Stopped by the orchard tonight and checked the aluminum frame of the solar panel. Although I couldn’t sense anything with my hand, my cheap tester registered up to 1000 volts when I grounded the tester and touched the alum frame with the positive. It was pulsing in synch with the charger.
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Interesting. Where did you have the test meter ground, in the dirt, at the ground of the fence charger, elsewhere?
Might be interesting if that meter would show any similar voltage on the + or - leads from the panels.
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Steve,
The PV frame isn’t grounded. It’s just screwed into the wood roof of the wooden box I built to house all the components.
The two wires for the PV come out of the back and go through a hole I drilled through the roof to connect to the components inside the wooden box.
I don’t have a tester, but I can clearly feel the pulse of current when I touch the frame of the PV and the ground is wet. It’s a pretty good tingle.
I didn’t know that. This one must have one of the electrical connections somehow in contact with aluminum frame, or it’s arcing across somewhere, although I don’t hear an arc.
I figured the problem is with the charger because the PV frame pulses with the charger. But what you say makes sense. The charge controller is probably also energized from the fence charger, as well. But the case of the charge controller is plastic so I can’t feel anything on the charge controller.
I assume the current is backfeeding through the fence charger, through the charge controller to the frame of the solar panel. My biggest concern is that it will eventually hurt the charge controller?
I don’t know much about PVs, so I don’t know if it will hurt it or not.
On a completely different unrelated subject I wanted to mention that the underground wire I’ve used as a lightening choke (coil of insulated wire hanging on the left of the wooden box in the picture above) is not good wire.
This is another product I bought from Kencove (very disappointed with most of their products). I can grab that insulated coil of wire and touch the ground and feel a pulse of current. So my guess is that the insulation is not good enough to keep voltage from leaking through it. This wire is supposed to be rated for underground electric fence.
If this wire were buried, it would leak energy into the ground, thereby reducing some of the energy of the electric fence.
I am not sure why you have a pulse on the PV frame ?
But it’s possible your hot wire output from charger is “ inducing “ a current into other wires in your box.?
May try moving the black 3 switch strip to the right side of charge controller , and move what I think is your power supply wire So that it goes over the top of fence charger . So , essentially keeping everything spatially separated from your hot fence wire coming out of the fence charger . You may just have a induced current ?
I hadn’t considered the possibility that. I wondered if there was an induction current inside the fence charger, but hadn’t considered the hot wire output inducing current into other wires.
One of the things you have me thinking of is the lightening choke I have hanging on the left side of the wooden box. It’s basically a pretty good coil of wire with the intended purpose of producing a magnetic field to help prevent lightening from coming back through the hot wire and frying the fence charger.
I would think it would be too far away from the solar panel frame to induce a current there, but I don’t know how close metal has to be to induce a current from a magnetic field? I know the high electric transmission lines which carry 100,000 volts will induce a current in the tomato cages below them, a distance of at least 40’.
I guess one quick way to determine if the hot wire for the electric fence is inducing a current is to simply unhook that wire from the fence charger. Turn the fence charger on and see if the PV frame is still energized. If so, then I would think it would have to be a backfeed from the fence charger itself, or some induced current inside the fence charger box?
I had wondered if part of the problem was that the metal bracket I built to hold the three toggle switches had a switch somehow energizing the bracket, and causing part of the problem (They are metal cased switches.) I wouldn’t expect it to be the whole issue because it wouldn’t account for the energized pulse of the PV frame. I unhooked the solar panel switch from the bracket to see if that made a difference. It didn’t. The solar panel was still energized every time the fence charger pulsed.
I thought about taking my amp meter and hooking it up to various wires to see what other wires are pulsing with the fence charger.
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I have been thinking about that coil too .
It’s my understanding that induction coils can be made of insulated wire , and still induce a current . No mater how good the insulation is ? Or at least that’s what “ I think” I understand. Not sure really about all this ? May want to remove that coil to see if it makes a difference ?
That’s true. In fact all wires in motor windings are insulated, otherwise the wire wouldn’t pass through the loops of wires and make an electromagnet, or it would make a very weak electromagnet. The insulation on the wires is so thin, it looks like they are uninsulated. Some people call it varnish, but just a slang term for a clear thin insulation (or at one time perhaps they used actual varnish as an insulation).
The insulation needs to be thin to get sufficient wraps of wire in the windings. That’s generally one of the more common things which go wrong in a motor. If the motor overheats and gets too hot, it burns through the insulation in the windings and shorts them out.
So you are correct, insulation has basically no effect on the induction of a magnetic current.
I think all I need to do to test this is to unhook the hot wire from the fence charger, thereby making any hot fence wires inside the box or outside completely dead. The fence charger would still be running, just without any wire attached to it. Then I should be able to tell if the hot fence wire, or lightening choke, is inducing the current felt on the PV frame.
Thanks for the idea. Even if it doesn’t solve the problem, at least I’ll know then it’s coming from inside the fence charger.
