Solar: Trying to decide charge controller location

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Solar: Trying to decide charge controller location

Postby immped64 » Fri Jul 05, 2019 8:50 pm

I recently took a camping trip and discovered that my 12 volt refrigerator by battery alone could not make the long weekend. To me it was impressive that it made 30 hours, but that was only half of the time I needed the refrigerator to stay cold.

I have been considering the idea of going solar for a long time, but this put me over the edge as I would like to take more long weekend camping trips.

I have ordered a 100 watt solar panel with pretty much all of the needed accessories from Renogy.

I am planning on installing my solar panel to my already in place Thule roof rack, even though I don't know exactly how this will go together. I at least know the basic location it will end up.

What has me more concerned however is the how and where of my charge controller installation. I thought I had a good idea just prior to purchase, but as more facts are presenting themselves it is bringing more doubts.

My main battle is in the determination of whether to install this inside or outside of my camper as each method has it's pro's and cons. My charge controller will not be waterproof. This will be installed on a Little Guy trailer.

Here are my thoughts on each placement.

EXTERNAL: This would have the advantage of not having to drill holes in the trailer itself. The disadvantages I see is that the charge controller is not waterproof and it needs clearance on top and bottom so plopping it into my battery box is out. Also there would need to be a lot of solar wire exposed from the top of the trailer down to the battery.

INTERNAL: The advantages here might be that there would be less wire exposed. The controller could be well ventilated. One big issue I might see is how cramped this might be in the trailer given the limited areas that this would even fit. Then I am concerned about the best approach to take with the wire leading from the controller to the battery. I really like the idea of having a raised and accessible panel for hiding wires but this would take up even more space than doing a normal flat mount.

Below is a picture of inside of the camper. You will see a couple rectangles that I added to show basic location of a raised panel and the charge controller that would be on this. Right now I am not thinking of adding an inverter, but perhaps I might want to provide enough space for it to be added later. I have placed this on the right side of the door as there are swinging cabinet doors that might incur a limited range on the left side. Even though it is superficial the right side placement would also have a little shorter cable run.

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If I placed my controller towards the front tongue I am not certain how I would place it. I have considered either replacing out the existing utility box or adding a box that I could mount stationary to house the controller. There isn't a whole lot of room. Perhaps a superior external solution could be found, but it might take a lot of work or money to do.

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I have a few days before the shipment arrives and am hoping to come up with a good solution before summer slips away.

Perhaps someone might have an idea that could point me in the right direction. In searching the web I am finding scant information on installing a charge controller in a teardrop trailer.
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Re: Solar: Trying to decide charge controller location

Postby Jen123 » Fri Jul 05, 2019 9:03 pm

Slim potato Head on YouTube has his mounted externally in one of the waterproof boxes you can get at harbor freight. That is what I'm going to do for my large trailer so I can use the same solar panel that I use for the little trailer.

On my little trailer mine is mounted in the kitchen hatch. No extra holes. I just pull in the regular power cable and feed through the solar cables one at a time.

I didn't like Renogy charge controller and sent it back. Bought an hqst off Amazon. Way nicer. Has a metal case. A display and works great.

I don't know if my solar is correct, but it works.

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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 9:58 am

Hi Jen:

Before I make my decision I want to keep an open mind about things. My installation thoughts are channeled in one direction because I see flaws with other locations. This gives me great food for thought however.

I initially dropped the idea of installing the controller under the hatch due to the amount of cable required and secondly the challenge of getting the wire to that location. There are several challenges with this idea, but what I like is the thought of having the controller centrally located near my fuse box. If this idea was feasible it would out weigh my other 2 thoughts. Really the only time I would care to look at the controller readout would be when I am experiencing an issue. The best placement should be out of the way but accessible which this would be. So my main challenges would be;
1) Getting a good line down to the controller that would be under the hatch.
2) Keeping out new under the hatch leaks in the process. (I already have a hard to locate leak either in the hinge area or perhaps a hard to see gap on the sides near the hinge)
3) My space for installing the controller would be challenging but not impossible. (As with everywhere on my trailer)
4) I'm not sure I could pull off what you did with sending the wire back to the battery underneath the trailer chassis. A strange idea hit me which I don't know whether it would be even possible. If I could locate another battery in the hatch area it would eliminate a lot of wiring. I don't know if I could add a second battery feed to my fusebox???

