weird battery problems with Rolls Surrette batteries, SG up to 1.30!

mbzebro
mbzebro Registered Users Posts: 18
I am very excited to have found this Forum. I am a swiss living in southern Portugal and find it very difficult to find someone that has real experience in off-grid solar systems, and especially with "north-american type" wet batteries which seem to be quite different from (in Europe) more common OPzs types.

I have an very annoying story of buying and exchanging batteries in the last 3 months.
Our local PV dealer has started to sell Rolls Surrette Batteries a few years a go and this fall I decided to give up my old AGMs and buy a new bank of 4 Rolls S600 (SG 1.265 6V 600AH) batteries.
I have 24V offgrid System with about 1200W of panels, outback MX-60 charge controller and Studer XPC-2200 inverter/charger.
I use around 60AH every day, the System produces around 150-180AH on sunny days this time of the year.

Before installing the S600 I measured the SG, the readings were low, 1.23/1.235 in all cells.
I charged them and in the following 3 weeks equalized them several times (31 and 32V during 2 hours) but the SG never came higher then 1.24/1.245, which I found inacceptable; they even became worse in week 3 and 4, rising to only 1.22/1.23 even after an EQ.
I also raised the absorb voltage to 30V with no effect.
I checked my system several times with voltmeter and current clamp to rule out an error.
I brought them back to my dealer and they let me "upgrade" to rolls 5000 series 6CS17 (SG 1.265 6V 770AH).
They later said they recharged the S600 and all cells came up to 1.27.
They said I didnt charge then batteries appropriately and they were 100% ok.
I responded they must have been severly sulfated (probably from sitting too long without recharging) since I didnt manage to charge them full even with several EQs and extreme absorb voltages.
The production date on the battery label was mid june 2009, I bought them in mid october.
What do you think?

Unfortunately the weird part comes just comes here.
When I installed my "upgrade" 6CS17 bank, I found out two of the batteries had an SG of 1.26 and two had only 1.22, which I thought was strange.
I recharged the two "bad" batteries seperately up to SG 1.25 and then connected them to the rest.
I cycled them for 4 weeks and stated the following:
the two good (initial SG 1.26) batteries were behaving very well, going up to 1.27 after an EQ and dropping only slowly while discharging.
the two bad (initial SG 1.22) batteries (after 3 hours of 32V EQ) came up to 1.250 (lowest cell) to 1.27 (highest cell).
The SG also dropped significantly faster in discharge.
The voltages of the bad ones are always sigificantly lower.
I just couldnt believe I had a problem again.

At this point I thought I already learnt the these batteries may be "only" severely sulfated.
I informed myself about corrective equalization on the Surrette website.
I did an 9 hour 31V EQ with generator and inverter.
I paused 3 times and checked the temperature, it was a very cold day, the cells didnt heat up much.
The charging current was initially about 28A, slowly dropping to 11A in hour 9.

here is what happened:

all cells of the good batteries came up to SG 1.27; perfect.

after hour 5, all cells in the bad batteries started to come up beyond their previous high SG.
the worst cell came to 1.265
3 medium cells came to 1.270
one cell (previously a medium cell) went up to 1.285!!
the cell that always had been the highest went to 1.30 !!!!
I was stunned and repeated the readings several times.

I wanted to continue the eq to see if the rest of the cells would continue to come up as well, but at this point the battery charger function of my inverter (Studer XPC-2200) stopped working; fortunately the inverter function is still ok.
After a night of normal discharge I checked again, the highest cell still read 1.290!!!

So after an 9 hour EQ the difference between lowest and highest cell has risen from 2 points to 3.5 points!

the next 3 (rainy) day confirmed the SG of the cells in the bad batteries all drop considerably faster then the cells in the good batteries.
What on earth is happening here? Has anybody seen a SG o 1.30 on a standard 1.265 cell? I have a good hydrometer, this cannot be the problem.
What could be the explanation for the faster drop in SG?
All batteries have the same production date, all looked really new. What could be the explanation for the duifference in the initial SG readings (1.26 to 1.22) ?
It is no use talking to my dealer as he is convinced I dont know well how to charge my batteries.
It would be very helpful for me to have some answers before confronting him more seriously.
As this is not my native language, I hope I have expressed my problem well enough for you to understand.

