Force Bulk Xantrex XW MPPT 60

silvertop
silvertop Solar Expert Posts: 155 ✭✭✭✭✭
in Off Grid Solar & Battery Systems #1
Hey guys,
I just read a thread here where someone does a forced bulk charge every evening. I just tried it and it does work. I'm wondering what the benifit of this is; just to give a battery based system a little more boost at the end of the day ? Especially if I get to float daily. Does this reset the next morning? I have 2 XW 's not on a SCP, that talk on the cat 5 cable and since I started a forced bulk on ONE, it has transitioned to absorb but the second Is still in bulk, and not talking. I redid the forced bulk on both this time hopufully they will reset at sundown.

Suggestions?:confused:
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Force Bulk Xantrex XW MPPT 60

    In general, equalization is fairly hard on batteries... It does not fix anything and can cause early life failure.

    Equalization should be performed when cells are no longer in "balance". Trojan recommends to equalize if the cells are more than 0.030 specific gravity apart.

    And when equalizing, you should measure the s.g. every 30 minutes or so, and when the specific gravity stops rising in all cells... The battery is then equalized. Log the temperature corrected S.G. for every cell and call it 100% full.

    Flooded cell batteries are typically equalized about every 2 months. Some vendors say to equalize at least twice a year (as I recall).

    You should not be trying for 100% state of charge every day--but for >90% state of charge several times a week.

    Why do you think your batteries need equalization? Note you cannot equalize batteries until they are near 100% charged in the first place. Your are pushing current through 100% charged cells to get those cells that are less than 100% full (out of balance) back to 100% full too.

    Over charging batteries can cause positive grid corrosion (oxygen gas is generated at the positive plate and will corrode the positive plate grid to corrode)... One visible symptom of this is that the positive battery posts are pushed up (extruded) out of the top of the case.

    If you believe your batteries are not being completely recharged--Then we need to look at your system. Enough panels, charge controller set to correct voltage, cabling OK, if parallel batteries--are all batteries sharing charging/discharging current properly, absorb timer long enough, etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #3
    Re: Force Bulk Xantrex XW MPPT 60

    I am lost on this one. Time to go outside...
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Force Bulk Xantrex XW MPPT 60

    Dave,

    Since I am trying to convey how I understand equalization should be performed--partially based on my readings of your knowledge/experience--Would you prefer to help with an answer?

    I am trying to mix the reasons why with what to do and not to do.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Force Bulk Xantrex XW MPPT 60

    Bill;

    I think it's terminology confusion again. The OP is talking about "forced Bulk" and you're explaining Equalization. I'm not familiar with the idiosyncracies of the XW controller, but it seems to me this "forced Bulk" is just what you say; turning on the manual EQ cycle to jam some extra current into the batteries at nightfall. I'd also agree it's a bad idea in terms of battery life.

    If you're using a proper charge controller :roll: once there's not enough sun for Float it falls back into Bulk anyway, and tries to put in whatever power is available - without raising Voltage to EQ levels.

    Maybe some Xantrex guru can explain it better. Personally, the more I read of Xantrex equipment the more I like Outback. :D
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #6
    Re: Force Bulk Xantrex XW MPPT 60

    I have 2 XW 's not on a SCP, that talk on the cat 5 cable and since I started a forced bulk on ONE, it has transitioned to absorb but the second Is still in bulk, and not talking. I redid the forced bulk on both this time

    and also I think he is trying to get the 2 controllers to talk with each other? so when the force bulk is set, that the other controller will follow suite?
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  • silvertop
    silvertop Solar Expert Posts: 155 ✭✭✭✭✭
    #7
    Re: Force Bulk Xantrex XW MPPT 60

    This is not EQ just another way to put the XW back into bulk, I dont think I need this, I just found someone talking on another thread here and wanted to know why THEY tried this. My guess if you didn't get to float and wanted to throw it back into bulk this would do it. I dont really understand why you would do this.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #8
    Re: Force Bulk Xantrex XW MPPT 60

    Opps... you are correct.

    Forcing to bulk/absorb cycle again. I, for some reason, read that as forced equalization.

    It should not hurt to force bulk/absorb--but if your battery/charger system is set up correctly, there should be no need.

    How is your "water usage"? Low water usage, probably not enough charging. Using a lot of water, too much charging/too high of voltage/too long of absorb timer.

    Roughly, look at needing to add water every couple months.

    Sorry for the confusion,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • silvertop
    silvertop Solar Expert Posts: 155 ✭✭✭✭✭
    #9
    Re: Force Bulk Xantrex XW MPPT 60

    I think you are correct, I cant see a reason to do this. I think Its just another option. Water useage very normal, I sure do love the long chargeing days in the NW this time of year Im getting about 14-15 hours on line sure hate to see the days starting to get shorter now
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #10
    Re: Force Bulk Xantrex XW MPPT 60

    I still am lost but closer to the trail. The OP wants to force bulk at night on an xwcc with solar? Out for another walk... And thx Bill, you have amazing patience!

    The only thing I ever force at night is happy hour1
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • deacon
    deacon Solar Expert Posts: 33 ✭
    #11
    Re: Force Bulk Xantrex XW MPPT 60

    Please read the last Paragraph before replying to this post.




    I am the one who does a "Force Charge" Around 4pm or so.
    I have (3) XW-60-150 and I have discovered that they only produce what is demanded from your system.

    If my batteries are in float and I am demanding 50 watts of power, then that is all I will get out of them even if at the time they could produce 130 amps.. They attenuate the unused power as heat.

    I have my SCC's set for 180 min Absorb time. With this setting, according to my Bogart PentaMetric, The batteries only reach about 95% before they go into float, usualy down about -25 to -30 AH (1075 Ah bank).

    Around 4 PM I have been hitting the force charge on the SCC.
    This makes them run bulk for about 5 minutes then starts the absorb which I let run until Bogart says they are 100% charged.

    I then start the night with 100% charged battery bank from which I average about 190 AH before the Sun comes up and I start over again.

    Tonight I got to thinking that I wouldn't have to do this if I adjusted the absorb time so I upped it to 200 minutes for starters. Will see how it goes tomorrow. BTW, when I do a charge cycle from the xw4024 inverter powered by the grid, (absorb time set to 180), It goes to 100% charge. I think I just have to do some tweaking with the absorb time to have them floating at full charge by sunset.
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