NPS Camper Build

[LeishaShannon]

Hi All

Long time lurker, avid reader, and now new owner of a 2002 NPS ready to be converted into our ultimate escape vehicle. The truck arrived last night straight out of its previous life as a geo-technical drilling rig, covered in mud and in need of a good clean. Today (my birthday) has been spent exploring , taking note of things we want addressed, and starting the mammoth task of cleaning 10 years of crud out of this beast.

 

[blackduck]

WELCOME
and happy birthday, theres nothing else id rather be doing than washing my truck then sitting back and having a coldie
a cab chassis, youve got a lot of dreaming to do now
and to help you along, think of this one simple sound
KA CHING $$$$$$$$$$$$$
but its all worth it

 

[PKDreamers]

Welcome,
We will all look forward to seeing pics and the process of your build.

 

[LeishaShannon]

A few thoughts on design..


We're wanting to build a Camper capable of:
Poor/rough road travel with the possibility of some sand
1-2 weeks independence (energy, food, water)
-10 to 40c operating temp range
Single fuel source (diesel)
Shipping Container-able for travel OS

Truck:
2002 Isuzu NPS 300
Lighter weight side exit exhaust (done!, 40Kgs saved.)
Diff/transmission breathers / sealing air filter box to extend wading depth to ~1000mm
Insulate cabin for noise (done!, much quieter in there now)
12v 40A step-down transformer for chargers, stereo, etc. (done!)

Subframe:
Simple box subframe sitting on chassis rails to prevent excessive point loading.
Spring mounts (tanker style) to allow chassis flex
150x50 RHS Steel rails
50x50 SHS horizontal supports (600mm spacing)
8 x spring mounts, 2 x rear fixed mounts

Camper:
4.7m x 2.1m x 2.1m
Hardwall camper chosen for security and climate control.
Camper will be craned/jacked/forklifted off the chassis for transport with truck in a 40ft HiCube container.
50mm FRP Polyurethane composite panel exterior
20mm Polypropylene honeycomb composite panel for interior furnishing
Pulley system to raise bed above lounge area during the day

Electrical:
24v has been chosen as the main system voltage due to being the same as the truck. A step-down transformer will provide 12V for devices that require it. A small high efficiency inverter will provide 24/7 power for small appliances, while a less efficient high power inverter will be used for intermittent use devices such as the microwave. LifePO4 batteries have been chosen for weight/space saving - the cost is offset by the high number of charge/discharge cycles compared to AGM.

24v 70A idle (130A Max) alternator upgrade
24v 200Ah LifePO4 Battery pack + BMS
6 x 190W 24v Solar Panels
2 x 45A Tristar MPPT
600W Pure Sine Inverter (On all the time)
3000W Inverter/Charger (Microwave, Induction Cooker, AC, other intermittent use devices)
40A 12v step down transformer

HVAC:
Webasto DualTop Diesel Air/Water heater
2.2kw wallmount reverse cycle AC
Exhaust fans in bathroom and galley

Water:
2 x 86L main tanks
1 x 60L drinking tank
1 x 60L grey water tank


Initial Sketches:



Does anyone have any thoughts or suggestions before we take the next step and get an engineer to draw this up for us?

 

[whatcharterboat]

If you want to go offroad, you might run a risk of damaging the front top corners of the camper body. If you angle the sides, yeah it will reduce the risk but obviously loose intertior space in the overhead lockers but you don't really want much weight up high anyway. Anything you can do to keep the overall height down will help too even if it means creating relief for the wheel arches.

Great layout....maybe ask Skifreak if he has any of those bed lifter mechanisms left.

By the way...you will probably need 12 volt less than you think once you start to source 24 volt gear . Also go for switch mode dc/dc converters as opposed to voltage reducers...the general rule is that if it's got a big heat sink out the back , efficiency will be way down.

What's the plan for lifting the body on when you get it out of the container? ( or into the container for that matter?) ......if you are thinking of a forklift, make provision for it to happen safely when the time comes.

Hey...this is all just an opinion by the way..good luck.

 

[LeishaShannon]

Thanks!

Height is definitely a concern, we're looking at about 3.25m from the ground to the top of the solar panels. I had pondered a sort of aluminium tubular exo-skeletion from the front bar up and over to protect the box / panels, but thats going to further add weight and height.
Angled sides is something I will look into, shouldn't be too much of a drama with the current layout as it will only affect the overhead storage and one side of the bathroom. A little more difficult to build too I guess.
The bed lifters we've looked at would block the window and access to the lounge because we want a north-south facing bed rather than east-west.
I've installed a 20A (40A max) switched mode DC-DC from Jaycar in the cab, its..... ok. I find that once the fan starts it wont go off unless the unit is powered off, regardless of the temperature. As a test I removed the load from the 12v side and left the windows open overnight. Ambient temp dropped to 14c but the bloody fan wouldn't stop. Can you recommend a good DC-DC brand with local (Aussie) support?

 

[1Engine]

I have had no problems with redarc gear.
Have you thought about using a charge equalizer rather than a transformer.
You have a better control of peak loads.
You may need to talk to the redarc guys on how they work with the LiPOs

 

[LeishaShannon]

Panel choices

We have been researching the various insulated composite panel options and compiled the following notes. PVC has been excluded due to high cost, while expanded polystyrene (EPS - esky foam) has been excluded due to horror stories of insulation crumbling into a powdered mess.

