Failure Mode of Charge Controllers (Xantrex MPPT60-150)

a1certifieda1certified Registered Users Posts: 34 ✭✭

I have an inherited Xantrex grid-tied, battery backed system in a house I purchased. I've been debugging it over the last week and have got most things figured out.

In the process of debugging, I discovered that I had a failed Xantrex MPPT60-150 charge controller. The system has two strings of panels on the roof, each going to a separate MPPT60 and then both of those going to a common battery bank. One charge controller consistently generated power and the other one consistently did not. The readings I saw on the charge controllers: working one with nominal voltages of 75-95V and amperage commensurate with the amount of sun; non-working one with nominal voltages of 75-95 but amperages next to zero (it would read about 3W). I made the assumption that there was something going on up on the roof with the panel wiring as that is the most exposed component in the system.

But to be sure, I thought I'd switch the positions of the charge controllers relative to the strings of panels. Did that this morning before the sun came up. So now I had the charge controller that was working on the string that wasn't putting out any power previously. Lo and behold, when I fired things back up and the sun came out, the previously powerless string was now putting out nominal power. And the string that was putting out power previously was now not putting out any power. So the fault is clearly with the charge controller.

I can't say for sure, but I am assuming that it has never worked from the time I purchased the house. I would assume that it worked at some point in it's 10 year life with the previous owner, but again, impossible to say. I never checked the system in detail except to see that the blinky lights were blinking. My experience with the system on my primary house with a similar Outback system has been "set-it-and-forget-it". So I got lazy on checking this before plunking down the cash.

At this point, I know I have to get a new charge controller, but I'm curious, what is the typical failure mode of a charge controller like this one? An overcurrent problem? A temperature problem? Old age?

Comments

  • EstragonEstragon Registered Users Posts: 3,856 ✭✭✭✭✭

    My first guess would be failed FET / power board. I imagine there are some diagnostics you could do to narrow it down though.

    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • a1certifieda1certified Registered Users Posts: 34 ✭✭

    Are those field replaceable?

  • EstragonEstragon Registered Users Posts: 3,856 ✭✭✭✭✭

    I did it on my Outback inverter and it was pretty straightforward, but don't know about Schneider gear.

    In any case, you'd want to establish whether that's even the problem. It's mostly a WAG on my part. The FETs get hot, and heat makes electronics sad.

    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • a1certifieda1certified Registered Users Posts: 34 ✭✭

    I ended up purchasing a new MPPT60 and when I plugged it in - voila - full power. I'd like to troubleshoot the defective unit at some point and keep it as a backup for future possible needs. Is there a service manual available for these?

  • mcgivormcgivor Solar Expert Posts: 3,028 ✭✭✭✭✭
    edited May 7 #6
    The one thing I would check is the ground fault fuse, if installed, it's a 1A fuse inside the wiring compartment if blown it would cripple the unit.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • a1certifieda1certified Registered Users Posts: 34 ✭✭
    If I recall correctly, if there are two MPPT60's only one is supposed to have the fuse installed?  I believe this one did not have it installed.  It was empty.
  • mcgivormcgivor Solar Expert Posts: 3,028 ✭✭✭✭✭
    You are correct only one should have a fuse. Have you tried disabling the controller in the device menu, there should be a click when doing so from the relay.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • a1certifieda1certified Registered Users Posts: 34 ✭✭
    The "bad" controller is currently sitting on a shelf at the house and I'm 1600 miles away!  :-)

    I can try that next time I'm at the house and see if there is a click.  That should be sometime in July.  What am I troubleshooting with this maneuver?   If there is a click from the relay then it means ...?  If there is not a click from the relay then it means ...?  I'm just trying to understand the troubleshooting process.  Thank you so much.  Please keep the troubleshooting recommendations coming.

    Turns out there was a lightning strike in the area last night and that took out my grid AC.  House properly switch to inverting from the batteries (and are still inverting).  Voltage went from about 51V to 49.9V before the sun is starting to peek out now and recharge the batteries.  Gratifying to know that all this time and money is resulting in the intended behavior from the system.


  • mcgivormcgivor Solar Expert Posts: 3,028 ✭✭✭✭✭
    The click will confirm the relay is operating, it may be the the controller was disabled perhaps unintentionally, just using a pragmatical approach rather than jumping to conclusions. Then again 10 years is in.the ballpark of life expectancy for most electronic devices, depending on environmental conditions, without a fan moving air over my MPPT 60 150, temperatures rise to 60-70°C, with a fan it maintains close to ambient, which itself is often 40°C.. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • a1certifieda1certified Registered Users Posts: 34 ✭✭
    I went through the basics of rebooting, resetting, reprograming, etc. of the charge controller before finally deciding that it was just "dead".  So I think that there is something internally wrong with it.  Simple setting changes never brought it online.
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