At least 2 issues with my system

gicamucigicamuci Registered Users Posts: 26 ✭✭
edited October 18 in Solar Beginners Corner #1
Hello everyone :)
I am located on the north coast of the Dominican Republic and while having lots of sun, heat is my main enemy here...
My battery bank consists of Trojan's T105Plus 225Ah @ 6V batteries and it is configured in two parallel strings of eight each for a 450Ah @ 48V.

First issue I have is battery temperature difference between the two strings. I have the Outback temp sensor that reads the temp on the string that gets really hot - sometimes as high as 45C. Ambient temp is all the time 35C at noon. I also have a big industrial fan that will run when battery temp is reaching 32C. Without the fan, about half way into absorbing time and sometimes in Floating, the FM80 will say "BatTooHot".
Second issue, which I think it is related to the first one is the absorbing amps won't decrease. I have the FM80 set for 2% of bank size end amps and the timer at 2 hours. Temp compensation is set to Wide.

My question is, could this indicate a battery failure in the string that gets hot ?

I do have a temp compensated hydrometer, but before I dive into that measurement (my age, too hot outside, lots of cells to check and I am trying to stay off grid) I would need some input from some of you guys with more experience.

5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
8Kw Champion LPG gen for emergencies only.
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    Gicamuci, welcome to the forum.

    Lead acid batteries do not like heat... And while charging up to ~80% state of charge, the batteries do not generate too much heat, as you go over 80% to 90%+--That is when the batteries start gassing (bubbling) and generating more waste heat. And at 45C--Those batteries are too hot to charge. (more or less, there is an engineering rule of thumb... For every 10C/18F increase, the "thing" ages 2x faster--Or has 1/2 the life. 25C being "room temperature", 45C is 1/2 * 1/2 = 1/4 the battery life).

    A real quick look at your configuration... 450 AH @ 48 volt battery bank... More or less, a 4.5kWatt AC inverter and 4.5 kWatt of solar panels is about the maximum for that battery bank (what lead acid batteries can supply over time/temperature/state of charge reliably).

    Anything over that, having a remote battery temperature sensor is good (battery charging voltage is reduced as batteries get hot). And having more solar panels can help keep the battery bank properly charged (under charging batteries is probably the #1 cause of early battery failure).

    Things that can help, placing batteries in a cellar/bermed earth/etc. can help keep batteries cooler... And some folks have even used a water bath (cold water, or even refrigerated water) to cool the batteries. But at this point--You have what you have.

    Personally, I like to call the battery bank the "heart" of your system. And understanding what is going on there is where I like to start (and proper charging, avoid over discharging, avoid deficit charging--too much load, not enough charging, etc.).

    First--What is your charging voltage set point?
    Do you have a hydrometer (check battery cells for specific gravity/log temperature corrected for each cell once a month, etc.).
    Do you have a Voltmeter or, ideally, an AC+DC Current Clamp DMM (digital multimeter).
    https://www.amazon.com/UNI-T-Digital-Handheld-Resistance-Capacitance/dp/B0188WD1NE (inexpensive, "good enough" for our needs)
    https://www.amazon.com/gp/product/B019CY4FB4 (mid priced meter)

    So, we need to know your charging voltage--And for deeply cycled batteries, you really want to look more at 6 hours of absorb--2 hours is a bit short.

    Also, how much water do you need to add to your bank? If you need to add water once a month or more often, you may be over charging. If you need to add water only every 4 months or less often, you may be under charging.

    If your batteries are getting over 10% rate of charge--That is good... With your array, the maximum charging current (rarely will see on cool/clear days a few hours a year):
    • 5,100 Watt array * 0.77 panel+controller deratings * 1/58.0 volts charging = 67.7 Amps (near noon, into a discharged battery bank)
    Checking specific gravity and using a voltmeter on each battery (log the readings). You are looking for general state of charge and for batteries that have higher or lower than the rest of the bank voltage (check charging, discharging, resting)... Batteries that are "different" may have dirty or corroded terminals/cables, or have an open or shorted cell, etc.

