Equalization current for flooded batteries questions

mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
Having replaced a Morningstar TS 60 PWM controller with a Schneider 60-150 MPPT, i've noticed during equalization the Schneider has an algorithm completely different from that of the Morningstar. The Schneider has a one hour EQ with a high current, ~25 amps on a 24V nominal 260Ah battery, battery Ah is programed correctly. The Morningstar on the other hand has a 3 hour EQ at a much lower current, usually around 6 amps if memory serves me right. Many say that an elevated voltage with low current is the normal profile. So the question is, does Schneider assume, being a solar charger, there may not be enough hours in the day to fully charge then do an extended EQ of 3 hours, hense the one hour at higher currents and if so could this in fact be detrimental, your thoughts and opinions will be greatly appreciated.
  1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

Comments

  • Marc KurthMarc Kurth Solar Expert Posts: 411 ✭✭✭✭
    Equalization is only performed on a battery that is fully charged, so the current draw should be comparatively low when the voltage ramps up to the equalization level.

    You can set the max current, which the charge controller will achieve by reducing the voltage - but the whole point is to hold the higher Equalization voltage.  I don't see a need for limiting charge current, because the increase in current draw will be transitory anyway.

    I always have more questions than answers. That's the nature of life.
  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    Is the EQ temp compensated with a properly working remote sensor? It sounds like either the battery wasn't really full before the EQ, or the EQ voltage is too high relative to temp. IMHO the EQ should only draw more than a small current for a short time (while voltage rises from Vabs to Veq), then just take a couple amps to hold it there.

    Also, I assume the 25a is really net to the battery (not including any loads).
    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
  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
    Equalization is only performed on a battery that is fully charged, so the current draw should be comparatively low when the voltage ramps up to the equalization level.

    You can set the max current, which the charge controller will achieve by reducing the voltage - but the whole point is to hold the higher Equalization voltage.  I don't see a need for limiting charge current, because the increase in current draw will be transitory anyway.

    The voltage programed for EQ is at 32V , the current  limit is programable but currently set high, 50A to satisfy opportunity loads, didn't think it nessary to reprogram to perform an EQ. The CC will only go into EQ if fully charged, or 2% current vs  battery Ah capacity, once this is satisfied the voltage rapidly climbs to 32V , along with the current,~25A, the count down timer displays time left in EQ and holds this current until termination, one hour. The batteries are approaching their end of life, so perhaps this is a factor.
    The voltage is temperature compensated, no loads present, to answer questions whilst writing this, the one hour EQ is the curious question, longer slower, or hard and fast, perhaps someone with Schneider experience can shed some light 
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • littleharbor2littleharbor2 Solar Expert Posts: 704 ✭✭✭✭
    edited June 8 #5
    Sounds like a question for @Dave Angelini.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • Marc KurthMarc Kurth Solar Expert Posts: 411 ✭✭✭✭

    To be clear, I think that you have said that:
    Your Morningstar controller would hold EQ voltage, but the batteries only drew 6 amps.
    Your Schneider controller holds the same EQ voltage, but the batteries draw 25 amps.
    I can't wrap my head around that.
    Was the current draw with the Morningstar low because it wasn't reaching the equalization voltage?

    If you meant that you only want to hear from people with Schneider experience, I will stop now.

    Marc




    I always have more questions than answers. That's the nature of life.
  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭

    To be clear, I think that you have said that:
    Your Morningstar controller would hold EQ voltage, but the batteries only drew 6 amps.
    Your Schneider controller holds the same EQ voltage, but the batteries draw 25 amps.
    I can't wrap my head around that.
    Was the current draw with the Morningstar low because it wasn't reaching the equalization voltage?

    If you meant that you only want to hear from people with Schneider experience, I will stop now.

    Marc





    The Morningstar reached the voltage but at a lower current for a longer period.
    The Schneider reaches the voltage at a higher current for a shorter period,, 1 hour vs 3 hours 

      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
    @ Marc Kurth, sorry, not just people with Schneider experience, although they would be helpful, Amy input is welcome , thanks,  your coments are valuable and appreciated. 
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Marc KurthMarc Kurth Solar Expert Posts: 411 ✭✭✭✭
    mcgivor said:

    To be clear, I think that you have said that:
    Your Morningstar controller would hold EQ voltage, but the batteries only drew 6 amps.
    Your Schneider controller holds the same EQ voltage, but the batteries draw 25 amps.
    I can't wrap my head around that.
    Was the current draw with the Morningstar low because it wasn't reaching the equalization voltage?

