Battery specific gravity help!

Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
edited November 2015 in Solar Beginners Corner #1
All cells but one of my eight rolls surrett batteries are reading 2.75 SG on a midnight solar hydrometer. The Lo is reading 2.55 on the same meter. I have been running equalization for 10+ hours and it has only risen .05 on the cell in question. The batteries went into service 9 months ago. I would rather not have to warrant them out the battery, but it's starting to look like equalization just isn't going to cut it does anybody have any thoughts on this?
100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
Vag woodstove for heat.
Follow our journey at
https://www.facebook.com/ShawnpHarvey

Comments

  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭

    Hi Shawn,


    Think that you are saying  the SG readings are 1.275 on all but one cell.   This is a bit high.  Usually,  the Target SG on Surrette Solar batteries is 1.265 +/-- about 10 points,  nominal.   Are your batteries COLD??


    Suggest that you contact Surrette Tech Support by phone or e-mail to get their read on things.


    Do you have the Surrette Battery manual?  It is available as a .pdf on the Surrette Battery web site.


    More later.   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.
  • Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
    Thanks Vic been awhile since I saw you around I do have the manual and yes they are cold. I ended the day today with the low cell @ 2.60 SG and the rest at 2.70 SG. Rolls is a really good company if I contact them with this issue they will want to warranty out the battery. I'm hoping to not have to.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭

    Hi Shawn,

    Surrette recommends compensating SG measurements by subtracting 3 points for every 10 degrees F (5C)  from readings,  and adding 3 points for every 10 F  variation from their Standard temperature of 77 F (25C)

    If,  after this SG compensation,  you still have mainly high SG cells (and it looks like you will NOT),  then you might try cycling the bank to about 75% SOC,  or even a bit lower.  Each of the larger Surrette banks here have one 4 volt battery which often runs at about 1.280 SG,  and a deeper discharge cycle helps with the balance.

    However,  since your batteries are cold,  you are probably heading into Winter,  and you may not want to discharge your bank too deeply,  now.


    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.
  • Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
    edited November 2015 #5
    Thank you again Vic. I have plenty of solar to meet my requirements even if I completely drained my battery is 100% I would not do this of course but I could if necessary drain them to 75% and easily get them back before dark.
    Let me make sure that we are both on the same page you're suggesting that I take my batteries down to 75% DoD? If this is the case are there any special criteria you would suggest flow rate of recharge?

    P.s this is my system 36 Kyocera 265, midnite solar combiner lightning arrester and breakers, 3 midnight Solar classic lights and 1 midnight solar classic, whizbang Jr, two banks of 6 volt 375 AH Rolls 4000 series @ 24v flex were 500 and to Outback 3624 inverters. I live in snowflake Arizona. My panels are set to 45 degrees (for winter) at true south. On 4 DPW 9 module pole top mounts.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭

    Hi Shawn-H,


    Thanks for the reply,  and a review of your old signature ...  very nice system!


    NO on the DOD of the battery  --  I was thinking of just removing about 25% of Capacity to about 75% State Of CHARGE,  so about 70 - 75% of 20-hour Capacity remaining in the batteries.


    In general  cycling deep-cycle batteries below 90% SOC in each cycle is better for them,  than removing only five or eight percent of Capacity on each cycle.   One side effect of light cycling can cause greater divergence in SG readings,   and,  in time could even damage batteries by allowing Lead Dioxide clumping on the plates (Positive),  which can be damaging.   At least,  this is the common feeling of many.


    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.
  • Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
    I have herd that tho I did not think I fell into that group I cycle my batteries to 60% DOD almost religiously every night. How many cycles would you suggest I drop it and run it all the way back up and would you suggest another equalization anytime soon. I run one every 30 days on an auto start.
    And
    Okay I'll tell the kids to fire up the Xbox and watch TV late they will love you for it. Lol. Thanks for the help again! and if it wasn't for you and photoWatt this off grid journey would have never been possible. This is the best form on the net in my opinion.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    edited November 2015 #8

    Hi Shawn,

    Sorry for my reply delay ...

    You should be fine with your existing cycle-depth.  You should not need to run your bank any lower.

    An Auto EQ is OK,  because,  at least the bank is being EQed periodically.  As you know,  an EQ is a bit hard on a battery bank  --  the cells that have good SGs get overcharged,  and this causes plate erosion,  which equates to some reduction in battery life.   But  not EQing often enough or at too low a voltage is much more damaging to a battery bank.

    Like many things,  it is all about balancing the negatives,  and positives.

    In an above post about compensating SG readings,  I have written that paragraph quite poorly ...

    Let's try it again;   Surrette recommends compensating SG measurements by subtracting 3 points for every 10 degrees F (5C)  from readings for electrolyte temperatures BELOW  77F (25C) ,  and adding 3 points for every 10 F  variation ABOVE  their Standard temperature of 77F (25C).   Sorry for the poor wording.


    Hope that you have a Clamp-on DC Ammeter,  like the inexpensive Sears Craftsman one,  to carefully monitor the balance of charge/discharge currents on the two parallel battery strings.  It is a natural thing for string balance to diverge,  as batteries age differently over time.  Fairly frequent measurement of the SG of each cell will also allow you to see this divergence,  but using a clamp DC ammeter is a quick and accurate (when the meter is correctly zeroed) snapshot of the balance.


    More later,  and no need to try to cycle your bank any deeper than you presently are ...  your batteries must be fairly cold.

    Good Luck,   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.
  • Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
    edited November 2015 #9
    Thank you but I'm starting to think there's something wrong with the entire bank the specific gravity did come up 5 more points putting the cell where it needs to be but all of the other specific gravities are all over the recommended levels and the fluid is starting to become dark in a way I've never seen before.
    P.s. the batteries are only 50 degrees after coldest there currently 87
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
  • Shawn-HShawn-H Solar Expert Posts: 107 ✭✭
    Ok I figured out the issues all of my batteries are reading correct the cell that was bad is still a tiny bit low about three points off of everybody else but I'm willing to bet that corrects itself next equalization.
    So:
    #1 issue specific gravity too high. I added about an eyedropper worth of distilled water to each of the high sales and it brought them into range. Don't ask me how or why but I wanted to make sure everybody was equally topped off once I did they all went back to normal.
    #2 issue one cell extremely low specific gravity. Not sure why my voltmeter didn't pick up the difference in voltage but one of my cables had corrosion in between the cable and the post that I could not see. After correcting it and running a three hour equalization everything looks good not perfect but much much better.
    #3 issue dark water / acid being fairly stressed out about the batteries I seem to forgot that if you do a 10 hour equalization you're going to shed plate material and it's going to be floating around in the water / acid. After 2 hours most of it has settled out and it is much much clearer.
    #4 I'M A DUMB ASS. lol

    Thank you for all of your help it means a lot to me to have somebody to bounce this stuff off of. You're all a bunch of great guys.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
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