Thanks for this idea. If I can counter some of the above concerns it may be the best way of going.

I watched a Youtube where "Slim Potato Head" showed his solar setup. He stored a waterproof box with his controller right where the solar panel was.

This would be fairly efficient as there wouldn't be any traceback with the solar wiring. Unfortunately in my case I don't know whether this would work out. I will be getting a 20amp Renogy Rover Mppt controller. I have looked at the online owners manual and the controller requires 6 inches of air circulation both to the top and bottom. Not only this but it says the box should be installed vertically. I think that an otter box might cut off the air circulation. Before I made my purchase I saw a review for the Renogy controller that the user placed it inside of a little larger Dewalt box and located this on top of the battery.

Another possibility might be to have it reside inside of the utility box. My utility box kind of sucks. I don't know whether it is waterproof because I always drape the end of my large trailer wiring inside the box to keep it out of the elements. I imagine I could cut a hole or 2 in the utility box and somehow seal it to the outside world. If I went this route once again the controller would be out of sight and out of mind. I have entertained thoughts of getting a new more stout (perhaps diamond plated to match the front edge of the camper.) utility box. Perhaps the controller and battery could be stowed away in this. There are angled boxes that might fit up front. I would still have to contend with being waterproof. Lots to consider.

Thank you for your ideas Jen!
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Re: Solar: Trying to decide charge controller location

Postby tony.latham » Sat Jul 06, 2019 10:05 am

I'd kick this decision down the road like an old beer can. Wait until you have the controller in your hand.

Is there a place to nestle it in your galley? How about your tongue box? That's where mine is in our current teardrop.

Image

With my new build, the controller will go on the bulkhead in the galley.

I think the bigger question is running the wires from the panel to the controller. :thinking:

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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 11:32 am

Hi Tony:

The reason I am considering this now is in case I might need to purchase anything to make the setup work. I can understand what you are saying though; if the parts arrive and something doesn't come together as envisioned then I am out some money. As a rule I do prefer holding off on decisions until I am holding all the pieces. I do have the tendency to put things off, but I also am aware that summer is ticking away.

I do know a few things about the controller which do help in the decision making process. I know that the controller needs to be waterproofed. I also know the size of footprint that I will need for the assembly.

You have mentioned the hatch or the tongue area for good placements. The more I have been considering this the more that I am leaning towards the tongue area. This would be a short solar wire run that would not open any holes in my camper.

The wiring in general I have seen numerous Youtubes and diagrams which I am comfortable (at least at this point) in contending with. The concealment of the wiring I am not yet comfortable with. As I plan having the Solar Panel on the roof, I would have a lot of loose wire from the trailer top leading to the box area. This may be contended with by using zip ties but I am thinking that it wouldn't be too aesthetic to the eye. Eterna bond could possibly help with concealment, but I'm not liking that thought for different reasons.

The other issue that I presently have no solution for is the fact that I don't have any waterproof storage for the controller. I have considered buying another utility box since my present box I don't care for anyways. That would still not necessarily get things waterproof. I could buy a somewhat larger box and place it inside the utility box. I don't like this idea but it might be the best short term solution as long as the box was large enough to give some air flow and I could have wiring feeds in and out.

I may ask Renogy's customer service for thoughts on external storage.

Thanks for your input Tony!
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Re: Solar: Trying to decide charge controller location

Postby tony.latham » Sat Jul 06, 2019 12:48 pm

Your tongue box isn't waterproof?

