Does this sound right



  • HumMichaelHumMichael Registered Users Posts: 26 ✭✭
    > @Estragon said:
    > I think the main issue with shallow cycling is eventually the electrolyte can stratify, with stronger acid on the bottom and lighter, weaker acid in top. The weaker acid acts like a partly discharged battery and can lead to sulfation damage.

    On this note when I was using my hydrometer today, I have one with suction bulb, the first reading is quiet lower than if I release the solution back and suction it again.

    Maybe I am getting the higjer solution sitting at the bottom.

    I may pump the fluid to mixup the solution once in a while. Any thoughts?

  • VicVic Solar Expert Posts: 3,185 ✭✭✭✭
    edited March 2017 #33

    First,  one of the main detriments to shallow-cycling Flooded batteries,   is that this can cause Lead Dioxide to clump on the positive plates.   This can be mechanically damaging to these batteries.   Most battery manufacturers plot Cycle Life from SOC of 90% and below.   Cycling these batteries with less than about 10% DOD is not good for them in general.

    Regarding measuring SGs,   it is usually best to draw and return two or three samples on each cell before drawing the sample on which the reading will be taken.   Be certain to hold the Hydrometer vertical as the reading is being taken.

    The Measuring SG article,  linked earlier in this Discussion is a good summary to get good results in measuring SGs.  Just make certain to rinse the Hydrometer at least three times with Distilled Water when you are done measuring SGs.

    FWIW,   Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AkoAko Registered Users Posts: 168 ✭✭
    Me Remote temperature sensor has arrived at last and fitted it and its dong what it should , colder temperatures it increases the target voltage correctly as expected and visa versa .

    Had a reply also from the tech guy at Rolls in Spain and as i read it only adds to the general confusion of knowing what voltages to charge the batteries at . I asked why he earlier gave a Bulk / Adsorption voltage of 29.8 for 10c when Rolls show 30.6 . Using Rolls set points the SG reaches 1.265 by the end of daylight after spending around 3 hours in Bulk before going into Adsorption for the remainder of the day .Temperatures here and on the batteries are now around 25c so i told him i was now using 30v Bulk / Adsorption an equalisation set for every 4 weeks at 31.5v and asked him outright if Rolls figures can safely be relied on . Either im missing something or it appears his opinion differs from Rolls . I have only reached float mode once but that might be due to the way the TS60 operates as explained to me by the Morningstar tech guy so thats not worrying me but arriving at the correct charge settings is .

    Dring a lot of years I am testing and using this batteries. It is only necessary to increase the Voltage level of the batteries for a limited time, when the specific gravity is lower than aprox. 1250 units if the charghe controller has reached the float mode. So an automatic equalize maybe sometimes is not helpful. Only the manual control of ths s.g. every 2 weeks makes sense and will help to garantee a long life time. A generally higher Voltage level is only indicated if you usually do not reach the correct specific g. 
    So there is no general recommendation. It is an individual adjustment depending on a lot of different circumstances. ( speed of recharge and discharge....)

    I have attached a screen shot of the daily Log in the hope it might assist someone familiar with Rolls Batteries to explain the discrepancies . Unfortunately had a couple or really dark wet and cold days so not a lot coming in at all so had to use a generator last night with 20 amps coming in for 3 hours so i didnt cycle the batteries to deep and its clear i will have to do the same tonight .

    Below is the original reply i received when i contacted Rolls (Spain) regarding setting up the batteries when they were new , he temperature that i gave them was 10c at the time  , was only one figure given , no mention of Adsorption time or Equalisation time and duration . i did explain i was charging only with an Offgrid Solar array but he also gave the figures for a Charger (or Charger / Inverter) , i didn't understand why they needed to be different either . but they did match exactly what Rolls themselves give , the only thing that would makes sense is if Rolls only give figures for charging with an charger or an Inverter/Charger , if so why would they not mention that if someone uses these batteries on an Offgrid solar system they should use different figures  .

    Solar Controller:

     Bulk / Absorption: 29.8V

    Charger (or Charger / Inverter):

     Bulk / Absorption: 30.60V

    Charger Current: 50A

    Absorption time: 4 hours

    Equalisation: 31.8V

    Equalisation time: 2.5 hours


    Please note, the above voltages are based on the below mentioned temperature (10°C).

