Documenting my solar install

[Seraphim]

Next, I drill a hole in the floor, beneath where the controller will be mounted, to run the battery cables. I connect the negative wire to the battery, run it through the hole, and connect to the controller, where it indicates the negative battery wire is connected. I then connect the half of the positive battery with the metal ring, to the positive battery post. I run the bare end of the other half up through the hole and connect it to the controller. Ther is no power yet - no circuit - because I haven't added the fuse. When I add the fuse, the controller will have power.



Note in the photo, I also taped the two postive halves together, so the spade connectors are next to each. I haven't added the fuse yet, so there's no power to the controller.

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Before I add the fuse to the battery cable, I want to prep the panel cables.

First, I cut the wires to the proper length, so they'd reach the controller, but I cut them a bit longer so there was a little slack. Before I cut, I made sure I taped the positive wire again, up past the cut, so I could identify it. Of course, this is where I forgot to go back to the roof, and pull a little extra back up the vent before I cut, so the wires from the panel's ended up a bit shorter than I would have liked. No disaster, and I could add some length to the cable if I wished. Maybe later.

I also cut a length - about a foot - off the end of the postive wire, so I could install a fuse there also. I added the fuse connectors in the same way I did for the battery cable. This time, however, I went ahead and installed the fuse. I cut a hole in the access panel, and ran the panel wires through the hole, leaving the fuse concealed behind the panel. The fuse won't do anything - there'll be current in that wire - until I take last step and make the final connection on the roof.

Putting wires through the panel:

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With the panel fuse in place:

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Put the panel back in place with the panel wires protruding. Reminder; there is still no power to system because the solar panels need to connected on the roof, and the battery cable doesn't have its fuse in place, either. So I went ahead and connected the panel wires to the controller, instead of waiting until the controller was under power from the battery.

Again, according to the manual, the battery has to be connected befor connecting the panel's.

So in goes the fuse, and tah-dah - battery power to the controller...

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Correction to the post two above.

With the access panel in place:

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The controllers panel lit up, so I went back up on the roof and connected first the negative cable, the postive.

Everything looks good.

Of course, it's dark, now, so I'll check it out in the morning. But, the systems installed, and there no fires or sparks. Tomorrow will tell...

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Oh, I did mount the controller:

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And with the steps in place...

 

[wagoneer]

Could someone explain to me the logic in using #4 wire from the controller to the batteries It's not like your moving amps around, your just charging volts?? Am I missing something. I can see using #4 from the batteries to whatever.

 

[Spaceman Spiff]

Could someone explain to me the logic in using #4 wire from the controller to the batteries It's not like your moving amps around, your just charging volts?? Am I missing something. I can see using #4 from the batteries to whatever.

But I am moving amps around. I am stuffing amps from my solar panel into my battery for later use. I want to harvest the maximum amps from my solar panels into my batteries. To get the maximum amps into my battery, I need the highest voltage the batteries can safely handle to pack as many amps into the batteries as I can. That is why I use a wire calculator to determine wire size for ampicity and voltage drop.

It is analogous to filling your tires with air. Volts = pressure, Amps = volume. To fill a tire you need more pressure in the air line than in the tire and you need a big enough hose to handle the volume of air. You can fill a tire with a tiny hose, but it will take longer and need much higher pressure for the same volume.

Simplified explanation, hope I haven't confused the issue.

-- Spiff

P.S. Looking good Seraphim

 

[wagoneer]

My 2 green river 6 volt AGM bats are inches away from my controller the roof solar panel on the other hand is 6 ft. away running #10 to the morningstar mppt 15 controller which will not accept any larger than #10 to the bats. Thanks for the help.

 

[Seraphim]

#10 is good for 30 amps #8 stranded is good for 50 amps, but I like to figure 20% for heat and resistance so the minumum would be #8 stranded. that said, there is the voltage drop problem, but his controller is almost on top of his batts so I would not be concerned with using #8.