Thank you in advance!
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Comments

  • blackswan555
    blackswan555 Solar Expert Posts: 246 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Did you commission them correctly ? Are you temp compensating ? When you EQ`d them , did you charge them FULLY first then check SG`s until low cells stop rising ? ( EQ is not a timeable procedure, It is finished when the cells stop rising in relation to each other, SG`s can vary cell to cell depending on levels)


    Commissioning a Battery Bank
    When a bank is first put into service the electrolyte levels and specific gravities
    should be check and recorded. As a battery is charged, water is electrolyzed into
    hydrogen and oxygen gas. Original electrolyte levels should be noted and
    replacement water should be added back to this level.
    The battery bank should be placed on a bulk / absorption charge and voltage
    settings should be set at the maximum level of the above table (30v). This voltage
    should be held for 6 hours and final current, if monitored, should be 2% of the 20
    hour capacity rating. If not the bulk / absorption charge should be continued.

    Have a good one
    Tim

    PS your dealer probably bought them from http://www.barden-uk.com/contact-us.html Give them a ring and ask for tech help ( or email your post) They have a Rolls tech guy there that is very helpfull.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Tim, thank you for your fast reply.
    I do manual temperature compensation concerning charging voltages.
    the SG Readings after the 9 hour EQ are not compensated, the cells certainly warmed up to between 20 und 30 celsius, so there would be no significant compensation. Temperatures here are currently from 5 to 15 celsius, I use to compensate that in my SG readings.
    Your are right about commissioning, I didnt receive have such instructions from my dealer, just let the batteries cycle and doing 2 EQs when there was enough sun.
    Before starting the 9hr EQ the state of charge was >90% (judging from the low current at absorb)

    I certainly didnt pay enough attention to the electrolyte level and its influence on the SG.
    I just measured electrolyte levels in all cells. All are within the limits.
    The good batteries have a very uniform high level.
    The bad batteries have slightly lower levels, the 1.30 SG cell having the lowest level.
    Judging from the cell dimensions, it has 0.2 liters less electrolye than the cell with the highest level. If each cell has 5 liters of electrolyte (calculated from the dry/wet weight difference), this translates into a difference of roughly 1 point (4%).
    Even taking off that point, 1.29 instead of 1.30, Istill find it very high, assuming my calculations are ok.
    I will fill up all cells to the same level and will see what the next EQ says.
    I will have to wait for the sun since my inverter/charger is defective.
    Thank you for your link to barden UK. I will contact them when I am more assured of my observations.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    "I do manual temperature compensation concerning charging voltages."

    i would not advise you doing this as just the action of charging a battery can change its temperature. get yourself a bts and let the controller track the temperature and the proper voltages for charge.
  • blackswan555
    blackswan555 Solar Expert Posts: 246 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    http://www.rollsbattery.com/content/solar-battery-user-manual
    you have to register to get it , but some helpful stuff in there.

    Tim
  • trkarl
    trkarl Solar Expert Posts: 33
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    I have the same batteries as you do and had the exact same problem. My bank is almost 1 yr old. When I got them I commissioned them before I started cycling them.

    I also noticed that three of the batteries have a different type of cap than the other 5 in my 48v bank. Also when they arrived those three had electrolyte to just below the fill well. It was a lot lower in the other batteries but not too low.

    What was weird was that after the first eq those three had the sg rise to 1.300 with two of the cells rising to 1.310 . The others were generally around 1.280 give or take a few points. Two of the other cells got to just above 1.270.

    So I called Surrette to ask a few questions. Basically the tech said not to worry they will even out over time. Well they didn't. I eq every 4 to 6 weeks and make sure the water is to about 1/2 inch below the fill well. I keep records of all eq results and all the cells are usually with about 2 pts of the last eq. I also check during eq and don't stop until the sg quits rising.

    The thing I noticed was all the batteries rose or fell the same number of points during charge or discharge but there was still the disparity between the cells. I am pretty anal about this kind of stuff especially after spending over 6k on a battery bank. The specs say one thing while the batteries say another and this bothers me. a 30 to 40 point spread between the lowest and highest cells in the bank of new batteries is wayyyy too much.

    I called Surrette again and had a long conversation with a tech named Serge. His email is serge@surrette.com. He was very helpful. I found that the date codes on the three batteries were different than the other ones. But it was only off by about 8 months so no big deal. He said that they were probably dry stored and then activated when i ordered them. He said that to dry store them they fill them with electrolyte and fully charge them then remove the electrolyte and wash them out and maybe not all the acid was washed off the plates on those batteries with the high sg. That is what I was told.

