locating controller and battery monitor

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landyacht.318
landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
I am designing the cabinet into which I plan to place my Bluesky2512i controller and IPN pro remote battery monitor and many other electronics. The directions say to run the shunt wires away from the power lines. Does this mean I should try to keep the controller and monitor widely seperated?
I would like to mount them fairly close to each other.

Another question I have concerns the shunt wires. The instructions say they must be twisted pairs, and that lengths over 35 feet should be shielded twisted pair cable. My shunt wires will be about 6 feet long max, depending on the response here to my first question. Would I benefit from buying some twisted pair shielded cable, or could I get away with twisting up my own pairs of 16awg wire?

Could I shield the wires inside some Aluminum tape and ground one side?
How many twists per foot?

I realize my controller will disrupt my AM radio reception, but how about FM and Analog TV reception?

I'd like to eliminate any problems in this design phase than chase them down after things are glued and screwed, soldered and hidden. The system is to be wired into a class b motorhome. Any advise on heading off electronic noise greatly appreciated.

Thanks

Geoff

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Shunt wires can pick up radio noise pretty easily and interfere with accurate voltage measurements back at the controller...

    Twist the wires about 4-6 turns per foot should be more than enough (the tighter the twist, the higher frequencies rejected). Take you length of wires and chuck one end in an electric drill for a quick twist.

    If you have a "noise" environment, running shielded cable (ground the shield jacket at at least one end to a "quiet ground")--such as AC inverters, or other large switching loads, etc. nearby, then shielding is not a bad idea.

    Don't bundle tie the shunt wires with your DC power cables or AC mains in long parallel runs. As long as you are more than an inch or more away from parallel runs--you should be OK. If you need to cross a run, do it at 90 degrees (right angle).

    Keep the solar panel to battery harness, and the charge controller itself, at least a few feet away from any receivers--but you may still have problems (which maybe difficult to solve as the problem is usually with the charge controller's design being electrically noisy). One person here solved the problem by just putting a switch in the solar panel wire and turned it off when they wanted to listen to the radio.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
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    Hi, I made up my own twisted cable for my XBM of approximately 5 meters using two cores from some six core burglar alarm cable. I also used a battery drill to obtain a good tight twist of 30 per foot. But initially having the problem of it wanting to untwist its self and coil up on its self. I cured this by cutting small one inch pieces of suitably sized heat shrink on to the twisted wire whilst still under drill twisted tension and using a heat gun shrunk the heatshrink every 4 or 5 inches apart. The heat shirnk stops the untwisting and the heat gun helped form the two wires to avoid coiling when the tension was released. The tighter twisted pair helps avoid erratic readings I run mine through the same 4 inch conduit as my gen to inverter cable with no ill effects. You could even use the discarded alarm cable outer covering for further shielding. Hope this helps Nigel
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    i have not had any problems with interference anywhere with my sb50dl even having the meter physically out, but still connected for adjusting my voltage setpoints. i hear nearly all aspects of the radio spectrum being a ham radio operator and i don't hear anything from my controller so you should be fine twisting up some of your own wire for yours. this minimizes interference out of and into the controller/meter. there are circumstances that may warrant the extra efforts of shielding, but i don't believe that may apply to you. if you see meter readings wandering this may be interference being picked via the wire and then may warrant the extra efforts beyond twisted pair.
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Thanks for all the info.
    I'm going to mount the controller and monitor about 6 inches from each other and run the output leads (twisted)on opposite sides of the cabinet. I'm probably gonna twist all my other power leads as well. Inverter, fridge, and everything inside the cabinet.
    The network/power cable(phone jack wire) that connects my controller and monitor. They seem to have given me 20 or more feet of it. Will leaving it all coiled up inbetween the 2 devices do something more than being aesthetically unpleasing?
    If I were to buy a shorter length of network/power cable, would the new cables swap pin numbers like the supplied one? Is this standard with all phone 4 pin telephone cable?

    The charge controller came with the metal electrical box. I've already run a 12 foot, 12 gauge 3 wire tinned copper flat marine cable from the roof to the general area of the controller. I was planning on grounding the frame of the panel to the box with the 3rd wire, then grounding the box to the frame. Will this be adequate? Does the monitor need to be ventillated? It came with no box and I wanted to protect the back end with a hardwood box. But maybee I should mount it inside a grounded metal electrical box as well?

    Thanks again for all the info.
    Geoff
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    that is quite an excess of cable and that excess can increase the chances of interference. you might do well to get a shorter cable with the proper connectors, but do hang onto the long one for possible problems you may have as wires can fail or if you have future need of a longer remote view.
    as to the grounding i am not one to advise bringing the pv ground down into the house from the pvs to the controller as this invites lightning into a home. both pv and controller do need to be grounded outside to a ground rod. just do not run it in series as a ground wire should run from both the pv and controller to the rod, but seperately. we've had lengthy discussions on this and i recommend you read up on this.
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: locating controller and battery monitor

    Neil,

    I appreciate the info. As to the grounding, I did a search and was not able to find out much info for grounding the Panels in an RV application. If It were to be mounted on a house I certainly wouldn't bring the panel ground wire inside. With an RV that has no earth ground, I'm not sure what would be best in terms of a lightning strike. I figure if the rv gets hit, the lightning is coming in no matter what, But then I'm hardly an expert. Most of the time I will not be located in areas prone to lightning. But currently I'm in florida, and my ears are still ringing from a very close strike yesterday.

    By the way, does the battery monitor need ventilation? I'm going to need to protect the back side of it where i plan to mount it, and am wondering if I should aquire another metal electrical box like what came with the sb2512i. Can I get away with making a box out of some teak or oak I've got lying around?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: locating controller and battery monitor

    if the trailer is parked for a long term, please do put in a ground rod. for those on the go as rvs are designed to do then there's little you could do for a good earth ground, but a poor one may suffice as it may be better than nothing. by this i mean even a small piece of copper pipe driven 1/2ft into the ground with at least a good flexible(stranded to help stop breakage) #10 kept as short as possible with no sharp bends and coming from your electrical box ground. 1ft copper pipe into the ground would be better than a rod than 1/2ft in, but this is more difficult to pull up anchor so to speak. most in your circumstance do not earth ground at all and that'll be your choice. remember, there are no guarrantees when it comes to lightning no matter the precautions taken.
    meters would probably be less prone to interference or damage with a metal enclosure, but there's nothing wrong with putting wood around it for aethetic reasons. i am not familiar with that meter to know if they require venting. if you find nothing from them about it then you can judge by seeing if you feel any heat from it after putting it say under a pillow for a few minutes. measuring the temperature would be a better indicator than touch btw.