7x14 questions

Converting Cargo Trailers into TTTs

7x14 questions

Postby Wampalampa » Thu Mar 08, 2018 10:54 am

Been a reader since about 2013 for projects off here which can apply to other small spaces (hunting cabins, PU bed "conversion," etc).

Addicted to small spaces and eco-friendly living, and already being a minimalist, I don't need a lot but have a few questions.

TLDR: Buying a 7x14x6H cargo trailer, alum skinned steel frame. The 7x14 instead of a 6x12 is bed sideways & room for a go-kart in middle (fits through door). TV is a 03 ranger, all regular maintenance, single owner. Pre-bought much of the stuff except paneling, insulation, paint.

Questions:
After reading on lithium vs AGM I'll most likely be buying due to weight savings, lack of voltage drop, and higher cycles. Do they off-gas like AGM?

V-nose or flat? I've been towing flat at 60mph MAX, often 45-55 on roads other than interstate. I'm only 27 but want to see everything along the way and don't like interstate semi traffic. I pulled a 6x10 3k lbs loaded at 50 and got about 18mpg, will a v-nose help improve this any?

Would you go with another 6-12" height or just bend your knees while showering? Planning on showering with curtains on a string and in a big pan, don't like the idea of wasted space when I'll be standing in it for 30 minutes a month and can have other uses for the space.

Counter tops, 1/4" quartz or something else? Suggestions? It'll be at the tongue with two 7-gallon water jugs and will fill/empty to adjust tongue weight as needed.

Mini fridge or cooler? Currently have a small 3.3 cu ft Danby that uses 1A/75W, but if eliminating the fridge I'll go from ~2500W a day to just 800 a day max.

I'll be having a professional install my solar panel (200W of panel + 80W portable for camping) so it doesn't blow off the roof. How many AH do I need for 800W a day if I go the cooler route?

Found some LED lights (battery powered). Any reason to go with wired lights vs battery and recharge as needed? I don't mind pushing lights 10 times turning the 5 LED pucks on/off.

DC positive is switched/fused and negative will be grounded yes?

Thanks for all replies, suggestions, etc. Will reply. Waiting on trailer to finish.

-Steve

PS: I have a few sketchup models but do the files get uploaded or just screenshot of them?
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 12:20 pm

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Re: 7x14 questions

Postby Wampalampa » Thu Mar 08, 2018 4:07 pm

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Re: 7x14 questions

Postby troubleScottie » Thu Mar 08, 2018 4:42 pm

Wiring is there to centralize the process -- one switch, multiple lights -- plus add in other DC applicances eg fans, frig, water pump, usb outlets, TV, radio, other lights like exterior lights, work lights, inverters, etc. DC outlets like a cigerette lighter or Anderson connectors distributed around the trailer make connecting items easier.

Generally you are looking at a large battery -- 12VDC golf cart, car lead acid/AGM battery 100+AH or lithium. YMMV. So you have a central rechargable system. When on shore power, you recharge the battery -- no need for 120VAC appliances.

Also, if you are going solar, you need a storage for all the extra power that you are collecting that you are not using at that moment. Then there is the issue of transferring that stored power to the individual devices/batteries.

Finally, there is idea of some safety -- fuses to the various devices. As big as a electrical distibution panel or a simple 6 or 8 or 12 fuse panel.


Obviously you can turn on/off each device and remove/recharge/replace individual batteries on individual devices. Some people do not want the hassle of wiring or maintaining a large battery.
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 5:11 pm

Never heard of LFP gassing as an issue.

You're aware of the 7x the cost plus much fussier charging and other care?

Big learning curve, start a new thread for just that, some controversy there.
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 5:12 pm

IMO gotta be able to fully stand if fulltiming, not just for showers.
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 5:16 pm

Watts a day is not a thing.

Watt-hours yes, but for 12V we usually think in AH per day.

An efficient 12V compressor fridge usually uses 20-50AH/day depending on conditions.

A 200w panel is usually enough for that with enough leftover for lights maybe a fan when it's sunny.
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 5:24 pm

Wampalampa wrote:DC positive is switched/fused and negative will be grounded yes?
yes, but no real ground in a van.

"negative return" to a common buss, tied to the engine block. I don't rely on chassis return except maybe for little/cheap stuff.

Fuses sized for wire protection, very close to bank positive.
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 5:24 pm

Wampalampa wrote:DC positive is switched/fused and negative will be grounded yes?
yes, but no real ground in a van.

"negative return" to a common buss, tied to the engine block. I don't rely on chassis return except maybe for little/cheap stuff.

Fuses sized for wire protection, very close to bank positive.
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Re: 7x14 questions

Postby Andrew Herrick » Thu Mar 08, 2018 8:24 pm

Wampalampa wrote:
Questions:
After reading on lithium vs AGM I'll most likely be buying due to weight savings, lack of voltage drop, and higher cycles. Do they off-gas like AGM?

