hooking up solar plug

[2020]

I'm ready to hook up my solar panel plug to the batteries in my Grandby. The camper shipped with the wires to the plug unconnected. Before I do anything foolish, can anyone guide me as where to connect the wires? I assume they connect directly to the battery terminals, correct? I have two of the AGM deep cycle batteries. Anything special I need to know?

Thanks.

 

[longhorn1]

That would be the best way to fry your batteries. You need to install a solar controller and have the the solar plug wires connect directly to the controller with required fuses. I have 2 AGM batteries and 100w solar on the roof. The 100w panel and the solar plug on the rear of my camper go to the solar controller. I'm by no means some electronics junkie, but in discussions with Brenda about a solar in a bag, I was told to get the Zamp portable without its own controller, since the plug is wired directly to the solar controller. When I spoke to the distributor for Zamp yesterday and today, he stated that without the controller on on the portable panel, if wired directly to the battery, there is a high probability that the battery will get fried. My 2 cents worth. jd

 

[2020]

I have the controller. It is already connected to the solar panel. When I am ready to go I have only to plug the controller into the rear solar plug on my Grandby. Right now I just want to connect the rear solar plug on the camper to the batteries. The camper was delivered with the plug wires not connected to the batteries. The wires to the plug are right there in the battery compartment. I recall the FWC dealer telling me that all I needed to do was connect the wires to the terminals. I just want to confirm that I am doing it right. The batteries are connected to each other parallel, so it doesn't really matter which battery I connect the plug wires to, correct?

 

[PaulT]

I'll third what they said above. The only exception would be if you have no existing solar controller and your portable panel has a built-in solar controller attached to the panel. In that case you could connect directly to the battery.

An additional reason is that the solar panel may not have a blocking diode to prevent reverse current. There will be one in the solar controller. The blocking diode keeps the battery from applying power to the panel at night when no sun shines. The least bad thing that would happen is that the battery drains through the pv panel at night.

Well you posted while I was editing my post. I would still place a fuse in the positive lead to the battery because one day, you will realize that you can plug in some power consuming device to the solar panel socket on the camper to use outside your camper and you do not there to be a direct connection to the battery.

Paul

 

[longhorn1]

I have the controller. It is already connected to the solar panel. When I am ready to go I have only to plug the controller into the rear solar plug on my Grandby. Right now I just want to connect the rear solar plug on the camper to the batteries. The camper was delivered with the plug wires not connected to the batteries. The wires to the plug are right there in the battery compartment. I recall the FWC dealer telling me that all I needed to do was connect the wires to the terminals. I just want to confirm that I am doing it right. The batteries are connected to each other parallel, so it doesn't really matter which battery I connect the plug wires to, correct?

Again both FWC and Portablesolardiaz warned about connecting a solar panel directly to the battery. They both stated that it would damage the batery(s). You should connect the plug-in to the controller.

 

[norcalhawk]

2020,

If I'm reading your post correctly, all you need to do (as you stated, both (pos/neg) wires are there at the batteries and everything else is hooked up) is install a 30A fuse (if not already there) on the positive wire and then connect the red to positive terminal and black to the negative terminal. That should do it! Good luck....

 

[PaulT]

Again both FWC and Portablesolardiaz warned about connecting a solar panel directly to the battery. They both stated that it would damage the batery(s). You should connect the plug-in to the controller.

I have the controller. It is already connected to the solar panel. When I am ready to go I have only to plug the controller into the rear solar plug on my Grandby. Right now I just want to connect the rear solar plug on the camper to the batteries. The camper was delivered with the plug wires not connected to the batteries. The wires to the plug are right there in the battery compartment. I recall the FWC dealer telling me that all I needed to do was connect the wires to the terminals. I just want to confirm that I am doing it right. The batteries are connected to each other parallel, so it doesn't really matter which battery I connect the plug wires to, correct?

longhorn1,

His pv panel has a charge controller mounted on the panel external to the camper so he is good to go except for fusing the wires from the rear wall plug to the battery. Fuse is required because the pv socket on the back of the camper is otherwise vulnerable to providing the opportunity for a direct short across the battery.

Paul

 

[2020]

longhorn1,

His pv panel has a charge controller mounted on the panel external to the camper so he is good to go except for fusing the wires from the rear wall plug to the battery. Fuse is required because the pv socket on the back of the camper is otherwise vulnerable to providing the opportunity for a direct short across the battery.

Paul

Thank you, Paul. Fusing the wires sounds like good advice. Stuff happens, after all.

 

[Hobart78]

My 2014 Hawk came with solar plugs on top and back with wires from both ending in the battery compartment. Each wire bundle is labeled identifying it as from the top or back plugs. Mine were labeled wrong at the factory as in the back plug wires were labeled as coming from the top plug.

George

 

[longhorn1]

longhorn1,

His pv panel has a charge controller mounted on the panel external to the camper so he is good to go except for fusing the wires from the rear wall plug to the battery. Fuse is required because the pv socket on the back of the camper is otherwise vulnerable to providing the opportunity for a direct short across the battery.

Paul

I missed that. Thanks Paul. That came to mind and I looked but didn't see that. Longhorn

 

[Fallbrook]

For sure use a charge controller and fuse it right. Those damn AGM batteries aren't cheap (we just got 4 at Bass Pro for $200 each), not to mention how much fun battery short fires are.

