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Metalian Maxi/80 Build Thread

@clivehorridge No cctv covering my garage unfortunately and no power for me to be able to set anything up. We already have a method of securing the trailer on the drive so no additional work there. It's a rented garage so I won't have to repair it myself. I'm just hoping they don't try and hold the deposit back or charge me for the damages. It is only a few weeks to the end of the tenancy as well so I guess it could look a little suspicious from an insurance perspective.

@Gr8Yota The Maxi is insured ... but as a trailer tent. It's through the camping and caravaning club. Covers into Europe for trip length of up to a year. The cost for this is around £360. Reading Chris' reply it does make me wonder if I have it insured completely wrong ... but they did take the manufacturer and make. The Maggi tent and front runner roof rack wouldn't have been covered though.

Is the key different between a trailer tent and a camping trailer the tent sitting on top of a trailer? Surely it must be a pretty fine line?
 
Just the perfect amount of space for these batteries. I will have 8 in series in the gap between the water tanks replacing the puny battery that came with the trailer.

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I'll use some aluminium plate connected with threaded bars to clamp the batteries together and then some angle to clamp the batteries to the floor of the maxi. Something along the lines of this:

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Wow. Roll on the Apocalypse there Grant. Next time we meet, I bring a beer and you can talk me through that lot.

That's where I moved my batteries to. I have the big Yellow Tops and they were right at the front making the nose weight impossible. In the end, I had to make some new water tanks to allow me to move the batteries over the axle. It's a different trailer now and I have more space in the front. But at quite a cost. But then the original tanks were quite poor actually. There looks like there is a lot of room there but once you drop two batteries in, it suddenly looks quite tight.

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With pleasure Chris.

Those tanks look a lot nicer than the factory tanks that have been spot welded and edges sealed by brazing.
 
It came with stainless tanks Grant, but they had a ridiculously over complicated external manifold system which had been badly installed. I fixed all of that. I asked Metalian for newer tanks as they'd mentioned that the stainless ones had been replaced with plastic ones. They very kindly sent me the wrong ones.
So in the end I went to my local kitchen equipment manufacturer and commissioned these to my specific measurements. I then joined them internally with a nice big cross pipe so that they filled quickly and evenly without the old airlock issue.
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I had them made without any holes so I could install them and then cut the ports precisely. However, we had to drill one hole in the end due to the issues caused by pressurisation during the final weld. As the welder tried to close the last bit of the seam, the air rushing out just kept shagging the weld up. I wanted them seamless, but he just couldn't do it that way. I did lose a bit of capacity but not much.


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I haven't taken a close look at the external manifold on the maxi but i'm guessing it's the same setup as what yours had. It does baffle me a little that they have that manifold externally for an off road trailer. It is tucked up behind the axle so it's not likely to be hit ... but it isn't beyond the realm of possibility.

I haven't encountered the air lock issue, did yours have an air filter/outlet on the second "slave" tank?
 
Yes it did Grant, but the speed at which you can pour water into the main tank wasn't matched by the speed at which the water could pass through the tiny cross pipe in the manifold and the speed at which the air could get out the other side. I could brim the main tank then wait 5 mins and the level would drop as the slave tank equalised. Just a pain. All sorted now. Yes the manifold was protected but with the flexing of the floor under the weight of water etc etc the thing leaked. I did fix it, but the design was ridiculously complicated with gaskets and brass collars that you couldn't reach. All gone now.
 
Ahh something to watch out for, thanks for the heads up.

I'm hoping I don't see the same issues but not sure there is much chance of that.

I'm battling the doors leaking rain water in at the minute. It's an issue we've had the whole time but not something i've tried to address seriously as it was always stored under cover. I bent the latch "tongues" in more last night on the problem doors so there is more pressure holding the doors closed, they were a bit loose so hopefully that's all it is.
 
Never had a door leak. Not even towing in torrential rain Grant. Sometimes the doors do benefit from a small adjustment though. I had a couple where the alignment was slightly out but then my trailer has some history!
 
Chris, did you run the earth of the batteries to the trailer body and then earth everything from that? I'm torn about doing it that way or running a separate earth for everything.