    In tropical climate--Hot FLA batteries are problem. Keeping them cool (shading/ventilation/building construction/etc.) to the best you can is important. But you are probably not going to "fix" that soon. Longer term, Li Ion batteries may be an interesting replacement (LiFePO4 type--They are more efficient and run much cooler vs FLA batteries--Some other advantages, but they are $$$$ vs simple lead acid batteries).

    If you have a current clamp meter, you can measure the charging/discharging current for each battery string and see if they are properly sharing current, or if there is something wrong (bad connections, bad cell(s), etc.).

    Also, I have a question about your solar array. What Power,Vmp, Imp rating are your panels? And how many panels do you have in series (Vmp-array). Your signature says you have 19 panels(?). Normally, you would have 3 or 4 panels (or so) in series, times X panel strings in parallel. 19 panels does not divide equally. You want the Vmp of your array for a 48 volt battery bank to be >~80 Volts Vmp-array minimum. If your Vmp-array is too low, you will not get optimum voltage for your charge controller (and less charging current). Too high of Voc-array, and it can damage your charge controller...

    Also, you can better understand how your system is working. You can check the current on each solar panel string (all should be equally sharing current), confirm the output current and voltage of your charge controller, battery operation, and your loads (i.e, 60 amps out of charge controller and 30 amp load, means only 30 amps is going to your battery bank).

    Once you get the battery situation stabilized--Then can start to look at other parts of your system (as needed).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivormcgivor Solar Expert Posts: 3,613 ✭✭✭✭✭✭
    edited October 18 #3
    In addition to the above, can you post how the parrallel battery string are connected with emphasis on where the output and input are positioned. Sounds to me like there is imbalance which causes one string to be favored, or one battery or cell may have failed, measuring the individual 6V batteries may provide useful information.

    Being in the tropics as well I'm no stranger to high temperatures, both my previous lead acid banks failed in the manner you described, if the batteries are at or near 3 years old it may be time to consider replacement as that's the tropical life expectancy , at least in my experience. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    edited October 19 #4
    I do have a temp compensated hydrometer:
    https://www.amazon.com/dp/B007CW8Y9S/ref=cm_sw_r_cp_apa_i_3tyJFb36G7Z1M
    And a clamp meter:
    https://www.amazon.com/dp/B01N014USE/ref=cm_sw_r_cp_apa_i_isyJFbSKN43CQ

    Will check the battery string in question.
    I also have this meter to monitor what's going on:
    https://www.amazon.com/dp/B07B4CWKRJ/ref=cm_sw_r_cp_apa_i_nhyJFbGQBJ4AX

    The panels I have them connected like this:
    3 strings of 4 in series x 250W = 3kW
    1 string of 4 in series x 275W = 1.1kW
    1 string of 3 in series x 330W = 0.99kW (this one drives my solar pool pump, but on cloudy days I can add them to the rest of the system, at a flip of a button)
    All panels are around 30V @ 8A, I don't remember the exact values, but I took pictures of the labels, only I don't have them handy right now.
    The FM80 is a 150V @ 80A CC. Sometimes around 1 or 2 PM I can see the voltage around 120V.
    Almost every day I have a production in excess of 20kW and sometimes even close to 25kW.
    House load is 0.5 to 1kWh, but sometimes could be more, for short periods, if the microwave is in use for example.

    Another thing that came into my mind is (since I bought 16 of them) the battery shelf age at the time I bought them two years ago. Could a difference in manufacturing date cause issues over time ? Trojan is stamping the production month and year on the negative post of each battery. I'll have to check that too cause I can see different values.

