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Author Topic: Have gone full Tom Hanks in Castaway! Help!  (Read 4275 times)

bouve

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Have gone full Tom Hanks in Castaway! Help!
« on: February 21, 2017, 07:16:07 PM »
Hey guys,

I'm just new to the forum and to Camper Converting. My lady van is called Betsy, she's a 2002 2.8 Iveco, medium wheelbase and she was a total steal, meant to be. I'm converting her for the full- time traveling life.

I've stripped her out as she had a lot of mould and mice and wasps (some of my favourite things) and she's now ready for insulation. But before I can do this I have to re- seal the windows, cut in some extractor fan holes and fit a roof rack to install Solar panels if indeed I do go down that route.

She already came fitted with a Zig CF8 unit, and trying to figure out the other things that I need to complete the electrical system has been a bit difficult for a complete beginner. I say a bit, I mean I've been tearing my hair out. Never the less I have deducted more or less what wiring has been used for the Zig unit to encompass the 12v appliances that came with the van, depicted in the diagrams below: Fig. 1 and Fig 2.




(That still doesn't mean that I know what it all means, for example if I have a split charge relay to charge a leisure battery via the engine alternator and how I would wire anything else running on 12v directly to the system.) I am unsure of how far the previous owners got with the conversion attempt they made so I'm unsure of whether the circuit is complete or not. I would love to be able to add a 12v extractor fan to that wiring system, or perhaps use the bathroom light wiring for a light come extractor fan instead.

My second stage of getting the electrics sorted is leisure batteries, inverters and charging sources which is where I've sort of lost the will to live in that the batteries I will need are of ridiculous spec, given that I don't use much electricity as a person. (Or so I think, I might be wrong)

Below (Fig 3.) I have calculated all figures I believe to be necessary to figure out what battery (ies) and inverter I need, because there aint no party like a spreadsheet party. I have presented the calculations that I assume to be correct and simply need a little help deciphering whether I am on the right track or whether I'm totally way- off. From there it's about deciding which equipment will best help me achieve the power supply that I need.

In Fig. 3 I have looked at all the essential Appliances that I will need to power when living off- the grid which are listed along with their labelled wattage. I believe the labelled wattage to be the highest operating wattage including the initial starting surge, if someone can please confirm if that is correct?



I have also looked at the necessary Amps and therefore Amp hours if using a 12v set-up and a 24 volt set-up, but would I be correct in saying that these figures are to determine how many batteries would need to be connected in parallel to achieve necessary amp- hours to run the appliances, and not in series?

Looking at the possible potential set ups I could go for;
The minimum watts of 865w (142 AH), taking into account a 50% battery depth of discharge to give 248 Amp Hours, using for a minimum of 1 day off- grid without back- up days would require 2x 12v batteries of 130AH each linked in parallel to give double AH.

If I look at the maximum items I will be using at any one time, let's say 720W based on my pattern of usage of the Appliances mentioned, an inverter running at 90% efficiency has already been factored in here and could be say 800w (to 240v) to cover the 720W, plus a bit of extra wiggle room for surges, although I believe surges are already factored into the wattage given in specs for Appliances.

Saying that a 100w solar panel, in bright sunshine, provides a charging capacity of 4 Amps and will therefore take (284/4) 71 hours of full sunshine to charge from 1-100% and therefore 36 hours of full sunshine from 50-100%, halved again when looking at 2 batteries, would be 18 hours provided that the full sun would charge through the panel at 100% efficiency. So for every 142 amp hours used in one day (24 hours) that discharges the battery to 50% (approximately), it will take 18 hours to fully re-charge with a solar panel of 100w, bearing in mind that this can charge off- grid also. I am unsure of what a constant trickle charge every day will do if I were to use a lesser wattage solar panel, as I presume constant top up is good for the battery but also the battery will need full re-charging at least once a month to compensate for 0.5AH per day self- discharge. Is it then fair to say that the battery discharge through my daily usage will increase at a rate faster than the solar panel can charge it, leaving an overall deficit over time which may be bad for the battery?

With a multi- stage leisure battery charger connected to 240v mains electricity when on- site, at a constant current of 5A (average for battery chargers), it would take one 12v battery (284/5) 57 hours from 0-100%, 29 hours from 50-100%, or 2 x 12v batteries 14 hours give or take to charge from 50-100%.

Therefore if I have 2 x 12v batteries of 130AH each linked in parallel, with one days off- grid usage discharging the batteries to 50%, I would then need to take 14 hours on- site charging to restore the battery to close to 100% using a battery charger, or spend 18 hours in full- sun without using the batteries at all to ensure their recovery through solar panel charging, which would be possible only by using appliances connected directly to the 240v mains on- site. I could also use a 10A battery charger to half the rate of charging on grid to 7 hours which seems more feasible. This is sad either way as it means that I cannot be off- grid for longer than one day, and as well as 2 leisure batteries would need a larger solar panel bank to compensate for the slowness of charging in full sunshine, or more than 2 leisure batteries, both of which are costly options. Add on top of this the cost of a charge controller or battery charger and this is racking up quite an invoice.

After all of that, I have some further questions;
Can I also ask how I would go about determining the necessary size of batteries if the spec given with the battery I do choose turns out to be generous and I'm left short?

Can I also charge the batteries by plugging the electric on- site hook up 2 pin male plug to an electric car charging bank, and running a battery charger from a 240v socket in the van to the batteries?

I haven't taken into account here battery efficiency in lower temperatures as I will probably look into this once i find specific batteries that I want to buy.

I am unsure if I have calculated all of the above correctly and would appreciate any guidance that can be given on this.

