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BoFuller
BoFuller Solar Expert Posts: 187 ✭✭✭
in Solar Beginners Corner #1
I had my system installed in May of 2015, so I’m coming up on 5 years. It has always worked well, except for my current issue of the Auto-start not working. All I have ever checked on is the SOC level, trying to make sure it doesn’t go below 75% very often. And my experience with the SOC level is just from reading it on the Mate3.
What’s my next step in learning how to maintain? Do I need to get a hydrometer and measure cells? Should I equalize? (I never have)
Is there already a thread that would explain better monitoring skills? Is there a book I should get?
I’m retired now, so I have a little more time to invest in learning.
12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
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    The system must have been well designed for your needs  to have survived almost 5 years without a glitch, particularly with parallel batteries. Low cycle depth would likely have had an influence with longevity especially without checking SG on a regular basis. The attached pdf file explains much of what is required from a maintenance perspective for vented cells, I found it extremely helpful explaining in detail the characteristics of the format.
    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.
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #3
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    So far I can’t open the attachment. It keeps saying Connection Timed Out.
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Worked for me (Chromebook)--3.2 Mbyte download (I have decent Internet speed, and it downloaded in a second +/-).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #5
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    Got it this time.
    I guess I have some reading to do.

    thanks,
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    edited December 2019 #6
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    I would check the specific gravity when your system believes the batteries are fully charged and see how the battery bank is doing.

    If it appears good and even across the cells, I would start a routine monthly equalizing.

    If they are not even and you have some low cells you need to do corrective equalizing. A controlled over charging of the battery bank until the low cells  don't show any improvement for a couple hours.

    https://youtu.be/jCl5klSF4tE

    An inexpensive glass hydrometer can be  had  at most auto supply shops. I'd stay away from plastic hydrometers other than the 'Hydro-volt' imported by Midnite.

    MidNite Solar Hydrovolt Battery Hydrometer

    https://www.solar-electric.com/midnite-solar-battery-hydrometer.html
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #7
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    And always rinse out the hydrometer after use with a few squirts of distilled water to prevent the floats from sticking when the electrolyte dries out.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #8
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    I took readings on every cell and recorded them. A few (4) were in the green (1.27), most (34) in the white range and 8 were in the red range with the lowest at 1.175
    I equalized for 90 minutes and then started taking readings while it was still equalizing. At first I was excited that they were up considerably, and then I did one cell a 2nd time to verify and got a completely different number, and then a 3rd time and got another completely different number; like;
    before 1.20
    after - reading #1  1.260
    reading #2  1.190
    reading #3.  1.240
    I guess I was stirring/mixing up the solution when I squirted it back in each time, but how is the correct way to read?

    After seeing this on several cells, some with the final reading higher than b4 equalization and some with a lower number, I stop the process and figured I needed a new hydrometer.
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #9
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    The cell that was 1.175 stayed there, even after 90 minutes and after several readings.
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #10
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    Make sure you have "bumped" any gas bubbles that may be stuck to the float off... Otherwise you will get "high" / inaccurate SG readings.

    Was the "low cell" bubbling? Or just "dead" while the cells on either side bubbled?

    For the cell that stays low SG... It may be a bad cell and need replacing. What can help is to significantly discharge/recharge/float the battery bank a few times (over multiple days). Sometimes, cycling and aggressively recharging will bring up a bad cell.

    Otherwise replacing the cell/battery (or whole bank if weak) is the next step.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #11
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    I’m sure it was bubbles, now that you mention it. My neighbor said I should wait about 15 minutes after stopping the Equalization before taking a reading.
    I will check them all again tomorrow after they reach 100%.
    I can’t recall now if that low cell was bubbling or not. Probably not, since I got the same reading multiple times.

    thanks!
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #12
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    What is that cell/battery resting voltage (or charging voltage of all batteries in series string)?

    If it is not bubbling, it sounds like the cell is internally shorted.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #13
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    Sorry, I was away all day today. I’ll check it tomorrow.
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #14
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    After the batteries reached full charge today, I measured several cells. The dead one dropped from 1.175 to 1.16. I looked at it when the batteries were at about 96% and it had a few bubbles, about half of what the cell next to it had.