    The batteries I have them on an open rack on two levels. The lower level is the one with the temperature issue. They are off the ground by 5 inches or so. All connections from CC and inverter are going to the upper level first and from the same posts are going down to the lower level (3feet of 1/0AWG cables).
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    BB. said:
    Also, how much water do you need to add to your bank? If you need to add water once a month or more often, you may be over charging. If you need to add water only every 4 months or less often, you may be under charging.
    The string that gets hot needs watering each 2 or 3 week while the cooler string close to never.
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • mcgivormcgivor Solar Expert Posts: 3,613 ✭✭✭✭✭✭
    Classic symptoms of string failure due to a cell, or cells not performing, have you taken SG readings? and how old are the batteries? 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    SG would be my next step to discover the faulty bat.
    Batteries are 2 years old.
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    OK... Sounds like the hot string either has a shorted cell, or the the cold string has an open cell and/or your charging voltage is too high (one string has no current flowing through it, and the other string is getting over charged).

    Do you have a voltmeter? Need you to to measure the voltage of each battery (6.xx or 7.xx volts per battery) and the voltage of the whole string (50.xx to 60.xx volts) while charging (or at least let us know if the string is charging in the morning, or you measured voltage at night under load).

    And do you have a hydrometer to measure the SG of each cell... Again, need to write down the SG of each battery and the average temperature (SG changes with temperature too). Will usually be somewhere between 1.000 (water/completely discharged) and 1.280 (fully charged).

    https://www.solar-electric.com/search/?q=hydrometer

    After you have measured the SG of all your cells, rinse the hydrometer out with distilled water. If you leave electrolyte inside, it will dry out and get they hydrometer float sticky.

    How much experience do you have with electricity and batteries?  Each battery (in your system) has 3 cells, each cell being around 2 volts. So 3x cells in series = 6 volts per battery. And 8 batteries in series is 48 volts. Each cell should be matched in a string. If you have one dead cell, then the string cannot function.

    When you put two strings in parallel, the capacity adds. 225 AH per string * 2 strings adds to 450 AH. Each string should be "matched" in voltage and current flow.

    Failures of cells/strings/batteries. A shorted cell has near 0.0 volts, and the whole string will be at 46 volts. In parallel with a 48 volt string, that shorted string will continuously be over charged by 2.0 volts. And no supply any useful current until the other string is mostly discharged. If you have an open cell, that string is just like a broken wire--And no current will flow and it will be almost like the string is disconnected from the whole bank.

    If you have a failed cell--Almost always that battery needs to be replaced. It is uncommon to fix a failed cell/battery. Sometimes, you can have a "weak cell" (low SG, and/or low voltage) by charging at a higher voltage for a day, cycle down over night, and charge again at a high voltage (equalize charging). And EQ charging is usually done once a month for a few hours to bring up any weak cells.

    However, continuous EQ charging is hard on a battery bank too... It causes lots of water usage and the bank to run hot/overheat while charging.

    In a hot climate like yours--A FLA battery bank will probably last something like 3 years or so--Especially if they are running as hot as yours
    You can try other things too--Like disconnecting the "hot string", and seeing how the system runs on the other string. If the string is OK, you may be able to limp along until you fix the hot string (replace one battery). In the end, depending on how old the bank is, and what is failing--You probably need to replace the whole bank and make sure everything else is OK.

    Checking that the bank is properly recharged every day (or every few days) to >90% state of charge. Make sure that loads have not grown to where the bank is getting "deeply cycled" every day cycling. Running down to ~75% state of charge every day (overnight), and down towards ~50% State of charge during bad weather/day of heavy load and then get recharged >80% the next day is normal. And getting back to >90% State of Charge at least a couple times a week is critical too.

    The bank that is using water every few weeks sounds like it is over charging (and you may find one or two cells not using much water at all--if that cell is shorted). The bank not using any water at all either has an open cell and/or you have a bad battery connection. It is probably not supplying much current at all.