To complicate things a little the output of the lithium batteries is 24v (closer to 27v when charged) so I have a mix of 24v and 12v devices. The 24v devices (fridge, inverter) will run direct to the batteries and the 12v devices will run through a step down 24v to 12v converter (https://www.amazon.co.uk/dp/B01KQWWVTY/ref=pe_3187911_185740111_TE_item)
 
I continued the setup of the battery bank over the weekend. On the initial charge each cell needs to be charged to at least 3.65 volts. I was experiencing quite a bit of voltage loss through the cheap cables and connectors that came with the charger so I compensated the charger set voltage by the amount being lost through the connections. This wasn't very scientific as the amount varies with the amount of current/voltage so it was a finger in the air moment and I arrived at .06 of a volt. It was still charging as the battery reached 3.65 volts at the cells terminals but had dropped to just a few amps, the charger would have stopped very soon after but I went for the manual intervention mode so the cells all have the exact same voltage to start off with. Each cell came only half charged so it taking around 2.5 hours to charge with my little charger.


Thanks to the tip that @StarCruiser has said a few times about testing the voltage between different points to identify a bad joint.

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I also started planning out some wiring in the trailer, built a little box the 8 bank switch holder. Not mounted or wired yet so just sitting in place.

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It should sit flush with the stainless once screwed in.
 
Smart panel, I'd been looking at similar 'marine' units to make a tidy install.
 
No Grant I did not. I wish I had the electrical brain of Mr Rich when it comes to this magic but I don't. So I play on the safe side. All of my trailer connections are made to the battery posts. I have worked to eliminate any earthing to the shell. Why? Well I have a mix in there of 240 v stuff and 12v stuff and I was keen that they didn't have any opportunity to mix. I've run them as two entirely separate systems with make/break/make change over controls too. I did look into having a big spike to knock into the ground with an earth strap that went solely to the trailer body / chassis. I haven't done that yet, but might if I read something conclusive. I read stuff about metal hulled boats and people stepping on and off and getting zapped because they formed an earth bridge. In my 240v set up, the three wires in the mains come into the trailer and terminate in the internal 3 pin plugs. I have a small checker plug device that I test the mains with before using anything. When I run the inverter, the plug does say that there isn't the same earth but from reading up, I think that's more to do with it being square wave not pure sine. All appliances are double insulated too.

You might say well if you're not a qualified electrician don't do this stuff. Sure, but I have been careful as I said to wire everything up in the described manner keeping everything apart. Yes, a cable could fray and touch the body, so all cables are in cable trays or through grommets etc. Still think a spike with a lead might be a good idea when running any 240v. What I don't know though, is having a spike a BAD idea.
 
Grant, Chris, you should use the body as the negative return where possible on the DC side. Why? It is the biggest conductor and enables you to omit fuses in the negative and only fuse the positive. If you’ve fused both positive and negative, ignore the above. Why would both need to be fused? Well, take the scenario that your negatives that all run back to the battery terminal are all of differing sizes and the smallest somehow becomes trapped against the body of the vehicle/trailer and makes a connection. Will you know about it? The light on the end of it still works and no fuses have blown so no, you won’t. Further down the track your cutlery drawer collapses and traps the largest cable connected to the + of the battery through a 60A fuse. A short circuit is now made from this cable, through the body to the tiny lighting cable and then through that to the - battery terminal. The large cable and fuse see a load but the resistance keeps the load below 60A but applies close to 60A to the lighting wire, rated at 10A max which begins to get hot along its entire length, first compromising then fully melting the insulation and potentially setting fire to anything flammable it touches but no fuse blows. If the body of the vehicle/trailer is at least connected with a cable equal to the heaviest cable from the + side, this scenario won’t happen as the 60A fuse will immediately blow. At this point there is gain to be had by using the metalwork now solidly connected to the - terminal as the return as it is very low resistance and will improve conductivity by decreasing the overall resistance of the circuit.

On the 230v side, the frame must be connected to earth to satisfy electrical regulations (BS 7671 and BS 7909 temporary installations). Reasons are similar to the above and have no problem being mixed as they should not make a circuit through one another, mainly because the body is connected to - and to earth.

