Cargo Trailer Camping Converting

[Wrybread]

I'm glad your friend doesn't need to do any of the things I've suggested but that's his choice. If he doesn't mind running his batteries down by unnecessarily doing something as simple as pre chilling his refer and beer. fine. The suggestions I've made are ,as far as I'm concerned, are sound and will insure his batteries don't get unnecessarily abused. There's many ways to approach solarizing an RV and I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.

Me too, which is why I was offering him another panel. I'm not presenting his specs as a model, just to point out that powering a 65 watt load for a few hours a day is simple for a decent solar system. Hell, my system (600 watts of panels) puts out over 90 watts from the first meaningful rays of sun and puts out 450 watts most of the day, so powering that fridge even without batteries all day long is trivial. But interestingly he says he doesn't need the extra panel, and I've camped with him for weeks at a time and his fridge does just fine. And he's had those batteries for at least two years now.

And sure it's best to pre-cool stuff before camping, but obviously that's not always possible, nor is it necessary.

I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.

Me too.

[Wrybread]

And to figure out your wiring, if you don't know it already, you need to learn Ohm's Law: Watts = Volts * Amps (a good way to remember it is "West Virginia"). So if you have 2 300-watt @ 45 volt solar panels mounted in parallel, you have:

600 = 90 * Amps
600 / 90 = 6.6 amps

If those two 300 watt @ 45 volt panels are wired in parallel, you have:

600 = 45 * Amps
600 / 45 = 13.3 amps

Using the chart here:

http://www.cerrowire.com/ampacity-charts

You can see that 12 gauge wire is fine for that. However, if you increase that to 3 300-watt panels, you get:

900 watts = 45 volts * Amps
900 / 45 = 20 Amps

Now you need that 10 gauge wire.

[littleharbor]

I'm glad your friend doesn't need to do any of the things I've suggested but that's his choice. If he doesn't mind running his batteries down by unnecessarily doing something as simple as pre chilling his refer and beer. fine. The suggestions I've made are ,as far as I'm concerned, are sound and will insure his batteries don't get unnecessarily abused. There's many ways to approach solarizing an RV and I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.

[Wrybread]

Seconded on the advice to get the 40 amp charge controller.

That being said 400 watts of solar panels isn't going to get you to 40 amps of charging power. If you are just going for weekend trips and the trailer can catch up during the week you may be alright. If after a couple 3 day weekend trips you find You're working your batteries too hard and not able to recover you will need more panel output. Personally , considering you are just in the building stages, I'd buy a couple inexpensive 60 cell 265 watt panels and a decent MPPT charge controller.

I don't agree with this. It's not like his fridge pulls 40 amps. The OP says it pulls 65 watts (~5 amps), which is easy. My friend and neighbor has this fridge, which pulls the same 65 watts, and he powers it for weeks on end with his two crappy 12-volt panels totaling 240 watts going into two Trojan T105's:

https://www.amazon.com/dp/B0012EGZ9S

He doesn't pre-cool the fridge or anything in it. I've got an extra 300 watt panel, which I offered him, and he says he doesn't need it. And he has lights on literally all the time (he has blue LEDs that permanently shine under his trailer for effect) and plays his stereo with his obnoxioulsy loud subwoofer all the time. (And don't get me wrong, I have nothing against obnoxioulsy loud music, as long as I'm the one playing it...)

[Edited to add: I'm not suggesting that his specs are a model to shoot for, I think he's under powered, but it's an illustration of how easy it is to power an occasional 65 watt load from decent solar]

As far as these panels:

http://www.kijiji.ca/v-electronics/e...utm_source=sms

Those are the specs I use. I have two of them, flat mounted, feeding into a 40 amp, 100 volt charge controller:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I get about 450 watts of power from them when the sun is high on most days.

The problem is that those panels have an open circuit voltage (VOC) of 45 volts, and if you're running two of them in series that means you get 90 volts, which is close to the rated voltage of the charge controller. And some very knowledgable people on this forum have said that I might get a spike in the morning that exceeds the 100 volt rating of the charge controller. That of course begs the question of what exactly will happen: nothing? dead charge controller? or sparks? I'm in Northern California and haven't travelled to the desert yet, where a cold morning might provide that spike.

Anyway, you can avoid the issue by getting the 150 volt version of that charge controller:

https://www.amazon.com/SolarEpic-Cha.../dp/B00YCI48F4

It's not much more $$ anyway. Make sure to get the remote monitor box (it's on that page too), since that controller doesn't have any display.