    Be very careful here... A battery that is "boiling dry" can catch fire or even explode from the hydrogen gas created during charging (if the plates are exposed, and all the water is "boiled" out of the battery from overcharging). Probably will not happen to you--But this is not a stable situation at this time.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    BB. said:
    You can try other things too--Like disconnecting the "hot string", and seeing how the system runs on the other string.
    So last night I switched to grid after 2 hours of absorbing and sometime spent in Floating. I wanted to have them probably close to full so I can "play" with them this morning. Around 8AM I switched off-grid. Half hour ago, around 11AM, I did what you just mentioned above :)
    CC was in Bulk mode and as soon I disconnected the hot battery string, it immediately went to Charged and then Floating.
    I'll let them (the hot string) sit for 2 or 3 hours and proceed to the fun of SG testing them.


    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    Really need to see some numbers here... What was the charging current and battery bank voltage? What was the voltage of each battery (I would also like to confirm the FM80 bank voltage reading with a voltmeter measuring the bank voltage--There may be a difference, some charge controller give the 25C "temperature corrected charging voltage and others while give actual bank voltage). For example:
    • typical battery cell voltage offset is -0.005 volts per degree C per cel
    • 24 cells in series * -0.005 volts per cell = -0.12 volts per degree C
    • 45C batt temp - 25C standard temp = +20C offset
    • +20C * -0.12V/C = -2.4 volts
    • 14.8 volts charging (12 volt batt) * 4 = 59.2 volts charging nominal @ 25C
    • 59.2 volts setpoint - 2.4 volts (@ 45C batt temp) = 56.8 Volts actual charging voltage @ 45C
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    I have two digital meters (one being a clamp one as posted earlier, but the message did not appear yet) and this monitor https://www.amazon.com/dp/B07B4CWKRJ/ref=cm_sw_em_r_mt_dp_rGBJFbVET0K3A connected to my system.
    After some measuring, ended up going for a median voltage and backed down the FM80 by 0.2V.
    The outback temp sensor connected to the FM80 (which is set for Wide compensation) gets the exact voltage as you mention, 56.8V around noon. Mornings are a bit cooler and the voltage is close to 59V, but not for long. By 11AM there's 32C to 35C here.




    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    Sorry Gicamuci, you post #4 was caught in our spam filter... Should not happen again.

    Your 3 solar panel strings look OK... Need to check Voc*4 does not exceed Vpanel-max on a cold day (not that you have "cold days" there).

    The 3x string + backup string--You need to check the Vmp-array is OK or not... Generally, you want the Vmp-array to be within ~10% or better:
    • 4 * 30 Volts Vmp = 120 Volts Vmp-array (standard temperature)
    • 3 * 30 Volts Vmp = 90 volts Vmp-array--Way too low to be useful with 120 Vmp nominal string
    • 3 * 36 Volts Vmp = 108 Volts Vmp-array (better if these are "higher voltage" panels)
    • 120 V Vmp * 10% = 12 volt miss match
    • 120 - 12 = 108 Volts ... Sort of close enough if you are running Vmp~36 volts for the 330 Watt panels
    Your system (excluding the batteries) seems to be operating OK... You need to look at each battery in the system (and each connection) and see what is happening.

    Your options look to be:
    • replace one or two "bad batteries" with "bad cells"
    • replace entire "hot string"
    • run on "cold string" and see how that works (your want your system stable before buying $$$$ new battery bank)
    • replace whole bank--Especially if bank is >~3 years old
    This website does a nice job of describing how to parallel battery banks... Doing it correctly helps ensure that each string shares the total current correctly.

    http://www.smartgauge.co.uk/batt_con.html

    First, this is your money, not mine... So we respect your choices here. Changing out one or two batteries is just a short term solution--In months (or a year???) the bank will probably need to be replaced.

    It is really important to figure out why you are having problems. The "hot bank" with shorted cell(s)--That can be simply age, or if contaminated water was used instead of distilled/deionized water was used.

    Open cells--Could be if the battery bank sat at low state of charge (75% or less for months, or taken towards zero state of charge ever)...

    But--Those are just guesses... Vibration/damage during shipment operation (fixed bank--not in a vehicle). Over charging can cause battery grids and lead plates to corrosion and expand (see the positive post being "pushed up" out of the battery case). And Heat+Age kills batteries... (45C = 1/4 battery life)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    And here are the numbers on the hot string:



    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,580 ✭✭✭✭✭
    In case Bill is doing other things I will jump in. I did not read all of this but your SG's are all over the map.