    He also said that the ones with the higher acid strength had more capacity than the others, which makes sense but that the higher acid would reduce the effective cycle life by about 5%. He said I could lower the acid and he would give me instructions how to do it.

    Here is a copy of the email he sent me:

    Tim,

    Thanks for the pic. Here is the procedure to lower your SG:

    1-Water all your cell at the proper level.
    2-Place on charge and let rest for at least 2 hours.
    3-Read all SG and not on the included sheet
    4-All cells that are at 1.300 SG do the following:
    4.1-Extract 600ml from the cell
    4.1-Add distilled water (to proper level or 600ml)
    5-Place on charge again, wait 24 hours and re-test and not SG on Test sheet.
    6-Forward me the 2 deferent SG (before and after)

    If you have any question or concerns, please feel free to contact me.




    Serge Bourque, MIT
    Technical Services Manager

    Surrette Battery
    PO Box 2020, 1 Station Road
    Springhill, Nova Scotia
    B0M 1X0
    Canada

    Phone: 1-800-681-9914
    Cell: 1-902-669-1537
    Fax: 1-800-681-9915



    So what I did was I eq'ed the bank again and pulled 300 ml out of each of the 1.300 cells and filled with distilled water. I only did 300 ml because most of the other batteries get to about 1.285 and if these only get to 1.265 after removing electrolyte then the other cells will be different than these. I then took the 1.300 acid and added to the cells that only get to 1.270. Now all my cells are about the same when charging, discharging, and eqing.

    Why there would be such a difference in the batteries when I first bought them I don't understand. It seems to be a quality control problem somewhere along the line but the tech seemed to think it wasn't a big deal. I think it is but like I said I am pretty anal about things like this.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    trkarl, this is extremely helpful.
    This rises a few questions.
    I understand that I have two or three different/possibly linked problems.

    first I dont get the two bad batteries properly charged; after 9 hours of EQ @31V the SGs were still rising.

    Questions here:
    is this normal for commissioning new batteries that have a date code just 3 months before purchase?
    My inverter/charger failed after 9 hours; from what I hear doing EQ with generator is hard on inverters.
    So can a dealer expect you to do a 10hrs+ EQing before starting to cycle?
    Is this a normal selfdischarge, a SG drop from 1.265 to 1.22 in 3 months or less?
    Is there something like a critical selfdischarge depth where batteries are already heavily sulfated and as hard to recover (commission) as my two bad ones?

    The second problem is the abnormal high SG on 1 or 2 cells (probably on more cells when EQed long enough since they didnt stop rising)
    This sounds much like the same problem as trkarl had.
    If I dont even get them EQed with the means of my offgrid system, doing any SG correction myself makes no sense.
    And then, do I as a client really have to mess around with electrolyte?

    The third problem is: why does the SG drop faster in discharge in the bad batteries?
    trkarl says he didnt observe this.
    After the 9hr EQ I had two "zero" rainy days (nothing coming in), the good batteries uniformly dropped by +- 30 points, where the bad ones dropped between 40 (most cells) to 45 (highest SG cell). There is also always a difference in tension.
    For example with the charger set to 28.8V absorb, the two good ones (when multiplied by 4) once had 29.1V where the bad had 28.5V.
    I dont like this at all, especially not with new batteries.

    What can I do more? I think it is justified to ask my dealer to replace them. What do you think?

    @niel: you are right, I will get a bts when things calm down. As long as the batteries behave so differently within the same bank I think compensating temperature manually is a small issue in comparation.
  • hillbilly
    hillbilly Solar Expert Posts: 334 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    I'm reading this with interest as I too have been through a similar process of trying to sort out what is going on inside my batteries (Surrette s-460's) for a while now.
    Just a few off the top of my head thoughts:

    -I assume that you've checked and rechecked all cable connections for a weaker connection, and that your batteries are wired properly so that there is no unequal charging/discharging.
    -Temp compensation could be a bigger factor than you're thinking, I would get the cheap temp sensor pronto.
    -Speaking of temps, is there a chance that some of the cells are nearer to a heat source of some sort, or better insulated than others? This could make a difference.
    -Regarding the uneven charging and discharging of certain cells, that sounds like it could be some degree of sulfation... but hard to say for sure from across the ocean???