 

[2020]

OK my solar plug is now connected. I put a put a 30 amp fuse on the wire from the back plug to the positive terminal as recommended. I used a fuse holder for 12v DC with 10 gauge wire rated for 30 amps. My guy noted that the wiring FWC installed for the solar plug is 14 gauge which is rated for only 15 amps. He recommends that I should use a 15 amp fuse because a slow short could cause the 14 gauge wires to heat up considerably before it blows a 30 amp fuse. He says that if the 15 amp fuse blows from normal use I can go up in increments and try a 20 amp fuse.

Any comments/advice about this?

Thanks.

 

[ntsqd]

DC ampacity is figured differently than the NEC. According to my Anchor reference booklet 14 ga. max's out at 10A in a 10 foot or less total circuit length (including ground path) if you want a voltage drop of 3% or less. Which in solar you do want. Can double the length if you can limit the circuit to 5A.

 

[2020]

What I am wondering is why are folks on this forum recommending a 30 amp fuse if the FWC wiring can only handle 15 amps without heating up?

 

[Happyjax]

AWG - American Wire Gauge Current Ratings

This page has a chart for wire gauge/current capabilities. It calls for max amps of 24 for 14 gauge wire with a single core (which is really for house wiring) and as low as 7.5 amps with lots of strands. I would NOT use a 30 amp fuse. I personally think that 14 gauge is too small for that job and if it was my setup I would go with 10 gauge, 12 gauge minimum. There would be less voltage drop and less heat buildup in the wire.
When it comes to fusing I would err on the safe side. A 15 should handle a 100w solar panel, if that is what you are using, and if your wire is 3 core you would be ok by the chart. As you can see as the cores increase the amperage decreases so make sure you know what wire you are using.
BTW using 10 gauge wire on your 30 amp fuse holder is worthless if you are taking it into 14 gauge wire. Weakest link syndrome.....
Good Luck

 

[ntsqd]

I suspect that the 30A fuse recommendation was made for the power of the panel(s) without consideration or knowledge of the tiny wire size in the circuit. That was unexpected, the assumption here was a 10 ga. minimum wire.

The crucial difference between most NEC (Nat'l Electrical Code) based charts and the charts that should be used is that they are for AC, not DC. AC allows the wire to cool during the vast majority of the time that the circuit is not at or above the "RMS" current. The NEC's values are set such that the length of the circuit is not a factor.

A true DC chart is a grid with current and circuit length deciding the minimum wire gauge. This is the sort of ampacity chart that should be referenced for DC voltage:
http://www.ancorproducts.com/en/resources/three-percent-voltage-drop

If a 10% Voltage drop is acceptable then:
http://www.ancorproducts.com/en/resources/ten-percent-voltage-drop
I would strongly caution against using the 10% chart with a solar system, you want everything that you can get. Can use it for things like light circuits etc.

 

[Happyjax]

I suspect that the 30A fuse recommendation was made for the power of the panel(s) without consideration or knowledge of the tiny wire size in the circuit. That was unexpected, the assumption here was a 10 ga. minimum wire.

The crucial difference between most NEC (Nat'l Electrical Code) based charts and the charts that should be used is that they are for AC, not DC. AC allows the wire to cool during the vast majority of the time that the circuit is not at or above the "RMS" current. The NEC's values are set such that the length of the circuit is not a factor.

A true DC chart is a grid with current and circuit length deciding the minimum wire gauge. This is the sort of ampacity chart that should be referenced for DC voltage:
http://www.ancorproducts.com/en/resources/three-percent-voltage-drop

If a 10% Voltage drop is acceptable then:
http://www.ancorproducts.com/en/resources/ten-percent-voltage-drop
I would strongly caution against using the 10% chart with a solar system, you want everything that you can get. Can use it for things like light circuits etc.

Good chart

 

[2020]

My solar panel is 200W. The plug was installed by FWC at the factory with 14 gauge wire. I realize that the 30 amp fuse holder is overkill connected to that circuit, but it will work fine with a lower rated fuse. Now I am wondering if the 200W panel may be too powerful for the 14 gauge wire.

I suppose upgrading the whole circuit to 10 gauge would be best. Does anyone have experience rewiring the FWC factory solar plug from rear wall to batteries? Any tips/advice for this would be useful.

Thanks.

 

[Ethergore]

So does this mean those FWC with 14 g wire should put no more than 1 panel on their roof safely? Or more specifically about 100 w?

I'm assuming about 20 ft of 14 g wire from panel to battery at 5-6 amps in good sun.

I guess you can get around this by running two panels in 24 volts.

 

[DrJ]

I would not worry about the 200 watt panel and the FWC wire.

There is of course a voltage drop that occurs from the solar energy generated at the panels and the solar charge controller.

This is affected by the gauge of the wire, length of the wire, type of wire and the amps/voltage being carried across the wire.

Your panels are likely to transfer 12-20 volts at a time depending upon the voltage and type of panel.

A higher voltage means less voltage drop across a smaller gauge wire than most people think of in their calculations for this.

I have 3 panels - total of 340 watts - and draw around 15-17 amps on good days.
Panel voltage is usually between 16-24 when it reaches the solar charge controller.

200 watts should be no problem for you.