     Do you equalize these batteries?

    I am doubting it. They need EQ badly!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    Thanks Dave.
    I did try to EQ them, but because of the heat the CC will go into BatTooHot.
    And that while trying to compensate for temperature because the FM80 won't compensate for temp while in EQ mode. So instead of EQ them at 64.8V I tried to use 62.4V.
    Problem is this hot string won't want to go that high no matter what :(
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    edited October 19 #16
    Can you tell us the charging current to the batteries? Whole bank, and by string?

    First guess... Battery #1 is toast. Battery #2 is weak, and replacing would not be out of the question.

    Notice there first two batteries also have low terminal voltage compared to the rest of the string. And this makes sense as SG is related to cell voltage (on my phone, so cannot lookup the offset... But roughly, -0.040 lower SG is about -0.040 volts for that cell).

    For EQ charging, the charging current should be 5% of battery AH rating (0.05x225AH=11.25 Amps) to 2.5%... you do not need or want >>5% EQ charging current as this will already do a good job of battery heating.

    Might as well start with the cool bank next and see what is happening there.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,580 ✭✭✭✭✭
    Yea EQ the cool bank after charging it. Might take more hours than you have left today.
     It is going to need many hours of EQ and you may still never get the cells close. 

    Multiple strings is always a less than desirable choice.  Next set should be L16's in one string.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    I don't know what L16 batteries are :(
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    L16 are just larger battery cases.

    And you can get them in several different voltages.


    For 6 volt batteries, they are around 400 ah.

    Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    edited October 20 #20
    So I had the hot string of 8 absorb for 2 hours yesterday and this morning they were on Bulk until 9:30AM
    Since then they are in Absorbing now and I guess even though the timer is set for 2 hours, the CC will end the absorbtion sooner. There after will get them to EQ. I will manually compensate for temperature, so instead of 64.8V will go for 62.4V
    But for how much time ? 
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,580 ✭✭✭✭✭
    2 hours min then rest for 30 minutes. Find the worst few cells and number them. Compare them with the 1.280 cells. You do not have to measure all the cells again. You want them to all be within .030.  Start the EQ again. Do not do this overnight or when you are not around. Batteries that have not been maintained with EQ can do weird things. Good Luck
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    edited October 20 #22
    Some weird thing on the CC, when in MPPT EQ it jumps from 0amps to around 50A and then back down again. Not all of a suden, but fluctuates like that and never gets to 62.5V
    It goes up to around 59V. Should I wait for more output from the PVs later on ?
    I don't understand why the high current :( and fluctuating.
    Battery number 6 is really boiling...
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    The batteries near full charge SG (1.280 is probably the highest you will see--1.260 to 1.280 is usually full charge for FLA batteries) are te ones that will bubble/run hot during EQ. The low SG batteries should be charging and not doing much gassing or heating--At least until those batteries get near full charge/SG... If you do not see the SG going up during EQ--Then they not recovering.

    Full charge SG is around 1.260 to 1.280 units, although, in tropics some battery companies will fill with slightly lower SG electrolyte for longer battery life.

    Note that EQ is hard on batteries--Especially the "good batteries" that already have good SG readings (gassing erode plates, Oxygen corrodes grids and plates, heat also damages batteries). Gassing and Heat is where the charging energy goes for fully charged batteries in a string that is being 

    If you had a 6 or 12 volt charger handy--Switch over to the other battery string and use the AC charger on the 1 or 2 "weak" batteries and charge just them. That will limit damage to the rest of the "good batteries" in the string.