That said it looks like his batts and controller are inside his coach, so the larger wire would be just a safety pillow to help with ones sleep

when it comes to wire and 12 volt, if you got the money, bigger is always better:angel:

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Seraphim, I have found that after a time that the roof connectors should be wiggled around a bit because they corrode, you'll know when your charge voltage starts dropping a little. I'm a solder, plastic tape and liquid tape man, myself. After I fasten down the lead in wires to keep them from blowing in the wind then I coat them with white roof coating to prevent UV damage. Higher elevations really zap wire coatings with UV rays.

Also have you thought about putting roof coating on your roof bracket screws? I usually lay a blob of silicon down under the bracket then screw through the silicon. I put a blob on the screw head and then coat the roof bracket foot and screw with roof coating. When you are driving down the road at 70 mph the wind load can push water under the brackets and around the screws. This can eventually rot your roof panel and release the screws, hence, screw through the silicon.

Your leads should not shock you, but will put a smile on your face if some how you get them connected through some light sheet metal.

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I forgot to take a photo, but I used Dicor self leveling lap seal over the screws and mounts. I talked shop at the RV repair, and they said that, using the Dicor, it wasn't necessary to put sealant between the mount and roof. Were I not in a time constraints, I probably would have anyway.

I had planned to seal the leads down with globs of Dicor, but hadn't comsidered painting them. I like the idea, as long as the paint isn't harmful to the rubber roof.

I'm kind of bugged about those big connectors, but they were quick and if they work, they work. Maybe later down the road. Once I know the system works I'll have time - somewhere warm - to make improvements.

I've a few touchups left to make, but nothing critical. Things I didn't finish up yesterday because it was too late and my muscles were stiffening up -*grin*

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The battery boxes need work - they don't seal properly now, so I'm going to cut holes for the sires, then seal them up with some compound. If they're not seal and charging, the gas alarm goes off...

 

[66788]

WARNING!!!!

When measuring the real estate on your roof to fit the panels, don't forget the mounting brackets add width to the panel. A 21" wide panel will need 24" of real estate to mount. Do not ask me how I know this. I tend to bite when I'm ticked off at myself lol.

It's not going to be a major problem for me, but it might be for someone else in their install, so I thought it really needed to be mentioned.

You could attach the 4 mounting brackets to the ends of the panels and still maintain your original width.

Just saying...

 

[Seraphim]

You could attach the 4 mounting brackets to the ends of the panels and still maintain your original width.

Just saying...

Good point. Have to drill new mounting holes in the frame, though.

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Been getting advice on another thread, and after listening to people and wading through the manuals, I've come to the conclusion there's a wiring problem. So I'll double check everything tomorrow. The positive panel connection at the controller doesn't feel as firm as the others, so I I have to unmount the controller to look underneath. Make sure I marked the positive wire correctly, push all the connections together..

Will see what I see.

 

[Seraphim]

Was having trouble getting the system to charge - indicated they panel's were disconnected. Checked everything, rechecked everything, tightened everything...

...then I considered the impossible. Remember how I marked the positive cable with a piece of tape, and remarked it on the bottom? Somewhere I goofed. On a whim I switched the panel leads to the controller and presto change - the $&*! Thing is charging. Only now, the panels are fused on the negative wire.

I am suitably embarrassed and you are all entitled to laugh. Once.

Anyway, the batteries are down to 93% (196 amps remaining, 15 to full charge). The controller was charging at about 7 amps on a very overcast day. Two hours I'll check the charge and see how it's going.

 

[SternWake]

Please do not take the battery monitor readings as 100% accurate.

The capacity of the batteries is always slowly diminishing, most monitors do not account for peukert effect when it starts counting down from zero amd large loads are not accurately recorded.
It does not necessarily mean zero AH from full was indeed a full charge, nor does it account for battery temperature and the how the battery capacity changes with it. The percentages remaining screen are really misleading too, and more so with an aged battery, and even more so if the voltage presets are too low and it thinks a 94% charged battery is 100%. 20 recharge cycles that reach only 94% will reduce the overall capacity the battery has to give. The monitor will state that the battery is 85%, but it could really be down at 70%, and the battery is screaming for an equalization charge to regain that lost capacity due to chronic undercharging.

