Yostfmx Posted June 26, 2008 Share Posted June 26, 2008 I have a new Harbor Freight 45 solar panel on my motorhome and am doing the wiring. The controller that comes with it is mounted right above the door (door is a right behind the cab) very close to the panel itself so thats no problem, but now to get to the battery from the controller is about 20' of wire! Is that going to cut the power I'm getting from the panel? I could if I really have to remount the battery closer, but its still 16' of wire to get it there. The other thing is, in the solar kit it has battery wires in it but they'er only 3' long and 18 gage, I'm using 16 gage. Anyone know anything about this? Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 27, 2008 Share Posted June 27, 2008 What is the wattage of the panel? The larger the better the loss at 12 volts is pretty high use #10 or #12 if you can. Quote Link to comment Share on other sites More sharing options...
Yostfmx Posted June 27, 2008 Author Share Posted June 27, 2008 Sorry, its 45 watt. 10 or 12 gauge wire? Is that what you mean? I got it wired today with 16 gauge, and the wires are 17 feet long from the battery to controller. Quote Link to comment Share on other sites More sharing options...
WME Posted June 27, 2008 Share Posted June 27, 2008 Use a good voltmeter and check the voltage at the controller and the battery. .5v is to much loss. I prefer 10 ga wire too and the controller as close as possible to the batteries. That way the voltage drop is on the 18v from the panel and you can still get 14.5v to the batteries. Quote Link to comment Share on other sites More sharing options...
Yostfmx Posted June 27, 2008 Author Share Posted June 27, 2008 Yea but the contoller has to go where it is cause my lights plug in to the controller. I'm going to get 10 gauge right now. Some people on this solar panel forum said the samething as you, "controller as close as possible to the batteries" but then someone said that # 12 or # 10 would be ok and work fine. I am very new at all this... Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 27, 2008 Share Posted June 27, 2008 It’s typical for manufactures to use small wires but at 3’ the loss is minimal but putting your battery on the roof is not particularly handy and yeah putting the controller near the battery is a good ideal too. # 10 awg would be your best bet. 45 watts is a nice figure that should do a good job for you. Quote Link to comment Share on other sites More sharing options...
Yostfmx Posted June 28, 2008 Author Share Posted June 28, 2008 Its all wired up now, but no battery yet. #10, 18 feet long. Yea I hope it all works cause its China crap from Harbor Freight, but it was only $179.00 on sale. Can't beat that... If it works haha... Quote Link to comment Share on other sites More sharing options...
Trav's 86' Sunrader Posted August 12, 2008 Share Posted August 12, 2008 This is the difference and trade off of AC vs DC as I am sure you may know. There are calculations that you can use to determine the gage wire you will need based on the distance that the electricity must travel. I have a book on it and a degree in Engineering if you want to work on something more specific. I apreciate all your posts. Quote Link to comment Share on other sites More sharing options...
futar Posted August 13, 2008 Share Posted August 13, 2008 It's all about current. It's called I squared x r loss. That's current times resistance. That is how heat is created. If you create the same wattage (current times voltage) by higher voltage times lower current, you reduce the heat loss. That's why high intensity lamps work so good, they're low voltage times higher current. It's also why power lines are 110,000 volts. To reduce losses. Now I betcha didn't know this. Auto wire of the same gauge is different than house wire. How you may ask? It has more and finer strands. That is because electricity flows around the circumference of wire. So if you use more strands for the same gauge, there's less heat loss and higher current capacity. Your 45 watt solar panel generates 4 amps so size accordingly. Good old Harbor Freight. Quote Link to comment Share on other sites More sharing options...
nibs Posted August 13, 2008 Share Posted August 13, 2008 The best deals on PV panels are usually found around quartzite and Yuma. We bought a 120 watt panel made by Sharp for $375 new in Feb 08. Personally Yost, I would put the controller by the battery and bring a wire back from the battery for the lights. The panel volatage will climb (with some loss) until it overcomes line loss and controller resistance, but once you put it through the controller, the voltage is limitted so you will get line loss. Quote Link to comment Share on other sites More sharing options...
states02 Posted December 9, 2009 Share Posted December 9, 2009 Its all wired up now, but no battery yet. #10, 18 feet long. Yea I hope it all works cause its China crap from Harbor Freight, but it was only $179.00 on sale. Can't beat that... If it works haha... I'd love to see the mounting you used. I"m getting ready to put a HF 45 w solar on my Dolphin. Was thinking about setting up a charge trailer to tow behind the rig and then I could put the trailer in the sun and the Dolph in the shade. email me if you have some pics learn7peace@yahoo.com Quote Link to comment Share on other sites More sharing options...
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