Or, if you have the $$, get the Morningstar MPPT-45. I'ts more than twice the money when you include the display (at which point it's about triple the price), but it's probably a bit better, and is 150 volts. That said, lots of folks have done side by side comparisons and the output from the Morningstar and Tracer are pretty much identical. And I have nothing but praise for my Tracer, and I have yet to read a single bad review for it from anyone who's using it correctly. But if someone gave me a free trade-up to a Morningstar I'd take it!

And another possibility I should mention:

I use my RV for surfing, which means it has to carry surfboards on the roof. When I carry more than my usual quiver I have to cover part of one of my panels part time. When I do that, I switch over to parallel wiring of my panels, since otherwise covering one of the panels will kill all my power. I've compared the output between parallel and series and I'm getting the exact same power output from the panels. Granted I haven't compared it when the sun is lower, which is one of the traditional times that an MPPT charge controller will extract more power from higher voltage, but I don't get much power when the sun is low anyway. .And of course the panels are still 45 volts, which is still high enough for MPPT to do it's thing. And when they're mounted parallel I can fit 3 of those 300 watt panels without exceeding the specs of my controller. And I get those 300 watt panels for all of $150 if I get "last year's model", or $210 for the latest and greatest. Sure it's an unknown brand, but I compared them to a set of Canadian Solar panels and I was getting the same output per rated watt.

If you do go parallel though, you need to fuse your panels for safety. Put one fuse on each panel:

https://www.amazon.com/dp/B019YP0HQ8..._Y1oezbEV0ZKE0

And I use these joiners:

https://www.amazon.com/gp/product/B019ZM0TZE

And one thing I should mention is that when you're going parallel you need thicker gauge wire, since the amps being carried by your wire is higher. So definitely get the 10 gauge wire, it's not much more expensive anyway:

https://www.amazon.com/Black-Gauge-S...ICM/ref=sr_1_4

[littleharbor]

UrbanElite, I added another paragraph to my previous comment.

[UrbanElite]

For sure, great idea, I was thinking the same to to get the compressor to kick in here and there to see what it would spike at ect... plan is to use it little as possible when camping but for sur Weill have to open it a few times throughout the day. I ordered a tester, so once it get here I'll plug the fridge in, fill it up and do my test for a day or 2

You may want to simulate some real world conditions. If you are starting from a warm fridge when you take your trailer camping do the same with your test. Load it with food and beer. Is your beer going to be warm when you load it? Use the fridge as if you would when camping opening it throughout the day to get drinks, make sandwiches etc. This will get the fridge cycling somewhat like if you were camping. If it just sits unused when you are metering it, it wont cycle anything like it's going to otherwise.

[littleharbor]

You may want to simulate some real world conditions. If you are starting from a warm fridge when you take your trailer camping do the same with your test. Load it with food and beer. Is your beer going to be warm when you load it? Use the fridge as if you would when camping opening it throughout the day to get drinks, make sandwiches etc. This will get the fridge cycling somewhat like if you were camping. If it just sits unused when you are metering it, it wont cycle anything like it's going to otherwise.

If you are going with 4-6 volt batteries that will give you 440 amp hours @12 volts. I would recommend a 40 amp controller as you would really like to be able to get something near that, (40 amps) to properly charge your batteries. That being said 400 watts of solar panels isn't going to get you to 40 amps of charging power. If you are just going for weekend trips and the trailer can catch up during the week you may be alright. If after a couple 3 day weekend trips you find You're working your batteries too hard and not able to recover you will need more panel output. Personally , considering you are just in the building stages, I'd buy a couple inexpensive 60 cell 265 watt panels and a decent MPPT charge controller.

[UrbanElite]

Sounds good, I'll look into picking one of those up and running that fridge for at least a day or two inside my house to see what it actually runs.

what about these? Maybe return the 2 100 watt panels for these 320 watt panels, get 2 of them to have 640 watt give or take they are $225 each

http://www.kijiji.ca/v-electronics/edmonton/solar-panel-sale-320w/1267339081?utm_campaign=socialbuttons&utm_content=app_ios&utm_medium=social&utm_source=sms

how do you figure out what is the right solar charge controller size wise, what is my min of A I want to go with 10,20,30 or 40?

[Wrybread]

I personally have had fantastic luck with 4 of those Trojan T105's and 500 to 600 watts of solar, which is enough solar to keep those batteries healthy. And depending on how much power your fridge pulls in real world use (duty cycles, actual power consumption), I think it'll be plenty, but to confirm, get a gizmo called a Kill-o-watt ($20 at most hardware stores) and measure the actual power consumption over the course of a few days and post it here and folks will chime in.