    Marc

    The Morningstar reached the voltage but at a lower current for a longer period.
    The Schneider reaches the voltage at a higher current for a shorter period,, 1 hour vs 3 hours 


    But the battery determines the current draw based on the voltage being applied. At any given voltage, a battery will draw exactly the same amperage from whatever is applying that voltage (Assuming that the power is available)

    The only way that a charging source can control amperage draw by the battery is to change the voltage being applied to it. A charging source cannot increase the battery charging rate, unless it increases the voltage.

    I'm wondering if your battery(s) have developed a partial short. That would explain the higher 25 amp draw at the same voltage that previously caused the battery to draw only 6 amps.

    Just thinking out loud, because something doesn't make sense.

    Marc
    I always have more questions than answers. That's the nature of life.
  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    It's not making sense to me either. If the change in behavior happened when the CC was changed, it mostly (but not entirely) rules out the condition of the bank.

    Have you checked SG at any point(s) in the process? It may help to know if the end of absorb really is at fully charged.

    It might also be worth checking actual voltage at the bank and manually working out the temp compensation as a sanity check to be sure the CC is properly compensating.
    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
  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
    Perhaps there may have been  some oversights on my behalf, including factors such as cell ballance being different during the respective EQ's. It is entirely possible the Morningstar may have begun at a higher current during the first hour without my noticing, as it was not a concern at that point in time, tapering down in the latter stage, hour 3. It would be reasonable to assume the battery will accept all the current it can absorb at a given voltage, baring an internal short, so my observation during the Schneider's 1 hour EQ may merely be anxiety, if the EQ were allowed to continue for 3 hours it may well terminate with a lower current. Should this be the case, it may indicate the battery needs a longer time in EQ than the 1 hour fixed Schneider default, which seems short, all literature I've read indicates a longer cycle. All cells have ballanced SG at 1270, string charge/discharge currents  close and individual monoblock voltages within 0.05V, but the battery is nearing end of life.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Marc KurthMarc Kurth Solar Expert Posts: 411 ✭✭✭✭
    I would concur with that!
    I always have more questions than answers. That's the nature of life.
  • WaterWheelWaterWheel Registered Users Posts: 242 ✭✭✭
    I also have the 1 hr Schneider EQ with my 80-600.        The current drops as it gets further into the EQ or if after the 1st hr of EQ I program in a 10 minute absorb and another hour of EQ.        After the 1st 15 minutes on the second EQ  the current continues to drop.

    I really with there was a way to program the Schneider to go for a longer (like 3 hour) EQ so I could terminate it manually when SGs evened out.

    Conext XW6848 with PDP, SCP, 80/600 controller, and conext battery monitor

    18 SW280 panels on Schletter ground mount

    48v 790 amp/hr Crown battery bank

  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
    I also have the 1 hr Schneider EQ with my 80-600.        The current drops as it gets further into the EQ or if after the 1st hr of EQ I program in a 10 minute absorb and another hour of EQ.        After the 1st 15 minutes on the second EQ  the current continues to drop.

    I really with there was a way to program the Schneider to go for a longer (like 3 hour) EQ so I could terminate it manually when SGs evened out.


    Will try  a second EQ next time to see if it in fact drops, I would agree with having the option to extend the 1 hour as useful, the engineers who developed it must have had their reasons, perhaps a cautionary one, like no auto EQ capabilities, just a reminder, which personally I think is better, strange things could happen if you are not there to monitor and they usually happen that way.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • VicVic Solar Expert Posts: 2,815 ✭✭✭✭

    Flooded batteries that are otherwise is good condition,   but  seriously need an EQ  will require considerably more current (into the battery),  than will the same size/age battery  that on needs a mild amount of EQing.

    Older batteries that are in generally good condition,   seem to have EQ currents that are higher on exiting EQ,  than those which are young..

    Like to watch the measured battery current (Shunt current) when the EQ is done,   this can be an indicator of general battery health.

    This is relative to batteries that have received a full charge preceding the EQ,   and  for Veq that is temperature compensated,   and for Veq settings that are the same,  when comparing Ieq ...   in general.

    It is certainly true,   that just as in Absorption,   the battery charge current depends upon the Vabs (or Veq),   AND Acceptance of the battery.   Increase the Vabs (or Veq),   and the measured battery current will increase,   and taper over a period of time.

    Just my observations,     FWIW,   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.
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    It might just be end of life drama, but if the battery is accepting 25 amps, I doubt it is getting fully charged. I don't know the size of the battery bank, but from your profile, it's between 200 and 460 ah.  so 25 amps represents >5% charge rate. I think I get about a 20 ah into my @660 Ah battery at the beginning of equalizing and I've got a pretty bad cell in it.

    I think Marc has already said, the charge controller really only increases the charging voltage to allow the current to flow into the battery. The current is regulated by what the battery will accept.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
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