The battery monitor observer has a few more tools available to notice decreased performance, but needs to be aware that the monitor itself is not always 100% accurate. Over time expectations of voltage under load for X amount removed, trends and tendencies, are either near expected, or lower than expected. When these lower observations occur it is usually time to break out the hydrometer and perform an equalization and re zero the monitor.

Having a charging source capable of doing 15.5v, preferably 16v is an issue when one has flooded batteries as 16V can do in 30 minutes what it takes 15.5v 2 hours to accomplish, and what 14.4v might need 36 hours to accomplish, and the goal is maxing out the specific gravity. Only when the SG is as high as it can go can the battery be considered 100%, and at this point the monitor needs to be rezeroed, and the observer should then watch the discharge cycle to see what voltage the battery can maintain under discharge, and use this as the performance benchmark.

That said it it still a great tool and a million miles ahead of a simple voltmeter, but over time you will notice that if it were 100% accurate, your expectations of voltage for x amount of amp hours removed, and how much amperage it takes to hold a certain charging voltage with X amp hours still to go, well these numbers will vary more than temperature and peukert can account for.

Re zeroing the monitor when the batteries are brimming full is wise, and reducing the amp hours of storage as the batteries age is wise too, but how much to reduce the programmed amp hours is pretty much a guess unless you are going to do a 20 hour load test on them, which is not worth the effort or the abuse on the battery to perform such a test.

MPPT controllers are more susceptible to voltage drop affecting output, than PWM controllers. I get a bit annoyed when I see x gauge wire is rated for x amount of amps so this gauge is fine, but the length of the total circuit is not accounted for, and voltage drop along that circuit is seemingly simply ignored as with battery charging, minimum voltage drop is directly related to charging performance, and ultimately battery longevity, and performance during that lifespan

A well performing charging circuit simply needs wire thickness well in excess of any wire ampacity chart, be it a RV converter/charger, a solar system, or an alternator feeding a distant house battery.

The ampacity charts are more a guide to how much you can pass through any given gauge wire before it heats excessively. This heat generated is simply wasted power. Thick wiring wastes less power.

Those who use ampacity charts to wire charging systems, have poorly performing charging systems. This poorly performing system might meet some people's needs 'just fine' but heavy users with the tools and knowledge to understand these things will realize their charging sources electrons are not getting to their batteries, but are going toward heating up a long length of too thin copper.

So when setting up a system, it is much better to allocate extra money for extra copper, as nothing is more frustrating than a solar system which should be able to feed 10 amps into a battery at high noon in summertime, yet maxes out at 7, those 3 amps just heating the wire en route to the battery because frugality, ampacity charts, and incorrect assumptions ruled the day when 'place order' was clicked.

Save money elsewhere. Copper is worth the extra $$ where batteries are concerned, and the ampacity charts should be ignored until it is time to decide how thick to wire that lightbulb.

Buy more copper now, or buy a lot more lead to go along with your frustration, later.

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Mainsail's 'how to' articles are a priceless source of info about all things electrical and battery related. I could basically stop typing in this forum regarding things electrical and just post links to his sites various chapters.

http://www.pbase.com/mainecruising/battery_monitor

 

[Seraphim]

Thanks Sternwake. I realize the battery monitor is providing a ball park figure - I just use it for general tracking of the system. I'm just going to look for postive movement from 93%. l don't care about extreme accuracy. The charger shows 14.8 volts pushing about 7 amps across #10 wire 18" to the battery. The monitor is showing the battery as charging, while still supporting a .2 amp phantom load. It probably won't be long until I switch to mppt, if the extra voltage used from the panels lets it charge that much quicker

 

[LeeRevell]

I keep seeing this, and feel without a definition, the term is a non issue. We who aren't electrical engineers have no context to understand it.
"peukert effect"
So for those of us with no reference to this term, here is the Wiki article:
http://en.wikipedia.org/wiki/Peukert's_law

It's still hard to understand really. Basically what I get is that the actual 'capacity' of the battery changes with different rates of discharge(?).

 

[Seraphim]

I tried to figure it out too, but my brain went fuzzy. Right now I'm just tickled pink the system's working.

The batteries are eight months old and have been float charging on shore power more often than not. Never discharged below 60%. Next sunny day I need to put the camper back in the truck, and pull it out of its shady parking spot to get a good idea of what's going on with its capability. Then I reconsider upgrading certain choices.

 

[Bela's Mom]

I thought about your wires also.....but.....well.....Sorry, I'm laughing!

Glad that you got it all sorted out!

 

[Seraphim]

I thought about your wires also.....but.....well.....Sorry, I'm laughing!

Glad that you got it all sorted out!

Hey - it's a laughable moment...

 

[akrvbob]

Much better a "laughable" moment than a "cryable" moment!

My rule of thumb s that every wire in the system connected to a positive post is either a red wire or has red electrical tape at every connection so I'm never confused.

The reason is simple, I am very easily confused!!! I have lots of "confusable" moments!
Bob

 

[Seraphim]

Much better a "laughable" moment than a "cryable" moment!

My rule of thumb s that every wire in the system connected to a positive post is either a red wire or has red electrical tape at every connection so I'm never confused.

The reason is simple, I am very easily confused!!! I have lots of "confusable" moments!
Bob

But I marked the positive cable with tape!!!! Lol

It just wasn't the positive cable, so I guess I'm confusable too...

 

[Spaceman Spiff]

My convention is:
- Any positive wire coming directly from the battery is red,
- Positive wires into and out of charge controller are red,
- All and only ground wires are black, (only exception is the positive cable from solar panels is black ('cuz that's what came from Renogy and replacing it didn't seem worth the bother),
- All other colored wires come from fuse box and are hot,
- All except ground wires and very short wires are labeled with what is on the other end (royal pain in the tush!!!)

I have had to tear too many things apart trying to figure out a wiring problem and have found that the time spent up front labeling saves much pain later.

-- Spiff

 

[Optimistic Paranoid]

It's still hard to understand really. Basically what I get is that the actual 'capacity' of the battery changes with different rates of discharge(?).

People like to talk like a "storage battery" is a container holding electricity. It's actually a generator powered by chemical reactions.

And chemical reactions, by their nature, are a bit variable depending on temperature, pressure, and other variables.

Did you know that if you take X amp hours out of a fully charged battery, you have to put X + 10% amp hours back in to bring it back to full charge?

Regards
John

 

[LeeRevell]

Did you know that if you take X amp hours out of a fully charged battery, you have to put X + 10% amp hours back in to bring it back to full charge?
Regards
John

No, I did not know that. My electrical/electronic experience is from the military, both USAF and USN. There, the training is very specific to the job we are going to be doing. The Navy's BE&E (Basic Electrical & Electronics) school has virtually nothing on battery systems, because our gear is not concerned with that.
The "A" and "C" tech schools are even more specialized to the specific equipment we are trained to work on. These are shipboard and installation systems using main power.
The only thing we learned for batteries was basic series and parallel hook-ups and polarity.

I am learning a LOT reading these forums! Thanks, folks!

 

[Seraphim]

People like to talk like a "storage battery" is a container holding electricity. It's actually a generator powered by chemical reactions.

And chemical reactions, by their nature, are a bit variable depending on temperature, pressure, and other variables.

Did you know that if you take X amp hours out of a fully charged battery, you have to put X + 10% amp hours back in to bring it back to full charge?

Regards
John

Thanks for that bit of information. It will help me figure things out