a few niggles. There are always some bits and pieces that need sorting out, but we had no problems and a gorgeous weekend as well. Amazing that in the middle of heavy rain we could have a week of hot, dry weather.

Solar Panels were the next job to look at. Lots of smoke and mirrors information, but we decided to go ahead and see what we could sort out on our own. We already had the offer of a new 80Watt panel via our eldest son, one of his friends had bought it and no longer needed it, so that was one. We bought another from ebay which gave us 160Watts of power in theory. In practice it wasn't so easy, and we started on a long road to sorting out the panels and controller, until we had a working unit that did what we wanted.

First 80W solar panel.

First 80W solar panel. Rear connections

Connections changed to 6mm twin cable.

Ratings for solar panels are under 'nominal' conditions, so while an 80W panel 'should' give 80Watts, it doesn't in a way that its always useful. The panels are unregulated, so their output varies with sunlight intensity and the angle that the light strikes the panel surface. We wanted ours to be flat on the roof and fixed there, so we couldn't tilt them to face the sun, and the only time we would get full power was at midday in the summer, the rest of the year we would have reduced output for most of the time.

The other issue is that panels are made up of a series of cells connected in series. This means that if one cell dies, the rest of the cells aren't going to be able to push any power out, and the same applies if one cell is dirty or the panel is covered with leaves. So having two panels started to look like a good move.

Controlling the output of the panels is another can of worms. The ratings are quoted at the panel's best nominal voltage, but that is not the voltage that you need for charging your batteries, so a controller is needed to regulate the output down to a safe charging voltage for the batteries. We intially made up a straightforward dual linear regulator that took the feed from each panel and then combined the outputs of both regulators before going to the batteries.

That worked reasonably well, but there was an area of operation where the output of the panels was too low to make this type of regulator ineffective. The next try was a switching regulator from ebay. Promised a lot, but there were issues with input/output levels, so that got ditched. Another try was what is known as a PWM controller, this being designed for use with solar panels. That was better, but still not delivering what we needed.

Finally we were recommended a particular controller by one of the guys on the motorhome forum, and we ordered it from Taiwan. It arrived fairly quickly, and certainly performed closer to what we were expecting. The technology used is called MPPT or Maximum Power point Tracking, which basically means that the solar panel is allowed to operate at its most efficient output voltage, while the controller chargers the battery at a lower voltage level.

MPPT type controller, 20A.

Solar Panels mounted on the roof of the trailer.

View from further back.

Once we had the panels in place, we were able to test all of the various controllers and regulators, but the last was the best and we wired that in ready for the two autumn shows, Barleylands and Little Casterton.


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