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offgrid 
Senior Member 
Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
 Topic: Solar port 17 1/2 179Posted: 19 Jun 2019 at 3:06pm |
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Yep, it matters. The fuse is there to stop the wire from overheating if it shorts out. The solar module and controller are current limited, if you short them out nothing will happen. OTOH we all know what happens if you short out a battery. So, put your fuse in the positive conductor at the battery end.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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Subzilla
Senior Member
Joined: 23 Jan 2017 Location: Concord, NC Online Status: Offline Posts: 302 |
Posted: 19 Jun 2019 at 2:03pm |
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Bringing this thread back up for my question as I'm not as electrical minded as most of you folks. Just purchased the Renogy Solar Suitcase and thinking about the fusing. Planning to use the RPOD solar port......should I put a fuse right at the batter connections or closer to the controller? Seems if there is a problem coming from the controller, you would want a fuse there but I understand having one at the battery. Or does it matter?
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Mark
Concord, NC 2017 RP 179 "Podzilla" 2011 Silverado 1500 4X4 |
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offgrid
Senior Member
Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 28 May 2019 at 4:22pm |
That is a very good point. Most solar modules, including all larger modules which are generally used for higher voltage applications, have bypass diodes in them. The bypass diodes are meant to "bypass" current around groups of cells in the module that are shaded. This both mitigates against shading losses but more importantly protects the shaded cells from getting overheated by having current forced through them. If you connect one of these modules in reverse across a battery you will blow the bypass diodes out of it immediately. The point is, don't connect a solar module across a battery in reverse. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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podwerkz
Senior Member
Joined: 11 Mar 2019 Location: Texas Online Status: Offline Posts: 966 |
Posted: 28 May 2019 at 4:00pm |
Some solar controllers are reverse polarity protected, and some are not. Some solar controllers are hard-wired to be negative ground ONLY. If you apply positive battery voltage to the negative side of the controller, AND you have other wires connected properly or improperly, you might blow fuses, let some magic smoke out, or worse, have un-contained current flow from the battery going places you dont want it to go. Likewise, the diodes and/or cells in a panel can be damaged if they are hooked up in reverse, especially when connected directly to a battery, as in the case with using smaller panels. I would not advise a wide internet audience with no way of you knowing what they are hooking up, that 'it wont hurt anything'.... Cuz, maybe it wont...but maybe it WILL. |
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r･pod 171 gone but not forgotten!
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offgrid
Senior Member
Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 28 May 2019 at 10:59am |
I suspect that your telecom sites weren't inspected by the AHJ. Go try to get a DC solar installation on a residence approved without following the NEC (including conductor color conventions) and see how far you get. I can assure you not very far unless the inspector is clueless.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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offgrid
Senior Member
Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 28 May 2019 at 10:52am |
Hot red and black neutral are typical automotive conventions, not code. They are not the standards for electrical systems in homes or RV's. Its not a DC thing, the NEC doesn't distinguish AC from DC in this regard This causes lots of confusion for everyone.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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GlueGuy
Senior Member
Joined: 15 May 2017 Location: N. California Online Status: Offline Posts: 2629 |
Posted: 28 May 2019 at 10:37am |
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I will disagree with the notion that color on DC circuits means anything to anyone unless you were there to witness the installation.
I've been involved with telecom equipment for quite a while, and some telecom equipment is positive ground, and some is negative ground. On on the installations I've been involved with, I've used red to mark positive, and black to mark negative. Curiously, that means that some installations have the black tied to ground, and some have the red tied to ground. The really interesting sites are the ones that have a mix of positive-ground and negative ground equipment. As a result, we usually have two "hot" leads; one positive and one negative. In those installations, we usually mark the negative "hot" with blue wire. Bottom line is that DC circuits are all over the map. Color conventions have come, and color conventions have gone, and they are all different.
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bp
2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
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offgrid
Senior Member
Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 28 May 2019 at 10:30am |
I have to continue to disagree.