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Other thoughts about fences …
You said you did not have a tester .
I believe a tester is very important !
I use one with flashing lights always on the fence ,put in a shaded box that you can look at from your vehicle when you pass to see how many lights are blinking.
Fences short out , usually from a encounter with a animal that just had the BJesus knocked out of it , moving wires / insulators in a attempt to retreat.
Not only is a shorted out fence ineffective, it can drain , ruin a battery , on a solar powered set up.
Isolating sections of fence with switches can save a lot of trouble shooting time . Switching off sections, and testing each with a digital meter can help find where the trouble spot is .
Also , a AM radio tuned between stations , will usually click when near a dead short to ground,can help find shorts that may be overlooked visually. Really handy !
Or , you could just grab it every morning as a way to start the day ! Making sure it’s hotter than coffee .
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Some good ideas.
So far, I’ve been testing it with a short piece of insulated wire. If it arcs about 1/4", that seems to be about right. I have had a broken insulator on a corner. And once it was shorting out because I have very small part of the electric fence covered with that type of tubing you can slip around the wire. It was shorting through a staple and the staple was shorting on a metal bracket.
We’ve had a couple birds die from the electric fence and have shorted it out.
Once a small tree was blowing into the fence. So far, every time something has shorted the fence out, it has made a pretty loud popping sound, so it’s been easy to find. But I only have 18 acres fenced, so it’s been pretty easy to find a short. I imagine with miles of fencing, sections with switches would be critical.
I like the idea of the AM radio. My wife bought a cheap one to find a break in the wire for a robot mower.
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Don’t know how well it works, I only have about 600’ of electric fence. I got the Zareba FD1 for Christmas a few years back. If there’s a short it’s supposed to be able to point in the direction of. Potentially quite handy for a large fenced area, if there aren’t isolated sections.
Some good ideas here.
If the Al frame is not grounded then the high voltage must be coming in on one of the PV leads or it is induced to the frame. I’d be surprised if a simple rectangular frame could induce enough voltage for you to feel it, so I suspect backfeeding from the charger; but who knows. You could disconnect the - and + PV leads and see if either or both being disconnected make a diff. And disconnecting the coil of wire to see if it is inducing voltage anywhere is a good idea too. In short (no pun intended), just keep disconnecting things until the charge on the frame goes away, then you can work your way back once you know where it is coming from.
Having a cheap fence tester would be handy (they aren’t too expensive and a lot safer and more comfortable than using yourself to test for voltage, especially on a 120vac charger). If you can get your hands on one, you might try seeing if the batt terminals and the CC terminals show any high voltage, I would think they would.
Just curious, does the charger say that they expect batt - to be physically grounded? If so, maybe they are aware of the hi V leakage and want to control it that way.
I can’t say offhand if high voltage in the CC or batt would be a problem, can’t imagine it would be good for them. But it may be at such a low current that it does no harm. If it does turn out to be coming from the charger internals, you might want to contact the company and complain; sounds like a potentially dangerous situation if they are back feeding high voltage pulses on the 12v lines.
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A local method to test a fence,… say if you are out hiking and come across a fence and want to know if it’s hot ,/ , or not .
Is to grab a nice green leaf of tall fescue ,around a foot long ,
Hold the base of it with Bare fingers, touch the tip of leaf to fence wire , and slowly shorten the distance . If you can get within a inch or so and feel no pulse, likely the fence is off. .?
Licking your fingers and repeat will tell for sure.
Usually ! ?
That’s a Wv. Fence tester !
Cheep , easy to access.always handy.
Blinking lights on a scale … , fence tester ,much more info about what’s really going on …safer , not as stimulating ? But peace of mind …
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So this is where I’m at now.
Today I disconnected the hot fence wire from the fence charger.
Here are a couple pics to make sure it’s clear.
So I touched the PV frame with the charger hooked up to the fence and touched the PV frame without the charger hooked up to the fence. I tested this like 3X to make sure I got a consistent result.
There was definitely more shock on the PV frame when the fence charger was hooked up (by hooked up, see photos above).
However, there was still some shock on the PV frame, even when the fence charger was not hooked up, so I suspect backfeeding from the charger itself.
I did not disconnect the leads of the PV panel itself. I’ll do that next and see what happens. That’s a good idea.
For sure that’s a farmer’s trick. I’ve used that before, as mentioned earlier, but not before being dared by one of my employees to grab the fence, ugh.
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I grounded to the top wire of my electric fence (the top wire is a negative line connected to the metal T-Post with a metal clip).
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Another thought: IIRC you’ve got a lightning arrestor in the ground and hot lines to the fence. Basically just a coil. That coil could in theory be keeping some of the high V pulses in the charger side, same way it keeps lighning out. Simple way to test this theory would be to clip a test lead around the coil (eg bypassing it) and see if the charge on the frame and elsewhere goes away.
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I’m not sure I understand you Steve. The lightning arrestor is on the hot wire side of the fence. That is if by lightning arrestor, you mean the little gizmo with the small galvanized coil of wire, like this:
The hot fence wire comes from the hot side of the charger, then goes through a big coil of insulated galvanized wire, then goes to the top knife switch, then goes to the gizmo with the small coil of naked galvanized wire (lightning choke/diverter) then finally attaches to the hot wire on the fence.
The ground side of the fence comes from the ground side of the charger, then to the bottom knife switch, then finally to the field fence.
I did test the frame of the PV again. This time with the PV unplugged, but with the charger on. I could not detect any pulse current at all on the PV frame with it unplugged. So apparently all the backfeeding is coming from inside the charger itself.
I had thought I could detect a difference when I unhooked the hot fence wire from the charger (see post above) but I must have been imagining a difference.
All this stray current on the PV frame must be coming from inside the charger. This also tells me somewhere one of the PV wires is connected to the PV frame.
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Sounds like your saying bypass the arrestor since its not neccesary to eliminate it as a possible source of the problem. In terms of repair i look at it like that same way as car electric issues. Electric issues are some of the worst but overtime i learned to start at the point of problems and work my back eliminating problems as i went back. Any point is where you start and find another point. As an example lets say left rear turnlight is out. Check the fuses first replacing with known good fuses. If its not a fuse check signal light bulb second replacing with a known good bulb. If its not the bulb or fuse it is the wire in between. We are assuming you have determined Its not the flasher because flashers do not cause the light to go out rather they make it flash and the noise indicates flasher is ok. In the case of a highly complex system one trick might be before yanking out old electric wire we run a new electric wire temporarily outside the car to ensure that would fix the issue. Then we consider removing items to get to the old wire. Get a system back to its simplest form before adding back the complicated parts of it. That arrestor is not neccesary its a precaution so eliminate it temporarily. Technology is far more advanced than what im saying im simplifying things to be explained easier. In the real world if im tracing a network cable break i do so with a tdr StackPath . There are cases im told where a thumper is used for tracing but throughout my career none was necessary
Back to your fencer @Olpea i would do as @Steve333 is impliying and use process of elimination bypassing devices such as that until you find the right one. Its not an elegant solution but we know we use it frequently with many things on the farm. If your working on an egine you test if the engine has fuel and if it does we check for power to the engine. All of us who live on a farm were taught the fuel and fire method when we were children. If you were riding a 4 wheeler and it died there are no mechanics out here that work on 4 wheelers. So you better figure out how to make it run or get used to walking. Same way now there are precious few solar guys and they dont work cheap.
Thanks Clark.
Actually I think I’ve done what you suggest, unless I’m missing something. Since I completely unhooked the hot fence wire right at the charger, in my mind it eliminates anything down stream from the fence charger causing the pulse on the PV frame. That would include my “homemade” lightning choke and the store bought fancy gizmo one (shown in the pic above).
They wouldn’t be causing the pulse on the PV frame since they are down stream of the point which I disconnected the hot fence wire. That’s why I thought it has to be backfeeding from the inside the charger itself. The only thing which shuts off the electrical pulse on the PV frame is by disconnecting the + and - wires on the PV.
I suppose it would be the equivalent of trying to diagnose a ground fault which causes a fuse to consistently blow on a car. If one disconnects the wiring harness at one point, and the fuse still blows, anything downstream of the disconnect point is eliminated from causing the problem (since it’s disconnected).
Unless I’m missing something, I think that’s where I’m at now. If the charger, charge controller and the solar panel are the only things hooked up, and I still get the pulse on the PV frame, then it has to be one of the three. I don’t see how it could be the solar panel or the charge controller because they shouldn’t “pulse” the PV frame with current. By the process of elimination, that should leave the fence charger as the only cause of the problem (since it’s the only thing of the three which pulses). That is, again unless I"m missing something, which is always possible in diagnosing electrical problems.
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Thats what i would do as well. Sounds like your almost there. @Steve333 was saying use process of elimination i think unless i misunderstood. Sounds like everyone thinks about the same thing at this point.
Interesting.
I was thinking that the lightning arrestor/choke might be working to limit some of the voltage getting out of the fence charger and that was causing feedback thru the rest of the system. I didn’t remember your exact setup, and thought you might have one of those lightning chokes on both ground and hot fence lines, but either might cause this. Might be nothing but would be interesting (to me at least 
) to check, and pretty easy, no rewiring just attach a jumper across that coil temporarily, and see if it changes the charge on the PV frame when its connected.
Yes, sounds like one of the PV leads is connected to the frame. Might want to pull out the ohm meter and check resistance of each to the frame to see which one(s) it is. Might be a high resistance connection as opposed to a dead short.
I’d agree, seems like the voltage is from the charger itself back feeding thru the rest of the system. Might be of interest/use to figure out which of the PV leads is the pathway, +, -, or both. Just connect them one at a time and test.
Might also be helpful to contact the fence charger manufacture and see what they say about the problem. This could be something they are aware of or have dealt with before.
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