Charge controller buzzing

Lifetide
Lifetide Registered Users Posts: 19 ✭
in Off Grid Solar & Battery Systems #1
I have a Xantrex C-35 charge controller with max 28 to 30 amps coming in to the system from my solar array. I also have a fused disconnect switch that has a a 60 amp ammeter and a voltmeter wired to it. I recently noticed that there is a faint buzz coming from both the ammeter and the charge controller.

One of the 30 amp buss fuses is also fairly hot. I've checked all the connections for loose wiring, but everything seems okay. The buzzing only happens when the incoming current is about 20 amps or higher.

The 30 amp ammeter had the loudest buzz, so I suspected it. I bought a new 60 amp ammeter and installed it, but the buzz is still there.

I have another smaller array with the same setup, so I put my ear to the ammeter and charge controller on that system; and sure enough, there was a very faint buzz (and also a warm fuse). It could be that the buzzes have been happening for years and I just never noticed them because they are so faint.

Can anyone tell me if this buzzing is normal.

Thanks in advance.:confused:
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Comments

  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #2
    Re: Charge controller buzzing

    I had a C60 and a C35 at one time and I would hear that same noise as well so I guess it is normal. And I am pretty sure they also cause RF noise in other devices.

    However, the wires being "hot" are a concern. "Warm" may be ok, but "hot" might mean the wire is undersized.
    I always overkill on wire just to be safe (from fire and voltage drop). I would use at LEAST a #8 on a C35 or a #6 of you have any kind of distance.

    Also, I was at a friends last week and noticed that one of the wires, a #4 from his C60 was super hot. I mean you could not hold on to it with your fingers. Although the wire size was ok for his load (50amps) it looked like at one time one of the connections had been loose and caused excessive heat which in turned caused it to loosen more, and so on.

    Investigation showed that it has melted almost all of the insulation off the wire all the way from where it terminated on the controller lug to the point where it exited thru the strain relief on the controller housing and the once bright colored copper wire was now almost black. So even with an over-sized wire, loose connections can be a serious issue.

    I would check all of the connections and if the wire is discolored, that might be a sign that it has been/is loose. Don't try to clean that end of the wire, cut it off and start with a clean section. If the wire is too short to cut off, replace that section. And in about a week go back and retighten all of your connections.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: Charge controller buzzing

    Probably perfectly normal. Most charge controllers rapidly pulse current through the cables etc and this in turn results in pulsing magnetic fields that attract and repulse, causing things to vibrate/buzz/hum.
    My Morningstar TS-MPPT_60 has a high pitch hum when charging heavily. Have no idea where the vibration is originating, but the frequency matches the mechanical resonance of some of the cooling fins. Just touching the fins stops the hum.
    PS: I was referring to the buzzing when I said probably perfectly normal.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Charge controller buzzing

    if one fuse is hot and one fuse is only warm then there could be a bad fuse with the one getting hot. one might expect them to get a tad warm as they are a small point of resistance. don't run out and buy one, but rather put the warm fuse into the slot of the hot fuse and see if it just stays warm or if it then gets hot. if it gets hot then suspect wiring or even the fuse holder itself.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: Charge controller buzzing

    As Niel says--Check the fuse holder and wiring--They frequently get a light corrosion over time and need to be cleaned up. Otherwise, the holders/connections can overheat.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #6
    Re: Charge controller buzzing
    BB. wrote: »
    As Niel says--Check the fuse holder and wiring--They frequently get a light corrosion over time and need to be cleaned up. Otherwise, the holders/connections can overheat.

    -Bill

    Have seen this a number of times over the years in different applications. Sometimes the fuse will get so hot it will go open from the heat, not from over current.
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