    I would be curious to talk with the dealer and ask what they did differently to recharge that first set of batteries. Maybe they are just saying that they were totally fine, but perhaps there is something that they did differently when they recharged them up; it would certainly be worth finding out if there was something distinctly different in their charging system that "worked".
    I have had lots of help from a few different tech guys at Surrette. For the most part they really went out of their way, and asked lots of questions to pick things apart from all angles. The one thing that is kind of frustrating is that it seems that you get some pretty different advice, in terms of hard fast numbers, depending on who you talk to or what web page of theirs you read. For one thing, the tech support guys all favored much longer absorb times than what most of the bullitins on the web say, but even among them there was quite the range of opinions.
    Wish I could tell you more, but there are folks here that are way more informed about the inner workings of batteries than me. Hope things work out for you
    HB
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Thanks for sharing your experience hillbilly. I just read your thread about the s-460, interesting. I am sure the things I learn in this forum will help me to keep my batteries in good shape in the future, but for now I just want to start with a clean bank, I dont think I am asking too much from new batteries.

    I have checked my system several times. Since I only have one banks every cell gets excactly the same charge/discharge current. When I take voltage readings I use the battery poles, so no room here for errors. I also measured the voltage drop in the wiring while charging with high currents, no surprises.
    The batteries are located at the same distance to the wall, the temperatures should be pretty equal.
    Since the other two batteries perform perfectly and uniformly, I really dont think my system has a problem.
    I have sent an email to my dealer asking how exactly he charged the s600 but he wont be back before next monday.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    The moral of the story here is to not buy a battery that is greater then two months from manf. , at worse three months. You have to assume that batteries are not charged since their manf. date. Lead-antimony deep discharge batteries have higher self discharge then the lead-calcium auto/marine/AGM batteries. Three months on a lead-calcium is generally okay.

    I also carry a calibrated pocket DVM and check battery voltage. Never buy if voltage is less then 2.085v per cell ( 12.5 v or 6 cell, 6.26v for 3 cell )

    SG of 1.300 is probably within manf. electrolyte mix tolerance. It does make it more energetic on discharge and slightly sluggish on recharge. It's not really too high.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!
    RCinFLA wrote: »
    The moral of the story here is to not buy a battery that is greater then two months from manf. , at worse three months. You have to assume that batteries are not charged since their manf. date. Lead-antimony deep discharge batteries have higher self discharge then the lead-calcium auto/marine/AGM batteries. Three months on a lead-calcium is generally okay.

    I also carry a calibrated pocket DVM and check battery voltage. Never buy if voltage is less then 2.085v per cell ( 12.5 v or 6 cell, 6.26v for 3 cell )

    SG of 1.300 is probably within manf. electrolyte mix tolerance. It does make it more energetic on discharge and slightly sluggish on recharge. It's not really too high.

    So you agree the 6 batteries (4 S-600, 2 6CS17) I was having problems with must be severely sulfated (most likely because they were sitting too long without being recharged)? My dealer has yet to admit that this could be the case.

    On purchase, all batteries in question had an SG of less or equal 1.235, all had an open-circuit voltage of less then 6.25 per 6V block, so all met your definition of "better dont buy".

    Probably with a long charge and high voltages the 2 bad batteries can be de-sulfated.
    But how about the faster drop of SG? This is what bothers me and makes me really unwilling of keeping the batteries.
    Is this also typical of sulfated cells? Could there be another reason?

    Today after 10 days of cycling/deficit cycling (many cloudy days) I read the following:
    good batteries: all cells dropped by 40/45 points (from 1.270 to 1.225/1.230)
    bad batteries, most cells: dropped by 50/55 points (from 1.265/1.270 to 1.210/1.220)
    bad batteries, highest cell: dropped by 60 points (from 1.300 to 1.240)

    So after almost catching up SG-wise following the 9hr EQ (and one cell going even to 1.30), the effect of the EQ seems to have gone just by cycling a few days. Not surprising the voltages per block also are considerably lower.
    Its just like having two old and two new batteries in a string.

    I am surprised you say an electrolyte SG of 1.30 instead of 1.265 might be within the tolerance.
    I have read the effect of higher SG on live expectancy is quite strong. I have seen the data sheet of a line of solar batteries where they offer either 1.22 or 1.28 filling. They indicate a gain in capacity of 10-15% by the 1.28 electrolyte but a shorter service life of 5 instead of 6 years. I have also seen an experimental study of high SG (1.30 up to 1.40) electrolyte batteries, concluding the capacity gain doesnt weigh out the lower service live. (If somebody is interested I can find the links).
    If I keep the batteries (not very probable) I certainly would try to even out the SG of the cells the way trkarl explained in his post.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Higher SG of 1.300 will reduce battery longevity somewhat.