This left Poly Urethane (PU) and extruded polystyrene (XPS) :

R-Value per inch:
PU: 1.20 initially, falling to .97 after 5 years.
XPS: .95

The R-value of PU insulation can drop over time as some of the low-conductivity gas escapes and air replaces it in a phenomenon known as thermal drift. Most thermal drift occurs within the first two years after the insulation material is manufactured, after which the R-value remains unchanged unless the foam is damaged.

Dow Chemical warranty the thermal properties of XPS for 50 years.


Weight:

PU: 79kg/m3
XPS: 40kg/m3


Water Ingress:

PU Insulation can absorb water (steam, condensation) over time - increasing the weight and reducing the thermal properties. A refrigerated truck built with PU absorbed 2 tons of water over 5 years due to poor construction techniques.

PU: 2%
XPS: < .5%


Conclusion:

For the same weight we can use 45mm XPS vs 20mm PU and have double the R-value, albeit with smaller interior dimensions. Is there something we've missed? Why aren't more people using XPS for campers?

 

[biggoolies]

I would sure like to see how you plan to design your bed pulley system. I am thinking of doing the same to our living quarters to have a full time bed setup. What are the bed lifter mechanisms you are talking about? Not meaning to highjack your thread in this though. :smiley_drive:

 

[LeishaShannon]

http://www.happijac.com/index.php/products/bed-lifts are the bed lifter mechanisms.
We plan to use a simple 3 point pulley system to lift the bed out of the way during the day. During travel the bed would be in the lowered position to reduce the strain on the system. I'll post some sketches of how we envisage this to operate once we've finalised the body.

 

[LeishaShannon]

Cleaning



We had to chisel the mud out of the cab.



Much better!


We then removed the seats / trim and installed Dynamat



New floor mats complete the interior clean up

 

[Alastair D(Aus)]

Me too

Leisha,
I am currently at the beginning of the same project based on a 2007 NPS. My time has to be shared with other demands and hence progress is slow.

My design started out with roof height as a key criterion and I wanted it to be able to go into a container. My solution was essentially a shoe box with the long sided overlapping lid being raised by linear actuators. This is still on the books as I have all the stuff to do it. We have taken a 4wd overseas before and have now decided that we have probably done all our big o/s trips and in future we will source a vehicle in the destination country as needed. This has resulted in us probably backing off to a rigid wall box along the lines of your design.

I am keen on modern technology but in my build I am using established commonly available components. First it is easier to find replacements when needed and the cost is far lower. I agree it is nice to push the margins and if you have the money then great but make sure you consider back country repairs.

I have used Redarc equipment for many years and whilst it is not leading edge it has proven to be robust and flexible in use. The company also really stands by their products and are very helpful with advice. The replaced an intermittent dual battery solenoid outside the warranty period because it had failed within warranty but I only returned from Central Asia much later. I am using several of their bits of gear in the new build based on my experience.

I would think carefully about using 24v for the house system. Most gear made for the caravan, motorhome and RV world is made for 12v and the 24v versions are typically more expensive. I am using a Redarc BCDC1240 charger which happily takes power from the 24v truck system or solar panels and charges the 12 house system using a 3 stage protocol. This removes a lot of the hassles and if you search around you can get good prices. Given this is a key unit in my system I may carry a spare.

Lighting is easy nowadays in that most LED lights are made to run from up to 32 volts and the cost has dropped greatly. I can't understand why people still use flouro, halogen etc. They must not appreciate the current draw.

Having a totally self contained system is wise. Whilst grey water tanks are not yet mandated they are required for National Parks and on a recent trip to NZ we found that all motorhomes there have to be self contained. My guess is it will happen here soon. I am putting in a shower as the 'chief architectural approving officer' stipulated it as non negotiable !! This means that our water capacities will be up on yours. We have always had multiple tanks in our vehicles so that there is redundancy and I try and make sure all water is drinkable unless desparate. We have a good filter system which will be plumbed so that I can move water between tanks and choose which to use. In the past we have found when travelling in remote areas where the water quality was poor our approach worked well. This includes o/s in regions where the water borne risks were known to be high.

Will finish now and pardon the long winded comments but I have spent a lot of time thinking and researching before starting the build and even now I am changing things as I actually construct things.

Happy to exchange ideas and knowledge if it is of use. Please do not speed ahead and get yours finished quickly as a few of us will be very jealous.

cheers

 

[LeishaShannon]

Exhaust



We decided the old stack had to go, it was too heavy and the rattle of the end cap was getting to us.



The new exhaust saved almost 40Kgs over the old one and is much quieter in the cab.

 

[LeishaShannon]

Subframe rails


It fits!
The 20mm spacers between the chassis and subframe will be replaced with rubber when finished.



The step on the chassis has two distinct angles.
The mounts will be fitted with 2 100mm springs to allow some flex of the chassis.

The rear mounts will be of the pivoting type to allow access to the starter motor, transmission, and underbody tanks by jacking up the front of the camper.

 

[LeishaShannon]

Subframe

Not much has been happening on the truck recently due to work commitments but we did get the subframe finished some time ago:



Spring mounts:



Pin at the rear to allow the subframe to tilt: