Charge controller and gauge of AWG wire

[OfftotheRaces]

I am new to this game and I am setting up a portal system for my tent trailer. I have purchased 2 100W panels and will initially be using them to maintain my 12V deep cycle group 24 marine battery. I am looking to upgrade this to 2 6volt agms in the future. The charge controller will be located on my solar panel stand that I made, so no issues with voltage loss here. However the panels are portal depending where the sun is, so I am allowing 25 feet distance between the controller and battery. This will probably will require 6 Awg or less wire from what i have read. My question is will connecting such a large diameter wire pose any issues with controllers. Is there a preferred connector that I should use?

Thanks OfftotheRaces

[Sunking]

Gauge is not the issue mas it cam be as large as needed, the controller doesn't care. Only time th esizze becomes a problem if it is too small. The real issue is locating the controller with the panels instead of the batteries. The higher voltage should be used for the longer runs, not lower voltages.

[Mike90250]

Most controllers, if you look in their specs, will state what size wire their terminals will accept. You can always do a splice for the last foot, and use a smaller wire that will fit the controller.

[PNjunction]

The charge controller will be located on my solar panel stand that I made, so no issues with voltage loss here. However the panels are portal depending where the sun is, so I am allowing 25 feet distance between the controller and battery

One reason for putting the controller very close to the batteries is that most quality charge controllers have built-in temperature-compensation sensors, which is very important. By placing the CC near the battery, the temp-comp of the CC will be much more accurate than having it out near the panel - even if shaded out there.

Typically your batteries will be in the shade or someplace cooler than that of the panel in direct sunlight. On the other hand, perhaps your batteries will be in a warmer location than out in the freeze / wind of a cold climate where your panels are. Here again, temp comp is most accurate when the CC is in the same environment as the battery.

Some CC's also allow for even greater accuracy with "on-battery" temp probes, and you probably don't want to be running an additional 25 feet or more of that back from the battery to the controller.

Example - my little portable Renogy 100w folding panel comes with a little pwm charger mounted on the back of one of the panels. That is not the ideal location, because my batteries aren't sitting just underneath the panel, but further out and in the shade where temps are different.

So keep the controller near the batteries.

[OfftotheRaces]

Charge controller

Gauge is not the issue mas it cam be as large as needed, the controller doesn't care. Only time th esizze becomes a problem if it is too small. The real issue is locating the controller with the panels instead of the batteries. The higher voltage should be used for the longer runs, not lower voltages.

"Thanks for the help I will look into moving the Charge controller"

OfftotheRaces

[OfftotheRaces]

Charge controller

Most controllers, if you look in their specs, will state what size wire their terminals will accept. You can always do a splice for the last foot, and use a smaller wire that will fit the controller.

"Hopefully it will take it and if not I will splice or replace the controller"

Thanks...OfftotheRaces

[OfftotheRaces]

Charge controller

One reason for putting the controller very close to the batteries is that most quality charge controllers have built-in temperature-compensation sensors, which is very important. By placing the CC near the battery, the temp-comp of the CC will be much more accurate than having it out near the panel - even if shaded out there.

Typically your batteries will be in the shade or someplace cooler than that of the panel in direct sunlight. On the other hand, perhaps your batteries will be in a warmer location than out in the freeze / wind of a cold climate where your panels are. Here again, temp comp is most accurate when the CC is in the same environment as the battery.


Some CC's also allow for even greater accuracy with "on-battery" temp probes, and you probably don't want to be running an additional 25 feet or more of that back from the battery to the controller.

Example - my little portable Renogy 100w folding panel comes with a little pwm charger mounted on the back of one of the panels. That is not the ideal location, because my batteries aren't sitting just underneath the panel, but further out and in the shade where temps are different.

So keep the controller near the batteries.

"I to have renogy panels and they come wired. They are fairly thin so I imagine they don't meet the specs. So would I just splice these wires into the proper sized wires?"

Thanks OfftotheRaces

[PNjunction]

For 25 feet *one way*, with about 10a current, 6 gauge would be fine, although even 10 gauge wouldn't be so bad since this is not a critical application.

I'm assuming your panels are "nominal 12v" panels, that actually have a 17-21v ocv rating, and are paralleled together.

In either case, when you search for something like solar-dc-wiring-length-charts, be sure to note if their tables are one-way or two-way (out and back) measurements.

For connectors, MC4's are commonly used. Instead of making them yourself, some like to just cut up a jumper that already has mc4's at both ends.

Of course for diy stuff many use "Anderson" connectors. You can crimp them yourself, or possibly get jumpers premade that you can cut from Powerwerx.

I believe the Renogy folding suitcase actually uses a non-standard guage somewhere in between 10 and 12, and I don't mess with it because my infrequent portable needs don't justify my modification to do it right. But it's on my list of things to do, like increase the gauge, move the controller near the battery etc.

[OfftotheRaces]

Charge controller

For 25 feet *one way*, with about 10a current, 6 gauge would be fine, although even 10 gauge wouldn't be so bad since this is not a critical application.

I'm assuming your panels are "nominal 12v" panels, that actually have a 17-21v ocv rating, and are paralleled together.

In either case, when you search for something like solar-dc-wiring-length-charts, be sure to note if their tables are one-way or two-way (out and back) measurements.

For connectors, MC4's are commonly used. Instead of making them yourself, some like to just cut up a jumper that already has mc4's at both ends.

Of course for diy stuff many use "Anderson" connectors. You can crimp them yourself, or possibly get jumpers premade that you can cut from Powerwerx.

I believe the Renogy folding suitcase actually uses a non-standard guage somewhere in between 10 and 12, and I don't mess with it because my infrequent portable needs don't justify my modification to do it right. But it's on my list of things to do, like increase the gauge, move the controller near the battery etc.

"Thanks for the advice, I think I will go with the 10 AWG. Well I am a step closer and will need now to read over all the post on calculations on power usage and if is worth while buying two 6VOLT batteries and putting them in series.

OfftotheRaces"

[PNjunction]

That's a great idea. If your marine battery isn't totally shot, you can get some good practice in on that before splurging on something like a T105RE or other golf cart battery. Obviously they aren't in the same league, but if you are going to make mistakes, do so on the "practice" battery first.

A good charger that will actually let you know if your marine battery is even serviceable would be a Tecmate-Optimate 6, as you get test results afterwards in a pretty straightforward fashion. Most other vehicular type chargers either don't test, or don't let you know. AND, you can obviously use it for more than just keeping your marine battery in shape.

Just a thought, since lately that has become more of a valuable tool than just a regular dumb/smart charger.