    Fast drop is SG on discharge would seem to indicate sulfation. It should also be accompanied by lower SG at full charge unless someone has replaced some of the electrolyte with fresh 1.28 SG electrolyte. Sulfation locks up some of the sulphur in lead sulfate crystals on the plates so it is not available to make sulfuric acid from water on recharge.

    Don't overdue equilization as you can accelerate positive grid corrosion and shed lead from plates.

    You might do a load test. Run about 10-20% A-hr discharge for an hour and check voltage and SG. A sulfated battery will show lower SG and voltage. Positive grid corrosion causes higher Rs resulting in fast then normal voltage drop with SG not matching voltage. For a normal cell, cell voltage should be about SG +0.840. For example SG of 1.278 (full charge) + 0.840 = 2.118 which is full charge rested voltage. (6.35 v for 3 cell, 12.71v for six cell battery)

    There is no sure fire way to fix sulfation. Pulse charging can get peak currents up with less negative side effect of equalization positive grid corrosion from oxygen bubble bath. A long 6.70 v slow charge may help for slight sulfation. I have had some success doing several cycles of 10-20% discharge will 20% A-H recharge rate.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    I am still trying to figure out if my batteries, apart from being sulfated and having high SG cells, which can be corrected, are healthy.
    Can you answer me more questions about sulfation?
    I understand that sulfation means part of the sulphur is locked up as cristals on the plates. That means the "full charged" SG is lowered because part of the sulphur simply is not available to return to the electrolye.

    But what is the reason the SG also drops faster on discharge in sulfated cells?
    In my case the probably least sulfated cell, the one with 1.30, dropped most of all cells. (Of course having a lower electrolyte level also should make a slightly faster drop in SG, and this cell had the lowest).
    Thank you for your help, I know I can be somewhat anal (I have learnt the second meaning of this word when trkarl used it in his post and I looked it up in the dictionary, a bit confused about what he wanted to say)
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Sulfation effectively gives you a smaller capacity battery. The sulfate crystals insulate some area of the plates.

    The analogy would be to take a smaller capacity battery and then, on top of this, dillute the electrolyte with water.

    It starts with a lower SG and because of lower capacity it drop more for the original capacity battery expected % discharge A-H extracted.

    I have also observed a lower full charge SG due to grid corrosion. I am not sure of the exact chemical reason but from what I have seen it is usually not as dramatic a drop (1.24-1.25 SG at full charge) as sulfation. It may have something to do with the type of grid alloy used and what it does to SG as by product of its corrosion. I have further degraded a battery thinking it was slight sulfation and doing an equilizing that only makes corrosion worse. Now I do a load test for Rs first.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!
    RCinFLA wrote: »
    You might do a load test. Run about 10-20% A-hr discharge for an hour and check voltage and SG. A sulfated battery will show lower SG and voltage. Positive grid corrosion causes higher Rs resulting in fast then normal voltage drop with SG not matching voltage. For a normal cell, cell voltage should be about SG +0.840. For example SG of 1.278 (full charge) + 0.840 = 2.118 which is full charge rested voltage. (6.35 v for 3 cell, 12.71v for six cell battery)
    The bad batteries seem indeed to have a higher internal resistance (is this what Rs means?).
    For example while discharging with a small 2A load the voltage difference between good and bad 6V blocks is 0.04V, with a 10AH load the difference rises to 0.06V, so there is a higher voltage drop in the bad batteries.
    Wouldnt this be an indicating a higher internal resistance?
    What would you read into this? Is this explained by sulfation alone?

    I can not do a long load test at the moment (short and cloudy days & charger defective).
    I find it is also difficult to do open circuit readings in my running system. I found out that after a heavy charge (charging many AH) even after a night of normal discharge the voltage readings still are higher than to be expected from the SG.
    So I probably could take accurate open circuit readings only after 24hrs without charging and discharging.
  • hillbilly
    hillbilly Solar Expert Posts: 334 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Living off grid, I can understand the difficulty of trying to get accurate open cell readings. I found the following bullitin from Surrette, which I've not been able to find online to provide the link, so I've cut/pasted it partially here. You might find the table at the bottom to be helpful in the future:

    "Open Cell Voltage is determined by taking all the loads off of the battery and letting the battery stand for at least 4 hours before taking a reading. This allows the surface charge to dissipate. To get around this problem either use table 2 or determine the 50% state of charge as described.
    Determining the 50% state of charge Voltage Reading
    Most three steps chargers or inverters monitor the voltage and have an adjustable set point that determines when the batteries are low (50% discharged) and should be charged. Once this set-point is reached the inverter will either sound an alarm or start a generator or tie the battery bank back into to grid power. The voltage set-point maybe factory set but could require verification. Consult your inverter manual for the section on “Cut-off voltage” or “Over discharge protection”. Since the voltage will change depending on whether or not the bank is on load the set point can be determined by a specific gravity reading. A gravity reading of 1.200 is equal to 50% discharged.
    Battery cable lengths, system set-up and other variables can affect the voltage readings as well. Below is a procedure to verify the 50% mark and table 2 gives approximate cut-off voltages at various state of charge. Notice 100% is given as an open cell voltage and all other as under load.
    When using a generator with a low voltage cut-off, set the generator to start at the 50% mark given by table 2 and put the bank into service (11.6 V for a 12V system). When the generator starts-up measure the specific gravity of one cell in the bank. Compare this to the table 1, Specific gravity versus state of charge. If the measured specific gravity indicates the state of charge is more than 50%, decrease the low voltage cut-off setting. Similarly if the specific gravity indicates the state of charge is lower than 50%, increase the low voltage cut-off setting. Note: 50% is the desired depth of discharge but it does not have to be exactly 50%. For practical purposes a range of 45-55% is acceptable. The actual battery voltage corresponding to 50% will change with a change in load. In general, the higher the discharge amperage, the lower the corresponding voltage.
    To determine or verify the 50% voltage set point:
    1. Put all or as many loads as possible on the battery. Disconnect any in coming current inputs such as panels / windmills and grid power. Contact your dealer for specifics.
    2. Take the specific gravity of one cell.
    3. Take another reading 15 minutes and ½ hr later this should give you an indication of how fast the batteries are dropping.
    4. Continue to take readings until 50-55% state of charge is reached according to the specific gravity readings.
    5. Take and record voltage readings (when on load) of any meters to be used for monitoring the state of charge and take a voltage reading across the terminals of one battery.
    6. Compare to table 2.
    7. These readings will then give you a very accurate voltage reading which can be used in the future either as a set point for the inverter or as a day to day monitoring parameter.
    Table 2.
    % Charged/Single Cell/12V/ 24V /48V
    *
    *
    100% 2.10 - 12.60 - 25.20 - 50.40 OPEN CELL
    75% 2.01 - 12.06 - 24.12 - 48.24 UNDER LOAD
    50% 1.93 - 11.58 - 23.16 - 46.32 UNDER LOAD
    25% 1.84 - 11.04 - 22.08 - 44.16 UNDER LOAD
    0% 1.75 - 10.50 - 21.00 - 42.00 UNDER LOAD

    Note: This will give you a very good idea on how your battery bank will behave and how long it will last with no power inputs. New batteries will give about 75% of the specified capacity until the battery has been cycled 40-60 times (1-3 months of service)."

    HTH,
    HB
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!
    hillbilly wrote: »
    Living off grid, I can understand the difficulty of trying to get accurate open cell readings. I found the following bullitin from Surrette, which I've not been able to find online to provide the link, so I've cut/pasted it partially here. HB

    That link is from the Rolls - Products - Renewable Energy - FAQ's - Voltages, Specific Gravity and State of Charge, the actual link address is:
    http://www.rollsbattery.com/content/renewable-energy-bulletins-solar-wind?q=node/51&phpMyAdmin=2eda4dec0bd69647b9e3cf0f71e01d23&phpMyAdmin=9dec4a269d70t7a63be7c
  • hillbilly
    hillbilly Solar Expert Posts: 334 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Cheers, that's it. Thanks, that's probably a much easier read than my sloppy cut/paste job here.
  • maok
    maok Registered Users Posts: 20
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Hi,

    I carefully read your posts, and I noticed, I have the same problem with one month new batteries Rolls S-530.

    so at the end, you think is this a positive grid corrosion or sulfation?

    if it is corrosion, the end of battery life is close. so maybe I should return the batteries?

    thanks for reaction

    Maok
  • maok
    maok Registered Users Posts: 20
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    ...the voltage drops much faster than the SG. and the diference between low cell and high cell is 3 points on hydrometer. it is a lot..
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    I do not have much experience, thats why I am asking so many questions myself, but since you have provided little data I can ask you the same questions I found helpful.