:thinking:

T
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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 2:05 pm

Tony:

I could do a garden hose test to see whether it is, but I would suspect the lid doesn't seal tight. The bolts at the bottom of the box appear to be water tight or pretty close to it.

If this does pass the test the next question I will run into is how I might drill a couple holes into the lower portion of the plastic box and have them water tight around the solar wire. I imagine this can be done.

For now I will try the hose test and go from there. Beyond concealing the solar wire leading from the camper down to the hitch area this would certainly be the simplest and non-invasive way to go.

Thanks for the question.
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Re: Solar: Trying to decide charge controller location

Postby tony.latham » Sat Jul 06, 2019 2:13 pm

I might drill a couple holes into the lower portion of the plastic box and have them water tight around the solar wire.


Use cable glands to keep 'em watertight.

Image

:thinking:

T
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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 3:04 pm

tony.latham wrote:
I might drill a couple holes into the lower portion of the plastic box and have them water tight around the solar wire.


Use cable glands to keep 'em watertight.

Image

:thinking:

T


Awesome! Thank you.


I did not try the water test but in looking at the box and feeling around the lid I really think this would be just fine. I might leave the box replacement for a future project.

I now have a rough idea in how to conceal the solar cable. Through the downwards curvature I am thinking of using Eterna bond to cover and hold the cable. In the last vertical approach I will use PVC pipe and an elbow and small horizontal segment will take the cable to the angled portion leading to the hitch. I am thinking about zip tying it to this until I get to the box of which I will use your suggested cable glands to get into and out of the box.

This may not be perfect but it is simple and I believe practical.

Now I will think out how to install my solar panel. :?

Thanks for your help!
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Re: Solar: Trying to decide charge controller location

Postby edgeau » Sat Jul 06, 2019 4:19 pm

Another factor to consider is that for best charging efficiency you should minimise the length of cable between the controller and battery

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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 6:01 pm

edgeau wrote:Another factor to consider is that for best charging efficiency you should minimise the length of cable between the controller and battery

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Yay! Here is an advantage of the Little Guy. :)

Thankfully I am thinking that the cable run will be fairly small.

This will be a fun experiment.

I haven't really done the science about it but at this point I'm hoping to just be able to power the fridge for an extended weekend. If I'm fortunate enough I'm hoping to be able to keep food cold for a week.
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Re: Solar: Trying to decide charge controller location

Postby featherliteCT1 » Sat Jul 06, 2019 6:17 pm

Cable glands are great … however, you must make sure that the thread length is sufficiently long to pass through the material you are passing the wire through, taking into account the thickness of the clamping nut and rubber O ring. The dimensions of the gland are usually set out in the spec sheet for the gland. For example, a 6mm long thread with an 2mm thick nut and a 1mm thick O ring may only allow you to pass through a 3mm thick wall (about 1/8” thick).
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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sat Jul 06, 2019 7:34 pm

Featherlite:

I will have to cross my fingers on that one. I've already placed my order. In looking at this online it gives a thread length of 5mm but I don't know whether that is available length or thread length including the nut. The specified 5mm would certainly cover if it is available length.

I should have known that this wasn't a one size fits all thing.

Thanks for pointing this out.
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Re: Solar: Trying to decide charge controller location

Postby immped64 » Sun Jul 07, 2019 8:08 pm

I would really like to install the charge controller in the utility box but in getting feedback from the Amazon answers 1 person suggested that the height likely is the limiting factor. The online pdf for the 20amp Renogy rover gives the top to bottom requirement as 6 inches in each direction. That would be 20 inches. My utility box is 12 inches deep.

The other limiting factor is that the online pdf says that this needs to be installed vertically.

I've sent an e-mail out to Renogy to see what they might recommend.
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Re: Solar: Trying to decide charge controller location

Postby tony.latham » Sun Jul 07, 2019 8:31 pm

Overall Dimension: 8.27 x 5.94 x 2.34 in

That's from Renogy's site. Assuming I have the right controller.

T
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