[UrbanElite]

From my research its it's a pretty low watt and efficient fridge. I'll have to try it and find out!

so panels I'm going to need more power then? Would another 200 watts those same panels do to make 400 watts in panels?

batterys. What if I got 4 maybe could do 6 of those T105s that should be enough juice I'm thinking with the right charge controller.

Gar, I posted a response but it's held for moderation since it has a link. Anyway, says much of what LetitRoll says, except I'm a bit more optimistic for that fridge. I am however completely optimistic for the other fridge I posted, on the off chance the one you have doesn't work out. So one way or another I predict sun made ice cold beers in your future.

[Wrybread]

Gar, I posted a response but it's held for moderation since it has a link. Anyway, says much of what LetitRoll says, except I'm a bit more optimistic for that fridge. I am however completely optimistic for the other fridge I posted, on the off chance the one you have doesn't work out. So one way or another I predict sun made ice cold beers in your future.

[LETitROLL]

You can wire your lights anyway you wish (single switch, separate switch to each, etc.) ,deep cycle 6v batteries are usually better, you just use multiples in series to come up with your system voltage (12v or 24v, etc.). Wiring most panels in series to a MPPT controller is usually best for maximum harvest, but each exact combination of panels and controller can vary a little depending. Going to be tough to run a A/C mini fridge off of 200w system, If you only go on full sun summer days, have a good MPPT controller, never park where the possibility of shading exist, and set your fridge to the warmest setting, it will still be borderline but may work short term. Conservation rules the day with small systems, an efficient DC fridge and/or having the fridge unplugged at times and warmer than ideal inside temps can make it possible to "get by" with a small system, but if the fridge is A/C only and going to run 24/7 as indicated in your opening post, it is probably not going to happen with 200w solar, without buying new batts very often.

[Wrybread]

In broad strokes, you put a fuse on your battery (see my recommendation here).

Your solar panels connect directly to your charge controller (see my wiring recommendations in that thread too). If you get an MPPT charge controller, you'll be wiring your panels in series. If you don't know what that means do a little research and let me know if you still can't figure it out.

Your charge controller connects to that fuse on your battery. You never disconnect it except for maintenance.

For your cabin lights, get a fusebox, which you connect to the fuse on your battery. I've had great experience with these for years (here's their smaller version). Since they have the grounding block attached it makes things a bit simpler. Or of course you can get a separate grounding block and use whatever DC fuse box you want.

And your inverter connects directly to your battery, as close as possible, not more than a couple of feet away. If you don't have one already I'd recommend the Xantrex 600 or 1000 watt, and get the remote on/off switch so you don't need physical access to it. Don't get a crazy powerful inverter (1500+ watts), they can't supply that kind of power anyway and it's a red flag that they claim to.

And remember to vent your batteries to the outside. Super super super important, since they gas when they're charging. Also make sure your inverter has good ventillation and room to breathe, since that fridge is a fairly big load and the inverter will heat up. The Xantrex has a fan and does a good job of keeping itself safe. Over the years I've had a couple of them die, but they die peacefully, as opposed to a flaming blaze of glory... Which is one of the reasons I recommend them so highly.

[UrbanElite]

No this is a mini fridge from igloo, kinda like a bar fridge. I'll try to find a link and add it to my next post.

ok I'll take a look at those, what's the big difference from those being 6v and not 12v, which is a better battery system to go to?

Ok ok I'll take a look. Just camping all over the place really, where ever we go camping with friends and dirt biking.

so what about my lights, can I wire all those to different switches, with a fuse block, but where would that connect to? The load side of a solar charger or would you just hard wire that into the battery's at the end of the day?

how would you recommend me wiring my panels series or parel to start with these 2 panels?

[Wrybread]

A 65 watt fridge should be totally doable. That's the same amount of power as the one I was recommending by the way, so who knows maybe it's even the same one. Got any deets on it? There's someone else on this forum currently looking to do the same thing you are, see the '67 Airstream thread.

And yes, those are the batteries. I've only ever used those, but I know there's knockoffs, I think Walmart has some? Maybe someone else can recommend something?

For the charge controller and my other gear recommendations, see my post here (scroll down a few from this link):

https://www.solarpaneltalk.com/forum...e-advice/page2

And where will you be using your trailer? Is it one area specifically, or all over? I'm asking because of the temperatures.