    Depending on the charging current, you should measure an increase in the SG of the weak batteries during charging/EQ... If you do not (the SG stays constant), then you are (most likely) just wasting energy and distilled water.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    I actually do have a 6/12V charger from Battery Tender ( https://www.amazon.com/dp/B07XMJDJX7/ref=cm_sw_em_r_mt_dp_Z3WJFb8850HKQ?_encoding=UTF8&psc=1), but is just a 4Amps charger and is going to take awfully long to charge those 2 batteries.
    Since yesterday the SG did raise indeed in those 3 cells that were reading 1.220
    Hopefully they will get up and running again.
    Thanks everyone for all your comments. Very much appreciated. And I will report back once those 2 are charged up.

    Alex
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    As always, read the user manual for your batteries:

    http://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf (page 22, table 7 has SG vs charge)

    A 1.217 SG is around 70% state of charge (needs to be temperature corrected for hot batteries--if you did not already correct).
    • 225 AH * 0.3 state of discharge = 67.5 AH
    • 67.5 AH / 4 amp charger = 16.9 hours
    I would not feel bad to charge those one or two batteries on a 4 amp charger for 24 hours and see what happens to them... Better than "cooking" your "good" batteries.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    edited October 21 #26
    I actually do have a 6/12V charger from Battery Tender ( https://www.amazon.com/dp/B07XMJDJX7/ref=cm_sw_em_r_mt_dp_Z3WJFb8850HKQ?_encoding=UTF8&psc=1), but is just a 4Amps charger and is going to take awfully long to charge those 2 batteries.
    So it took 24 hour just to bring this close to death battery (number 1) to Absorbing with the small 4A charger.
    I guess by tomorrow morning should be on Float.
    Next will be number 2.

    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    How is the "cool battery bank" doing?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    The cool bank is doing great. Yesterday by 1PM they were already on Floating, after overnight I used them down to 65% SOC. They take 50 to 60 amps in Bulk while staying roughly a bit above ambient temperature. It was 33C in the casita and they were at 35C. I had them absorb for 2 hours.
    7AM and I just checked on number 1 on the hot bank and it is still on Absorbing.
    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,580 ✭✭✭✭✭
    Keep in mind that one of the worst things you can do for long battery life, much worse than too much EQ, is to hit a battery that size with 50 or 60 adc. You need to limit the initial charge current. Longest battery life is around 10% or a bit more than the AH capacity of the battery. 
    What is gicamuci ? Just curious as I use to know a guy with that name.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • gicamucigicamuci Registered Users Posts: 26 ✭✭
    The so called "hot" battery bank is now offline while I try and bring up the two batteries that were low on SG.
    Those around 50A are going to the online good string of batteries that have 225Ah @48V.

    gicamuci means "Gică" (a name, much like George in English) plus "muci" which means snotty (in English, mot-a-mot), but I am using is more as "novice". So something like "novice George". I was born, raised and lived in Romania until I turned 30. So that's a Romanian "thing" as my name is not George, but Alex.

    5.1kW, 12 × 250W + 4 x 275W + 3 x 330W solar panels , FM80 MPPT CC, WavePower 6kW pure sine inverter, 16 x Trojan 105Plus in 8s2p strings 450Ah @ 48V battery bank.
    8Kw Champion LPG gen for emergencies only.
  • BB.BB. Super Moderators, Administrators Posts: 31,188 admin
    Have you checked the specific gravity on battery #1 yet? Has it risen a good amount after two days of charging?

    If you have 2x batteries you wish to charge and a 6/12 volt battery charger--You can put both in series @ 4 amps and bring them up together... Then when one battery has good SG--You could take the "charged battery" off, and continue to charge the low battery at 6 volts.

    And watch the resting voltage for a number of hours/day off charge--See if the voltage/SG "crashes", or stays where expected (around 12.7 or 12.8 volts for a fully charged 12 volt battery--Or 6.35 to 6.40 volts for a fully charged FLA battery "resting" after 3+ hours off charge/loads...

    If the SG is not going up and/or the battery voltage falls significantly after "resting"--It may be time to look at either a new bank--Or at least replacing the 1 or 2 weak batteries and get that second string back online. The single "cool string" is being hammered pretty well with your present usage and a second string is really needed (for loads/65% discharge overnight/high charging current).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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