As a stand alone unit, the trailer for example using an inverter is classed as a generator. If it also has a mains ‘shore power’ connection then all earth points must be connected to chassis. An earth stake or mat would be beneficial if not essential. Why? In the instance without such stake or mat, your good lady is using the hairdryer and drops it in the puddle created by the outdoor shower. While standing on the wet ground and touching the trailer she completes the circuit back to the earthed trailer and will receive a shock.

You are of course using an RCD which will trip. But will it? Many generators, particularly small ones, only Earth the earth pin to the frame of the generator (giving two phases and an isolated ‘frame’ connection) and not to one side of the winding thus turning that phase into a neutral to go with the remaining phase and now an earth. Without the connection, the RCD will not trip as no fault circuit is made to bypass it (which is how it works).

The only way to avoid connecting the frame either to negative or to ground is to ensure under all conditions that the frame cannot possibly come into contact with any part of the circuit. And that is very difficult if not impossible on a metal structure such as a trailer or vehicle, subject to serious vibration. Grommets alone will often not be enough. I’ve seen them wear through with movement.

This would be along the lines of double insulation and along with regular inspection could be achieved but would rely on testing and inspection to ensure the fault connection was not made. Not recommended except under close supervision.

Chris, the only requirement is that the installer be ‘competent’.
 
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And of course Rich you have given me advice on this over the years whilst I have been building it.

That being said, I can't help thinking that theoretically speaking, your answer - whilst correct I am sure, is somewhat of an overstatement in relation to my actual build. It's a small trailer with some led lights in it, a fridge and the equivalent of an extension lead that I can plug into the camp site mains. It's not a Saturn V rocket at the end of the day. The cable runs are so short they were made from off cuts. I should point out that the cab;es don't actually go to the battery. They go to a distribution block and a fuse board etc. Electrically they connect directly to the battery, but physically they are all circuits with fuses and breakers etc Like a car I guess but not using the body. I have a battery monitoring system in there too which behaves very oddly in relation to where I connect the earths. There's this shunt do-dah which likes to be connected to the shell, but if I connect anything else to the shell it goes nuts on the display. It's beyond me. Come and have a look around next time. I ripped it all out and did it again last year.
 
It’s not a case if how big or small the installation is Chris. You can get shock from short wires or fire from a short circuited 9 volt pp3 battery so it applies from that to the Saturn five rocket. Electricity doesn’t care. The other thing is that even to electricians, some things seem to be overkill. It all boils down to how much is known on the reasoning behind each regulation. Some are more obvious than others and they don’t all need to be used if the perceived risk is assessed and deemed low enough as to be effectively not present. I’m pretty confident that your installations are far better than many electricians would do and you probably inspect regularly so your risk is probably so minimal as to be negligible.
 
That's my view Rich. I know the length of the runs has no bearing on shock, but it does have a bearing on wear and rubbing. The cables aren't running under, over, through and round stuff. They're more likely to be nibbled by mice! Incidentally, I'm not sure how the standards apply to this in any case. Forgetting good practice; as a private citizen on a non commercial basis with no offer for sale etc, there are very few laws that apply to individuals in the UK. A house is different of course but you you wire your trailer for personal use is largely your own affair, I'd have thought. The point here is that it's very hard to communicate technical requirements to the public. And therefore largely governments don't try!

Not arguing, just making the point in general. Firearms are an example. I can put my rifle in the lathe, screw cut it and fit a moderator. No problem. But if I come to sell it, it must have a proof certificate or it's technically illegal. The sale can be regulated, but me in my workshop - I can't.
 
It’s true, there are no laws in the situation you describe. The regulations are there as the pinnacle of safety for you and those around you and here on this thread for the benefit of those less conversant with safety issues than you or I. Your rifle doesn’t get towed around to various locations in all weathers with all manner of people from family to public able to touch it while it’s in a position to be used, your vehicle and trailer do. Various show grounds for instance have rules about the standard of temporary electrics erected upon them. Electrical regulations now even apply to showmen’s equipment accessible to the public.

There is a need for safety in the public domain, which could reasonably be required to be demonstrated with test certificates for example, but if you want to fry or burn yourself you are quite legally allowed to do so, for now anyway. If the items are insured, it is increasingly the case that insurance companies are requiring test certificates to continue insurance. This is coming into industrial sites and in my opinion it is only a matter of time before it filters through to smaller items.
 
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