XW-MPPT60 Config

TheBackRoads
TheBackRoads Solar Expert Posts: 274 ✭✭
in Advanced Solar Electric Technical Forum #1
Hey all,

I have a question about programming my XW charge controller. I'm looking at having the aux connection turn on and off a relay to loads. Maybe some of you can shed some light to see if this will work. I know there is not a "At float, turn aux on" so we have to do this by voltage.

Current set points for batteries:
Bulk 14.5
Absorb 14.7
Float 13.8

Now my question is if I set trigger for 14.7 at the end of the absorb charge it should trigger the load (before it hits float), and then clear could be set to like 13V or something. If I set it for like 13.8V trigger than it would come on before the batteries are charged I'm guessing. Does that sound like it should work?

Jeff P
AKA TBR ;)
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #2
    Re: XW-MPPT60 Config

    Hi BR,

    Well, it IS too bad that X/S could not figure out how to make Aux active on Float function work, but they could not.

    In looking at the downloaded manual that I have, I cannot see how to make the Aux Output function the way you want it to, without an external timer or something like that.

    The prob is that when the CC reaches the Asorb target voltage, it tries very hard to maintain that voltage -- the Asorb voltage should not change during the Asorb stage. So setting the triger to the Asorb V turns on your diversion load, which would reduce the power available to maintain Asorb, so you would loose ground on charging the batts. If you could set a delay of 1/2 or 3/4 of the Asorb stage time, and then activate the the diversion load, you could be OK, BUT, the Asorb time is usually a variable amount of time.

    It does astonish me that X could not figure out how to code the Aux on Float function. How many lines of code could it require, and how many lines of description in a manual would it take ? Altho, My POS XW CC did not even know what charge stage it was in ... It would proudly state it was in Asorb, when it was really still in Bulk -- HOURS away from Asorb.

    I believe that if you set the trigger for the float voltage, then you would begin diversion during Bulk, when it passes through the Float voltage.

    Someone here, did state, prehaps one year ago, that they were able to simulate Aux on Float function by with settings of battery voltage, but I cannot see how this would work.

    It might be possible to use PV in voltage, with some delay for the trigger, and harvest some XS PV power. This is not perfect, but might be worth a look. I only ran my XW SCC for a few days, before throwing it in the pond, so do not recall just how it tracks MPPT. Think it is rumored to use Petrub and Observe, rather than Sweeps for MPPT Tracking, so the reqd trig delay may not be very long.

    Some of the XW hotshots should chime in about now, and tell us all what I am missing.

    A request to S/X for the Aux on Float function might not hurt.

    Too bad the XW SCC missed the boat on this IMPORTANT Off-Grid CC function

    Just MHO, YMMV GL, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #3
    Re: XW-MPPT60 Config

    Vic is right, you are going to need a timer to enable the aux function relay. I am doing what you want to do on my 24 volt system. But I had to do some tricky programming to get it to work correctly. My dump load is a 1KW water heater. I know that it takes me a good four hours to make 120 degree water. So ideally you want to create a "window" of time when the dump load can operate.

    Now here is the tricky part. Since X does not have the aux on float option, you can only do it with voltage. So you need to program the SCC to be in 3 stage mode, then you set the float voltage equal to the absorb. Yep, that is right, float equal to absorb! Then you set the aux voltage trip point to this "higher" float voltage. What happens is that when the controller goes into float mode, it always overshoots slightly. This overshoot can be used to trigger the dump load. So now you have essentially tricked it into activating the dump load only when the timer says its OK AND the controller reaches float.

    So how do you deal with the fact that you can cook your batteries? Well think about it, when the dump load turns on, the battery bank voltage will begin to drop. The trick is to use the setpoints for the kick in and kick out to keep the battery bank voltage at your DESIRED float voltage.

    I admit this is a kind of Rube Goldberg way to do it but my system works quite well. The only caveats are that as the sun angle changes throughout the seasons, you have to adjust the timer to keep the dump load window properly timed so you dont overcharge the batteries. I use an X-10 dawn / dusk timer so its kind of automatic for me.

    Fortunately, I have trojan FLA's so they tolerate this pretty well, they dont seem to mind it and IMHO, keeps the bank charged to a higher level. I dont see this in my battery monitor per se but I do see a big improvement in maintaining the SG.

    In any case, my system is 24 volts so I have the SCC programmed as follows:

    Bulk = 29.7
    Abs = 29.6 (so it is boost charging)
    Float = 29.6

    Aux = auto
    Trig = Hi battery V
    trigger level 29.6V
    trigger delay = 30S
    release level = 26.4 (my desired float voltage)
    release delay = 15S

    So to recap, the timer ensures that the aux function is locked out through the bulk and absorb stages. When the timer enables, if the batteries are well into absorb, the dump load will come on and pull the battery bank voltage down to something close to 26.4 volts. This will put the SCC back into absorb mode and may or may not bounce between absorb and float mode depending on how much energy you are harvesting. The relay will cycle as necessary if clouds go by or whatnot to ensure that the bank does not go out of the range of 29.5 and 26.4 volts. You should also program the timer to disable the dump load a couple of hours before the sun sets to give a final top off to the battery bank for the night.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #4
    Re: XW-MPPT60 Config

    Joe !!