    1840 Watt 24v Array . 4 x 460 Watt Panels 
    Victron Blue Solar MPPT Charge Controller
    4 x 6v 400 Apm/Hr Trojan L16 AGM
    Victron 1200w Multiplus Inverter/Charger
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I'm not sure about the different voltages suggested by the Rolls person, but I can hazard a guess.  They may be thinking you would use the generator-charger at a slightly higher voltage to ensure a good bulk in a relatively short (fuel efficient) time, and finish at a more normal voltage with PV. 

    In any event, the key is to watch your SG levels.  If levels are generally low, this suggests a chronic undercharge which a controlled high voltage charge is meant to correct.   The other thing to watch besides average SG level is discrepencies between cells, in which case the purpose is to bring the weak cell back into balance with the others.  Ideally, the EQ done to correct the second problem would be done only on the battery with the weak cell.  I think the point the Rolls person was trying to make is the need to EQ should be driven by the needs of the battery, not on an arbitrary calendar basis. 

    IMHO, an EQ should always be supervised to make sure water level is okay, temps aren't getting to high, and the EQ stops when the objective SGs are reached.  The remote temp sensor helps, but it only measures the temp at one point in the bank.  It can't tell if one cell is getting too hot, for example.
    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
  • AkoAko Registered Users Posts: 168 ✭✭
    edited March 2017 #36
    Two batteries have a cell each that is lower than the other 2 in each 6v battery , the other 2 batteries are all fairly equal . ie : all around 1.265 when charged and the two odd ones around 1.245 - 1.250 , so i have 10 cells that balance with just the two that dont .There is no way i can charge them individually . The discrepancy used to be greater before an equalisation charge brought them closer .

    I have noticed that when in bulk the voltage from the array is less than half a volt higher than the battery bank , sometimes only a couple of tenths higher but when into Adsorption the difference increases to 2 3 or even 4 volts higher but Current decreases . I have plenty more than that coming in . Have even noticed times when the voltage coming in was reduced very slightly lower than battery voltage while there was nothing being drawn at a time and more voltage was available .

    I have always thought the voltage was needed so if i take the advice of the Rolls guy and go against Rolls own figures and reduce my set point to g into Absorption then my batteries wont get sufficient charge during the day , i would be wasting the opportunity to put more in .

    1840 Watt 24v Array . 4 x 460 Watt Panels 
    Victron Blue Solar MPPT Charge Controller
    4 x 6v 400 Apm/Hr Trojan L16 AGM
    Victron 1200w Multiplus Inverter/Charger
  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    I'm wondering if perhaps a longer EQ is in order, say at around 32V to get things happening, bringing the low SG cells into alignment, not a permanent setting, but just a one time stimulation, the TS60 the dip switch settings don't allow 32V but perhaps with MS View it could be programmed, it worked for me, bringing the EQ voltage up from 30.6V to 32V, all cells became equalized utilising the default EQ of a Schneider 60/150 CC at 32V. Having read extensively into the benifits of equalization it is often stated that a conservative approach is not nesesarally the best approach, however the manufacturer states their limits, should they be broken ? Can't answer that, but from what I've read, Rolls batteries need an aggressive charging regime, although I've no personal experience with them, they are batteries no more no less.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • AkoAko Registered Users Posts: 168 ✭✭
    I programmed the ts60 with msview to do an equalisation for 2 and a half hours at 31.5 and it was surprisingly easy . Rolls state between 31.2 and 31.8 so 31.5 was halfway and was safe as the ts60 is always a couple of tenths of a volt out anyway . Batteries could be heard bubbling bit no gassing that i noticed or water loss , didn't have the remote temperature sensor fitted then so cant say what it was but the batteries didnt feel excessively warm . I did that March 9th so will wait until 23rd and do it again .
    1840 Watt 24v Array . 4 x 460 Watt Panels 
    Victron Blue Solar MPPT Charge Controller
    4 x 6v 400 Apm/Hr Trojan L16 AGM
    Victron 1200w Multiplus Inverter/Charger
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