My other option here is to go for a generator inverter, which is not as clean a source of energy, but can provide many more watts for a decent price compared to that of a solar set- up. It isn't a renewable source but it would allow me to spend as long as I want off- grid, simply by carrying enough fuel to power it.

Given the minimum wattage (the minimum amount of off- grid appliances I would be using in one day) of 865W, with a generator efficiency of 25% (x 1.25), the maximum wattage of a generator that I would need would be 1081.25w. Therefore a generator of 3000w would last almost 3 days before needing to be supplied with fuel and I wouldn't need to go to the expense of buying solar panels and charge regulators, batteries, inverters or battery chargers. I also wouldn't have to wait to find a camp-site or for a sunny day and hope to get enough charge, so a generator would be my only truly off- grid option within a reasonable price.

Is it fair to say that the option of a generator inverter would be much more efficient for my needs or given my needs, are solar panels worth pursuing?

Well, thanks for following this thread guys, I hope it's not been too much of a bore, I've been facing these calculations for about 2 weeks so needed to out- reach to others to see if I've got this all wrong by becoming Tom Hanks when he loses Wilson.

Lots of Camper love, Kat

bouve

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Re: Have gone full Tom Hanks in Castaway! Help!
« Reply #1 on: February 21, 2017, 07:19:39 PM »
fig.1

bouve

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Re: Have gone full Tom Hanks in Castaway! Help!
« Reply #2 on: February 21, 2017, 07:21:06 PM »
fig. 3

bouve

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Re: Have gone full Tom Hanks in Castaway! Help!
« Reply #3 on: February 21, 2017, 07:23:36 PM »
Aaand the images are tiny because I can't upload images bigger than 128KB. Yah.

kryten

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Re: Have gone full Tom Hanks in Castaway! Help!
« Reply #4 on: February 21, 2017, 08:50:03 PM »
Hello and welcome Kat. It looks like your going for a more luxurious conversion, at least with the electrics. To answer your question(s), if you find you haven't installed enough batteries then you can always add them later, just plan this into your build with maybe a storage box next to your battery bank which you can expand into. You can plug into 240v power if your controller allows this. I would suggest buying Mike's book to go along with extensive internet reading a youtube watching. Everything your trying to do has already been done so you should be able to find instructions online.

All the best with your build.

Camper_Dan

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Re: Have gone full Tom Hanks in Castaway! Help!
« Reply #5 on: February 23, 2017, 05:20:11 AM »
Anything regarding heating, cooking, hot water, or refrigeration, are best accomplished via a fueled means rather than electrical.  If choosing electrical, then shore power or a generator will be your best bet.

Only a fool has solar without a backup plan, and the backup plan is usually more reliable and cheaper than the solar.  I charge my house battery while driving, and have a backup generator for when I need it, or want shore type power.  Ditched the solar, and will never go back.

I cringe every time I see somebody contemplating putting holes in their roofs.  Sooner or later, they always leak, and roof vents receive a lot of damage from low hanging branches and stuff too.  Roof vents with fans are very expensive, and not as effective as an under $20 12v fan placed in a window, and done right the windows can be left open during the rain as well.

Moisture is  one of the biggest problems in camper vans.  Moisture and insulation really don't play well together unless the entire system is designed to wick all moisture from the skin of the van to the interior where it can then be evaporated out.  The evaporation process requires both heat and ventilation.  Without very careful design, you will wind up back in the same boat as what you just tore out. 

Insulation in vehicles is largely misunderstood.  It won't hold the temperatures either all day or all night, and even with the best insulation job imaginable, you will not get more than a couple of hours difference between that and no insulation at all.  When combined with proper ventilation, the effects usually don't justify the cost or the potential problems arising from it.  The interior scheme of passenger vans is about as good as you can get for year round comfort.  The cost of a little extra heat is negligible compared to the cost and complications of insulation.  (Real world experience: My current uninsulated window van costs less than half as much to heat as my old very insulated cargo van did.)

Propane is a very wet heating/cooking source.  For each pound of propane burned, it will introduce a pound of moisture into your interior.  In my old cargo van, with two fantastic roof vents with high powered fans, and every window I had open, I could not keep ahead of moisture problems.  When I switched to a window van, I no longer have any roof vents, but I do have better ventilation via the windows.  I also switched to kerosene/diesel for my heating and cooking.  I no longer have any moisture problems.  The kerosene appliances will also run on diesel, although not quite as efficiently, between the two they are readily available anywhere, and cheap.  A seven gallon jug of kerosene will last me about nine months even with very cold winters and no insulation.  I keep my van toasty warm when I'm inside.

Inverter generators usually use less gas and provide cleaner power than non inverter types.  My $99 no name 3.5kw inverter generator will run for about 8 hours on a gallon of gas.  It is currently 5+ years old.  I mainly use it to charge my house battery if I'm boondocking.  My house battery will last about a week between charges.  I use a shore power battery charger plugged into my generator, and it takes about half and hour to fully charge my house battery.  One gallon of gas will last for about 8 charges.   Since I normally charge my house battery while driving, that gallon of gas will last me a year or more.  I would suggest that you get a 4 cycle one, so you don't have to mix the gas and oil. 

Many boat yards will have used equipment stores.  The standard for many years on boats were kerosene/diesel appliances.  Fridges/freezers are among these appliances, and they are gimballed so you don't need to worry about whether your van is level or not.  Gimballed, non-pressurized, kerosene/diesel appliances are ideal for camper vans.  I do prefer the portable kerosene/diesel cook tops and heaters though, so I can also use them outdoors.

Done right, camper vans and boats have a lot in common.  Everything should be water/moisture proof, and/or easy and quick to dry out to prevent moisture/mold build up.  The failure of fully understanding the importance of these principles, leads to the failure of most camper van builds.
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