    What a date code do your batteries have?
    What was the SG of your batteries on purchase? (Block Voltage?)
    Did you do a full charge and an EQ initially?
    Are the electrolyte levels fairly equal? the SG readings for the same cell can differ considerably between near minimum and near maximum level. Also, after adding water there is not much use taking readings before after the next EQ.
    3 points (or 30? still not sure if a point usually is 0.01 or 0.001) is certainly too much for new batteries, in my good ones its even hard to find a difference of 0.5 points in any state of charge.
    When you talk about voltage drop do you distinguish between (almost) instant drop resulting from load current and internal resistance of the battery, and the voltage drop as a result of the battery being more discharged?

    For me its a big advantage to have 2 healthy batteries in the string for comparison.
    Unless somebody puts new labels on old batteries I can not imagine that your (and my) batteries are already heavily corroded.
    RCAinFLA said frequent EQ will accelerate corrosion, but shouldnt corrosion be no problem with a few month old batteries, almost uncycled and designed for 10 or 15 years life?

    I still unsure how to interpret the symptoms of my own 2 bad batteries.
    Again, my symptoms are:
    - lower average SG on full charge; catching up only after very long EQ, then losing ground again quickly.
    - considerably faster drop of SG on discharge
    - lower voltage per cell on charge AND on discharge
    - higher voltage drop when putting on a load.
    Is this all explained by sulfation alone?

    I always thought when there are batteries with different internal resistance in a string the batteries with the higher resistance should have a higher voltage while charging and a lower while discharging.
    Is this wrong?
  • maok
    maok Registered Users Posts: 20
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Hi,

    thanks for your answer.

    I hope, nobody changed the label on battery:cry:. so thats why the corosion is out of question?

    at first, I didnt measur the SG, when batteries was new. Just after two days and only in one cell. It was mistake, I didn know about these problems with batteries.
    and SG was around 1,270. Voltage was high. for shure it was over 12,6 V in two bat. in series. /I have two S-530 in series/.
    but then about three days load around 5A without charging and after this moment I never more get SG to green field./over 1,250/

    Maybe It could be slow charging? I have charger, which can give to bat only 20A, and it is maybe not enough for 500Ah battery.

    yesterday I filled watter, that all cells are equal. than I equalized around 8 hours on 15,5V and then on 16V at 15 amps, and SG is now from 1,250 to 1,215. isnt it strange for new batteries?

    And has anybody experiences with a desulfator? /high voltage impulsesto battery/
    maybe I should use this ..

    thank for all reactions..
    Maok
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Do any of you guys have Battery Monitors (or equvalent) to measure the current and Amp*Hours you are running through the batteries during charging/loading?

    If you have parallel strings, is the wiring all equal length and tight connections? Have you used a DC amp meter to ensure that all strings are properly sharing the current?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Only statement that you keep saying that is strange is SG drops fast on discharge. You are not quantifying these statements with numbers that say what A-H's you have taken out of the battery. This would normally indicate sulfation.

    If you discharge a battery 30% of its A-H rating then after the battery has rested for a couple of hours (chemical equilibrium) the SG should match the 70% SoC level (1.217). If it drops more then battery capacity predicted, then probably indicates sulfation.

    On the topic of equilization:

    Positive plate is 'formed' with a coating of Lead dioxide. This is what is converted to lead sulfate on the positive plate during discharge. Lead dioxide it not a good conductor so too much on the positive plate will increase battery Rs.

    In today's battery manufacturing, the positive plates are usually pre- 'formed' before the battery is assembled. This means no assembled battery forming charge is required after electrolyte is added. It speeds and simplifies the manf. process.

    The positive plate after it is pasted and dried is primarily lead with some small amounts of additives. It is the charge forming that makes it the positive plate. Again this is the coating of lead dioxide. The old way was to charge the assembled battery to give the positive plate the lead dioxide coating. This gave the original name of 'storage battery' as energy had to be initially put into the battery so it was 'stored', not created from battery construction material like a zinc dry cell battery.

    Many manufactures state that the battery will not give full capacity until it is partially cycled a few times. Part of the reason is because the pre-forming has not built an optimum coating of lead dioxide. True dry charge batteries, where no electrolyte is installed yet, typically do not have pre-formed positive plates.

    From the point the positive plate is formed with lead dioxide it is starts its finite lifetime. As the battery is used and ages, more and more of the base lead and grid structure of the positive plate is converted to lead dioxide. This process is irreversible. Some of it drops off and falls to bottom of battery. This is why positive plates are typically made thicker then negative plates.