    Thanks for the detailed info. Ideally, a mcirocontroller which monitored the batt voltage, and perhaps PV in voltage, one could emulate this function fairly well.

    Still oo bad for you XW full-system folks that it is not where it belongs. For me going to a REAL Off-Grid CC was the solution,

    Thanks again, Joe. X/S can be a bit frustrating to deal with, altho, my SW+ 5548 inverters have been very solid .. knock, knock.
    Good Luck, BR. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #5
    Re: XW-MPPT60 Config
    Vic wrote: »
    Joe !!

    Thanks for the detailed info. Ideally, a mcirocontroller which monitored the batt voltage, and perhaps PV in voltage, one could emulate this function fairly well.

    Still oo bad for you XW full-system folks that it is not where it belongs. For me going to a REAL Off-Grid CC was the solution,

    Thanks again, Joe. X/S can be a bit frustrating to deal with, altho, my SW+ 5548 inverters have been very solid .. knock, knock.
    Good Luck, BR. Vic

    Actually, there is a way to tell exactly when the system goes into float mode. The XW AGS has a function that will stop the generator when the batteries actually reach float. So if you want to blow some cash on that AGS, you can use the stop relay to control the dump load relay. I have tried it and it does work however, I use my AGS with my EU5000I so I cant use the stop relay to do this for me.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #6
    Re: XW-MPPT60 Config

    hi JoeB,

    Can the XW AGS plug into the XW SCC? I have NO other XW hardware than the SCC. AND, I would still need to jump through the hoops to update the SCC FW.

    Thanks, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #7
    Re: XW-MPPT60 Config
    Joe_B wrote: »
    When the timer enables, if the batteries are well into absorb, the dump load will come on and pull the battery bank voltage down to something close to 26.4 volts. This will put the SCC back into absorb mode and may or may not bounce between absorb and float mode depending on how much energy you are harvesting. The relay will cycle as necessary if clouds go by or whatnot to ensure that the bank does not go out of the range of 29.5 and 26.4 volts. You should also program the timer to disable the dump load a couple of hours before the sun sets to give a final top off to the battery bank for the night.

    When your dump load is on, and your bank gets to 26.4V doesnt that already trigger your CC to bulk since that setpoint is 29.7 in your case? And when you mean "Timer" are you talking about the built in one on the XW?

    PS -- Thanks for that info!

    J
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #8
    Re: XW-MPPT60 Config
    Vic wrote: »
    hi JoeB,

    Can the XW AGS plug into the XW SCC? I have NO other XW hardware than the SCC. AND, I would still need to jump through the hoops to update the SCC FW.

    Thanks, Vic

    Well all the XW stuff utilizes the xanbus so yes they can be networked. You will also need an SCP to program stuff. The only thing I dont know is what source the AGS uses to determine when float is achieved. I have the XW4024 as well so it works for me. I do know that the chargers do share information of states so maybe the AGS does as well. Just dont know the answer to that one.
    TheBackRoads wrote: »
    When your dump load is on, and your bank gets to 26.4V doesnt that already trigger your CC to bulk since that setpoint is 29.7 in your case? And when you mean "Timer" are you talking about the built in one on the XW?

    PS -- Thanks for that info!

    J

    The timer I am refering to is an external device. It essentially enables the relay driver so the aux can control it. I originally had one of those cheap intermatic ones that I placed in series with the aux output. I have since hooked it up to my X-10 system so it follows the dawn / dusk times. I program it for on at a certain time and off at 2 hours before dusk. it works pretty well.

    So with the timer, the bulk and absorb states proceed normally and then when the timer allows it, the aux will turn on the dump load. You just have to make sure that you allow the dump load to turn on only after the batteries have had time to get through the absorb state. This is the Rube Goldberg part, you just have to monitor your system and determine a typical time during the day when you can be sure to b e through most of absorb. For me that is about 2:00 pm on a good day. So if we have clouds, the whenthe timer turns on at 2:00, the batteries will still be either in bulk or absorb but the bank voltage will be below the trip point so the relay will never turn on.