While I would never want to ignore safety precautions, it would seem that off-gassing of AGM batteries is often overstated? VRLA/SLA AGM batteries have a valve that opens to off-gas only at high pressures due to excessive overcharging, which shouldn't happen if you have any sort of a decent charger. But let's say you didn't. If you follow calculations at this site (http://giantbatteryco.com/GLOSSARY/Calc ... ssion.html), you can roughly estimate that, in a camper your size, with a 20% overcharge, you'd need to exchange the air in the room every 53 hours before reaching the 4% hydrogen limit, or every 13 hours to stay below the 1% safety threshold. A simple wall vent or cracked window should take care of that.

Don't take any of what I said as carte blanche that's best practice to run lead-acid batteries in enclosed spaces. But it's important to have a grasp of what "off-gassing" of an AGM battery actually means.


V-nose or flat? I've been towing flat at 60mph MAX, often 45-55 on roads other than interstate. I'm only 27 but want to see everything along the way and don't like interstate semi traffic. I pulled a 6x10 3k lbs loaded at 50 and got about 18mpg, will a v-nose help improve this any?
Never had a V-nose trailer, but my research has indicated that the increased frontal area of a V-nose offsets a lot of the aerodynamic benefits gained by a rounder nose.

Would you go with another 6-12" height or just bend your knees while showering? Planning on showering with curtains on a string and in a big pan, don't like the idea of wasted space when I'll be standing in it for 30 minutes a month and can have other uses for the space.
Taller trailer means less fuel economy and worse handling. Then again, no one enjoys crouching for more than about 0.2 seconds. T@B puts a seat in their campers so you don't have to crouch while showering. Might consider that option.

Counter tops, 1/4" quartz or something else? Suggestions? It'll be at the tongue with two 7-gallon water jugs and will fill/empty to adjust tongue weight as needed.
Do you have the diamond-tipped tools to work with quartz? Otherwise, consider acrylic solid surface.

Mini fridge or cooler? Currently have a small 3.3 cu ft Danby that uses 1A/75W, but if eliminating the fridge I'll go from ~2500W a day to just 800 a day max.
Depends on how much money you have :)

Your calculations infer that you're basing your numbers on 120-volt AC electricity. If you plan to run your fridge off 12v DC electricity, it'll require at least 6.25 amps (1 AC amp ~ 11 DC amps), and that's not counting any inverter losses and start-up requirements. If you have a 100-amp/hour AGM battery, you can use 50% of its capacity, which means you'll run down your battery in about eight hours of continual use. Unless you plan to usually camp in developed campgrounds, that's probably not long enough. So you'd have to upsize your battery pack.

12-volt fridge/freezers from Arb, Engel, Dometic, and other manufacturers draw a fraction of the power, but they're $$$$.

I assume by cooler you mean a thermoelectric cooler, like a Power Chill? Couple things to note: Those things generate heat, so you don't want to keep them in enclosed spaces. Kinda negates the whole point of a cooler. Secondly, in best conditions, you can only expect temperatures about 30-40 degrees less than ambient, and often closer to 15-20 degrees. They're also slow to respond to temperature changes, so if you put your recently roasted hot dogs in the cooler to save for lunch, you've just heated up for everything else for the next hour or two.


I'll be having a professional install my solar panel (200W of panel + 80W portable for camping) so it doesn't blow off the roof. How many AH do I need for 800W a day if I go the cooler route?

Found some LED lights (battery powered). Any reason to go with wired lights vs battery and recharge as needed? I don't mind pushing lights 10 times turning the 5 LED pucks on/off.

It doesn't take long to wire up some lights. If you ever sell it, you'll be thankful. If you ever want to switch out lights, you'll be faced with trying to run surface-mounted wire, which can get expensive in a hurry. I mean, you already have a battery ... why not use it? :)

DC positive is switched/fused and negative will be grounded yes?

Thanks for all replies, suggestions, etc. Will reply. Waiting on trailer to finish.

-Steve

GOOD LUCK, Steve! Sounds you're off to a great start.

PS: I have a few sketchup models but do the files get uploaded or just screenshot of them?
A few of my builds:

ImageImageImageImage


SEE MORE AT: boondockcampers.com
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Re: 7x14 questions

Postby Wampalampa » Thu Mar 08, 2018 8:25 pm

John61CT wrote:
Wampalampa wrote:DC positive is switched/fused and negative will be grounded yes?
yes, but no real ground in a van.

Skip the ground?
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Re: 7x14 questions

Postby pchast » Thu Mar 08, 2018 10:08 pm

NO. You must complete the circuit... I, and several others, recommend running 2 wires to each device.

The positive, supply voltage properly fused, and the negative, return or ground. Chassis grounds are the most common cause of problems in DC electric after corroded connectors. I feel best practice is to lead all returns, or grounds, to a common buss and then to the negative post of th e battery with a large enough wire.

JMHO :thinking:
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Re: 7x14 questions

Postby John61CT » Thu Mar 08, 2018 10:21 pm

Wampalampa wrote:Skip the ground?
You must provide a solid negative return path in every case.

True ground means a copper rod staked deep into moist soil, or a large body of water, that you can skip 8-)
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