Solar charge controllers have voltage comparator circuits in them, they are not necessarily polarity protected. Most are nowadays, but don't count on it. As a solar engineer (40 years, NOT still working!) I've seen plenty where the installer found out where they've hid the smoke by installing them wrong. I agree no one should ever assume what wire colors indicate, always check, but the Code does call for white to be neutral, and there is a reason. Trust but verify. if someone flips the white wire to the battery positive terminal and then someone else shorts that wire to the chassis they'll know in a hurry. i fully agree that there should be a fuse in that circuit. I've removed mine as I don't use it, otherwise it would be fused too. Marking is allowed for ungrounded conductors but I don't believe it is for a neutral less than 4 AWG under 200.6. But I could be wrong,let me know. Besides, by the time you pull the port to mark the wires you can simply rewire the connector on the solar controller you are connecting to it, and that leaves the wire colors consistent and compliant. In any case, its is my understanding that there are more RV fires in the 12Vdc circuits than there are in the 120/240Vac ones. If so, the reason is most likely that folks don't feel confident working on 120V circuits yet somehow 12V ones are OK. There is no shock hazard but there certainly is a fire hazard, perhaps more so than in 120V wiring because of the high currents involved. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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SteveA
Groupie 
Joined: 19 Jul 2017 Location: Sandpoint Id Online Status: Offline Posts: 56 |
Posted: 28 May 2019 at 9:41am |
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They were dedicated on my Pod as well and had the exact same experience as voisj. I plugged in a solar panel I had used on my former coach into the Zamp port and …… no charge... no blown inline fuse (on my panel) …..no nothing. I then traced the wires from the port to the battery only loosing sight of it a couple of times to make sure there were no breaks and all was good. This is what prompted my thread. I do VERY much appreciate the input from all and understand that in a home 120 ac white is ALWAYS a neutral. However these pods don't always follow the rules, 12v should always be "hot" red and black "ground" so the red and white leads from the Zamp port threw me a bit as I'm not as familiar with DC. I was out camping without my volt meter so a simple test wasn't an option. I'm not suggesting anyone here willy nilly swap wires on anything but on my pod it was the solution. Again, thanks for all your input,
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2017 179 1/2
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voisj
Senior Member
Joined: 19 Jul 2016 Location: San Luis Obispo Online Status: Offline Posts: 471 |
Posted: 28 May 2019 at 9:23am |
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(Quote from OffGrid) No. This post is doubly wrong. 1) Not all solar charge controllers are reverse polarity protected, and some that claim to be aren't. One should never just connect electronics up to a circuit with unknown polarity and hope things are OK. 2) Just because a circuit is "dedicated" doesn't open the door to miss wire it. If your electrician did that in your house to say your "dedicated" electric stove circuit you'd probably lodge a complaint to the state contractor's board, and rightfully so. The color code means something. No one knows what that circuit might be used for in future. Its a code violation and an accident waiting to happen. Electrical circuits are not that hard to work with but there are basic tools needed and guidelines to be followed. If you don't know what those are and how to do it properly then get professional help, same as you would for anything else. OG, 1. Small charge controllers are by their nature are polarity protected. both my harbor freight and Renogy have been plugged in reversed (different rv's, wired different) But you are correct, test first, things should ALWAYS be plugged in properly the first time, I'm just a dork. As an electrician (40yrs, still working) I disagree. We use marking tape to mark wires that must be used for other than their intended purpose. (3 way and 4 way switch circuits are a prime example) also main service drops (three black wires,ones a neutral), and in my pod I have found black ,white and bare wires as ground. Never assume. The two large wires that run under the pod from the battery to the port are all by themselves, not run with, or connected to, any other wires. and its 12v DC not 110 ac, if someone cuts or bites into it they wouldn't even know. (Side note; there is no fuse on these wires, which scared me and I put a 30 amp fuse on it at the battery, everyone should. if this wire gets grounded somehow (cut by a rock/branch) this wire could easily cause a fire, and/or ruin a battery.) If someone down the line is going to, find ,cut and use this wire for something other than it's intended purpose they would have know its source to turn off power to it or know what they are tapping into. properly marked this isn't an issue. You could pull the port and swap the wires at the port, but in my opinion not necessary. I did forget to mention in the op to mark with red/white tape. Yes, my comfort level with wiring is WAY different than most, and you are correct, if possible always follow standards. And if you are not comfortable with wiring have a professional do it. but some things have leeway and a dedicated 12v item like this, done properly, is still standard compliant, and safe. cheers John |
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Solar port 17 1/2 179