    After batteries reached 100%, I noticed that some cells were up from before the Equalization  (1.19 to 1.23, 1.18 to 1.24) and some were down (!.23 down to 1.21, 1.265 to 1.25)

    It was about 39 degrees in the solar shed when I took the readings. Does the temperature affect the readings?
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #15
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    Yes, the colder the batteries get, the higher the Specific Gravity reads (colder=denser):

    http://support.rollsbattery.com/support/solutions/articles/208145-specific-gravity-temperature-correction-factors

    When taking specific gravity measurements, it is important to correct for temperature to get a true reading. As a rule of thumb, specific gravity will change by 0.0003 points per 10ºF. See the table below:



    The above table shows the actual hydrometer readings of acid at a specific gravity of 1.265 @ 77ºF. As the acid get colder it contracts and the apparent density increases and as it gets hot it expands and the apparent density decreases. This is important when determining the state of charge. If the electrolyte temperature is 100ºF and a density reading of 1.258 is taken and not corrected, unnecessary charging may occur. This will shorten the battery life, waste electricity and unnecessarily gas the battery. Further maintenance from extra watering will then be required.

     

    The best way to measure the state of charge of a battery is to measure the specific gravity. This can been done under load but care must be taken and it is never recommended if the truck is in service. The following table shows varying state of a charge and the corresponding corrected specific gravities of a battery at full charge at 1.265 and 77ºF.

     

    Full charge at 1.265 @ 77ºF

     

    % Charged Specific Gravity

    100% 1.255 – 1.275

    75% 1.215 – 1.235

    50% 1.180 – 1.200

    25% 1.155–1.165

    0% 1.110-1.130


    Battery capacity and battery recharge times are all based on each cell having an electrolyte temperature of 77ºF (25ºC). Temperatures below the nominal 77 ºF reduce the batteries effective capacity and lengthen the time to restore the battery to full charge. Temperatures above 77ºF will slightly increase capacity, but also will increase self-discharge and shorten battery life.


    Major problems occur at temperature extremes. This is the range below 40ºF (4ºC) and above 100ºF (38ºC). Electrolyte in a fully charged battery has a freezing point of about –85ºF (65ºC) but electrolyte in a fully discharged battery with low specific gravity has a much higher freezing point just below 32ºF (0ºC). A fully discharged battery, is endanger of freezing below 4ºC and it should be charged immediately or un-repairable damage will result.

     

    Lower Temperature – lower capacity, more heavily cycled.

    Higher Temperature – higher capacity, more self-discharge and battery wear.



    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #16
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    From the sounds of things the bank is in need of a vigorous equalization at a voltage  around 61.2V with temperature compensation for as long as it takes to ballance the SG readings. Tall cells such as L16 are often subject to stratification, allowing them to gas freely will mix the less dense top layer with the lower more concentrated, reducing eronious SG readings.

    Temperature will have an effect on SG readings which are generally quoted at 25°C 77°F, that is the temperature of the electrolyte not the ambient, http://all-about-lead-acid-batteries.capnfatz.com/all-about-lead-acid-batteries/lead-acid-battery-maintenance/battery-hydrometer-temperature-correction-chart/


    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.
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  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #17
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    Do I have to wait for the normal charging cycle to end before I start Equalization? Or can I start it first thing in the morning when SOC is 83%
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #18
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    Allow it to fully charge before EQ, using a generator to bulk charge in the early morning will help with the time required, ideally there should be no loads during the equalization.
    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.
    · Share on Twitter
  • BoFuller
    BoFuller Solar Expert Posts: 187 ✭✭✭
    #19
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    Thanks!
    12 Kyocera 235 panels, 3 Gyll LiFePO4 batteries (previously 16 Trojan L16 RE-B batteries), Outback 3600W 48V system, Generac 11K propane backup generator, NW AZ, off grid, 6,000 ft (system installed in April 2015)

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