setting for MX-60

Brock
Brock Solar Expert Posts: 639 ✭✭✭✭
My MX-60 used to have 4 KC120's in series / parallel so about 32v in and feeding the 24kw 12v bank. Now that I have moved and rewired everything I have a new configuration. 8 KC120's wired in series parallel for 63v feeding the 24kw bank now setup for 48v.

I am concerned I tweaked the setting when I had the MX-60 in the 24/12 setting with the lower amperages and now that I am at about 64v at 12a on the input side and 52v at 14a on the output side. I went through the manual, but again most of it went over my head as far as tweaking it and don’t even know what the system defaults are or should be.

I don't have any issues with how it is working, everything seems fine, but if I can get a couple more watt's out of the system that would be great.

Is there a way to reset the MX-60? Or should I just change some of the setting manually, like park and sweep interval and all that good stuff?
3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI

Comments

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: setting for MX-60

    Brock,

    You can go through the power up sequence to reset the MX60 to its factory defaults for whatever system voltage you choose. The controller should have reset when you switched from 12 V to 48 V.

    I use the East Penn / MK charging instructions, normalized for 77 F, for the settings for my AGM batteries. For your application, I would recommend initial settings of 57.4 V absorb, 2-1/2 hrs. absorb time, and 53.4 V float. See: http://www.mkbattery.com/images/AGMBatteryCharging.pdf

    My recollection is that the KC-120’s STC Vmp is 16.9 V. You may therefore find charging a 48 V battery bank from a “48 V” array to be a challenge, especially in the summer time when the array is hot and the MPPT voltage is low.

    You may find that converting from 12 V to 48 V results in some extended and annoying relay clicking as the MX60 goes through its morning waking routine. See this post on the OutBack forum if you have the latest MX60 firmware (5.10 or 5.11): http://www.outbackpower.com/forum/viewtopic.php?f=29&t=2834

    Don't forget to calibrate the MX60's voltmeter. There are few other tweaks that might be of interest, but he above list is a good place to start.

    HTH,
    Jim / crewzer
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: setting for MX-60

    Ok, I think it did do something different when I turned it on the first time at this new house. So hopefully it did reset (although it remembered the log settings as if this was just a new day). I just remember you suggesting me tweaking the park % and didn't know if that reset or not.

    Yup I have voltage and absorb set to what you suggested, so I got that right anyway. And yes I did adjust the voltage (it was .2 high)

    The lowest voltage I have seen was actually today at 60v with it being 92F outside with full sun, but the bank was at 54 with the inverter running so it was fine. I run off solar and batteries during the day during high peak rates from 9 am to 7 pm, so the battery voltage is usually lower then absorb. I have been in the 95% to 100% when we hit off peak and go back to the grid at 7pm
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: setting for MX-60

    Brock,

    Yeah... I forgot about the Park % tweak... The issue is trying to deliver maximum bulk-stage charge current when the controller output is <5 A. I ended up using 85% for my old MX60 rather than the default 77%... you may need to experiment a bit... I suspect the you'll find the "sweet spot" between 80% and 85%.

    Best of luck to you!
    Jim / crewzer
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
    Re: setting for MX-60

    It makes sense that at less than 5 Amps the park % would be higher than 77% because low current usually happens when there is less sun-icity (my new word for the day). At lower irradiance levels, the MPPV percentage of Voc is higher than the usual 75% range that you see in the middle of the day.

    boB :D
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: setting for MX-60

    OK now you guys are confusing me (which is good).

    What exactly is that park % (I am assuming it is the ration from incoming voltage to outgoing voltage?) and does it only look at that in U Pick? Or does it affect it at other times as well? I am actually more concerned about peak output during full sun, in the 15 amp at 62 volts on the input side and 17 or 18 amps at 52 volts on the output side.

    Or should I just let it do its thing. I did get the firmware updated about 14 months ago.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
    Re: setting for MX-60

    Ahhh... OK Brock.
    Park % is used in regular auto mode, but only if less than 5 Amps output. It won't be used in full sun like you're talking about. Park % is only used all the time in U-pick mode. The park % sets the PV voltage in those certain modes. If the PVs Voc was 100 Volts, at park 77%, the PV voltage would be parked at 77 Volts during those times.

    Full sun does not normally use that %. U-pick mode was put in the MX60 mainly as an extra mode to play with, and not really a substitute for auto tracking the max power point. It was also put in there to compare what another charge controller uses for their tracking, except it used a fixed voltage "offset" from Voc rather than a percentage. That "offset" method was patented around 2000, but the percentage of Voc (which is ~really~ the same kind of thing), was written about in engineering articles in the early 1980's. There was a reference to one of those articles in the old MX60 manual.

    The park % works kind of so-so but is a lot of times pretty darn close.

    boB :D
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: setting for MX-60

    Brock,

    The MX60 uses the Park Mpp% to hard set an array's operational voltage when the controller is set to Upick% mode (Advanced menu, MPPT Mode). As boB indicated, if the Park Mpp% is set at 77% (default) and the array's Voc is 100 V, then the controller will set the array's operational voltage at 77 V, and the periodic sweep function is disabled.

    Assuming you're running your MX60 in "Auto Sweep" mode (Advanced menu, MPPT Mode), then your controller will use the Park Mpp% value to set the PV array's operational voltage when the controller's output current is <5 A and when operating in Bulk-MPPT mode. Periodic mini-sweeps will continue, and, once controller output current exceeds 5 A, then the controller will set the array voltage at the actual MPP.

    I found a few years ago that 85% was a better Park MPP% value than the default 77%. Here's a link to one of my early discussions with dear ol' boB: http://www.outbackpower.com/forum/viewtopic.php?f=9&t=515&hilit=85

    HTH,
    Jim / crewzer
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: setting for MX-60

    Ahhhh, now I get it. So it only really comes in to play if your under 5 amps or you set it to the "u pick" mode, which mine isn't.

    Ohhhh button 3 and 4 move the point up and down, something more to play with :)

    Ok I think I am set then. Now to upgrade my #4 from the roof down, I should have kept that old 00/ feeder I had before we moved.

    Bob you have to build a version that takes higher input voltages to save us all a bunch of wire ;)
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
    Re: setting for MX-60
    Brock wrote: »
    Bob you have to build a version that takes higher input voltages to save us all a bunch of wire ;)

    Working on that...
    I'm not positive, but I think that the MF80/MF60 doesn't let you raise and lower the PV Voltage with buttons 3 and 4 ?? Does it, Jim ?

    And I believe they removed the Amp-hours/kWh-Hours selection with button 2 ?? Is that correct ?

    boB :D
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: setting for MX-60
    I'm not positive, but I think that the MF80/MF60 doesn't let you raise and lower the PV Voltage with buttons 3 and 4 ?? Does it, Jim ?

    And I believe they removed the Amp-hours/kWh-Hours selection with button 2 ?? Is that correct ?
    boB,

    As best I know, the MX60's voltage tweaking feature using buttons 3 & 4 was not carried over to the new FM60 and FM80 controllers.

    The MX60's button 2 toggle for Ah / kWh display on the status and data logging screens was changed for the FM controllers. Button 2 now calls up the "End of Day" summary screen that displays both Ah and kWh data. Please see the attached pic.

    HTH,
    Jim / crewzer