    If at 2:00 pm, the batteries are near the end of absorb, then the voltage will be high enough to turn on the dump load. Normally with my system, if we have good sun and I am cranking down nearly the maximum my panels can deliver, then with the load of my house in addition to the dump load power, my batteries will sit somewhere around 27 volts. 45 amps going into the dump load and 10 - 20 amps going into the inverter to run the AC loads. If a cloud happens by then the charge controller will not be able to supply enough current to the battery and the bank voltage will drop, when it drops below my lower set point, the dump relay will open and prevent the battery voltage from dropping below the setpoint. When the sun shines again, the bank voltage will then rise to my float voltage level and thenthe dump relay will again come on to keep the bank voltage around 27V, think of it as a shunt regulator.

    J
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #9
    Re: XW-MPPT60 Config

    Thanks for the info.. gives me a baseine to try out! Let me know everyone else if you have figured out this issue too! 8)
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #10
    Re: XW-MPPT60 Config

    It is just firmware to fix this! At least they are consistant and won't write some code. :cry: One can power the xanbus without an XWinv/chg. from the aux and then run the xw gen assy. You would need an external supply to run both the SCP and a xw gen assy. It sounds like too much work to me, I would just buy more solar so this is not an issue, if I had the money.....The xwcc definately has a the data that it is in float and displays it BTW.

    There is of course the most logical way to do what the OP wants here. You have to think outside the box. What would be better an even better use of unused energy than knowing you are in float? Why is float so desireable to force a trigger? What would even be better and XW chargers all do this?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #11
    Re: XW-MPPT60 Config
    TheBackRoads wrote: »
    When your dump load is on, and your bank gets to 26.4V doesnt that already trigger your CC to bulk since that setpoint is 29.7 in your case? And when you mean "Timer" are you talking about the built in one on the XW?

    PS -- Thanks for that info!

    J

    This would depend on where the xwcc's rebulk setting is programmed by the user!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #12
    Re: XW-MPPT60 Config

    There is of course the most logical way to do what the OP wants here. You have to think outside the box. What would be an even better way to use unused energy than knowing you are in float and starting at that time. Why is float so desireable to force a trigger? What would even be better and XW chargers and most others all do this?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #13
    Re: XW-MPPT60 Config

    *drum roll* -- starts thinking................... :confused:
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #14
    Re: XW-MPPT60 Config

    If you start a load based on the system being in float you are wasting quite a bit of unsed power. If there was a three hour absorb and an "average" level of discharge one could say that it would be better to start the load an hour or more before the system went to float.

    On small systems or in cloudy weather the following might not be acceptable. In systems that go to float at about the same time most of the year the Aux is used as a delay timer. The programming is basically the bulk/absorb setpoint and then a timed period of 2 hours in the above example. You would gain an extra hour a dayor more of running your load.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #15
    Re: XW-MPPT60 Config

    Yeah, I'm running some tests currently on voltage based on end of absorb voltage.:D
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #16
    Re: XW-MPPT60 Config

    DS, Yea, that was the TIMER that I was referring to.

    Almost all of the good MPPT CCs have Aux active on Float. But, as have noted before, one really wants Aux active on %of last Asorb time+Float or similar. Where one can set the approx point in Asorb where Aux becomes active.

    Perhaps even enough intelliigence where The %of Asorb time is attemped, and if the PV cannot support the additional load, the Aux becomes inactive for a period, and attempted again later. Two successive days of battery charge are not necessarily that similar, but a lot more could be done.

    Perhaps there should really a separate Power Skimmer controller, which knows the current state of the CC(s) and decides which additional load has priority etc.

    But, that the X SCC missed having even the most rudimentary Aux ative on Float function is a bit disappointing.

    And so on, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #17
    Re: XW-MPPT60 Config

    Well, here is my attempt to "automate" some loads (mostly networking stuff 50-60W 24/7)

    I followed 2ManyToyz directions and even supplier on eBay (Thanks 2ManyToyz!!). Relays were delivered today after quite a few weeks (apparently boats take awhile to get from china to NY). Full testing will begin this weekend, but as of now, I can turn on and off an AC load via the charge controller. However since I need items to be always running, I added a step. I purchased an APC ATS (automatic transfer switch. Model AP7750 on eBay) Below are some pictures. (sorry I didn't feel like cleaning)

    attachment.php?attachmentid=2165&stc=1&d=1319157353

    attachment.php?attachmentid=2166&stc=1&d=1319157360

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    attachment.php?attachmentid=2168&stc=1&d=1319157371

    attachment.php?attachmentid=2169&stc=1&d=1319157379
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #18
    Re: XW-MPPT60 Config

    Green strip for solar, white for grid.
    attachment.php?attachmentid=2170&stc=1&d=1319157734

    attachment.php?attachmentid=2171&stc=1&d=1319157739

    attachment.php?attachmentid=2172&stc=1&d=1319157745

    8)
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #19
    Re: XW-MPPT60 Config

    So far everything seems to be working as it should, mounted the relay in a plastic box safe away from fingers! Happy with the outcome, now I just need to get power to the basement :roll:
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