    Equalization accelerates the creation of lead dioxide and oxidation of positive grid. Every equalization takes some of the finite lifetime from the battery.

    Self discharge primary occurs on the negative plate. Float voltage of 13.4-13.8 vdc (for a 6 cell battery) is a compromise between keeping the negative plate charged and avoiding too much oxidation of the positive plate.

    I wanted to make the point on equilization since many of threads in the forum leave the impression that equilization is the cure all to fixing a troubled battery.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    I agree with RC about equalization... It is not a cure all and by itself causes significant damage to batteries and should only be done when conditions indicate (something like once a month, not every few days to "fix" problems).

    There are usually other factors that are causing problems. Measuring voltage / amps / amp*hours / current sharing with a DC clamp meter / Specific Gravity, Temperature, etc. while resting / under load / under charge are all important to understand what is happening to the battery bank.

    I would not assume as first guess that there is "something wrong" with the battery bank--I would suspect "operator error" first.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    There is little written about SG degradation reasons other then sulfation.

    I think part of the reasons may be additives put into the plates. If they are ejected out prematurely due to overcharging they might be some of the reasons for SG changes. Since there is so many different additives by different manufacturers, there is no single answer. This is only speculation on my part.

    Obviously contaminates, like putting in tap water, could have an impact.
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    RCAinFLA,
    this is very interesting. I have already asked myself what "precharged dry" means and was surprised when an earlier poster said they put electrolyte, charge and then remove it for storage. Following your informations I certainly will overcharge less in the future.
    One thing I noted is that with standard absorb times/voltages (3 hours/28.8V) even the 2 healthy batteries will never go beyond SG 1.24/1.25, only an 3hr EQ brings them to their nominal SG. Of course the days currently are short and so is the time available for charge.
    Other types of wet batteries that are more common here (OPzs and others) seem to show nominal SG with a lot less overcharge.
    So is it sufficient to "see" the nominal SG of 1.265 or more only every 2 or 3 months, assuming that with SG 1.24/1.25 they are sufficiently charged to avoid sulfation?

    I thought I already had quantified the difference between my healthy batteries and my bad ones by noting that in the same time the healthy ones from full charge dropped by average 30 points (should be a 20% discharge) the bad ones dropped by average 40 points, 33% faster. (the good and the bad batteries are in the same string thus always charging/discharging the same current).

    BB,
    your questions seem to be aimed more at Maok, since I already answered most of them.
    I have an off grid system for 12 years now and killed my first batteries by deficit cycling, I did the classical beginners error of underestimating loads/losses and overestimating charges. Since then I seem to treat my batteries well. I do use current clamp and DVM regularly to check my system.
    Battery monitors are not common here, in fact I dont know anyone that has one and dont even know if I can buy them here.

    I am not sure if you have read my posts when you suspect an "operator error".
    What would your explanation be that only the 2 batteries that were much more discharged on purchase have a problem, while the 2 others in the same string are perfect? I have the batteries for only 7 weeks now and had the problem from day 1. I know that most batteries problems are resulting from bad treatment. I would say I haven't had the time yet to treat them badly.

    Maok,
    there is still al lot information missing about your system: what is your charging source, charge conroller, how do you cycle your batteries? (Probably you should open your own thread, it would be easier to follow)
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    mbzebro,

    There are two or three sets of questions going on here... So it was a general question.

    12 years on a set of batteries (depending on brand/model/usage) is probably not bad at all.

    The battery monitor (cumaltive Amp*Hour meter/etc.)--from my point of view--is a very handy way to see the general state of charge at a quick glance without the specific gravity measuring or waiting/guessing at rest voltages. As well as making it easier to spot the deficit charging problems.

    A battery monitor is not perfect... Amp*Hour capacity of the battery bank is assumed, and the monitors generally use an algorithm to determine when the battery is "really charged" (high voltage, low charging current, etc.) to "reset" back to 100% capacity (whatever that is for a given battery bank over time).

    I know that you can find Battery Monitors in the UK shops (sorry, I don't know about Portugal).

    Perhaps Nigel (Nigtomdaw), a UK Expat in Spain can help (I think he does local Solar RE sales and installs too). Perhaps you can send him a Private Message -- if he does not see this posting.

    The question about differences between batteries... In your case, I believe you have one series string (4x 6 volt)--so there is no current sharing issue.

    In that case--I would agree that in your case, you have much less that can go wrong assuming that all batteries where brought to full charge at least once in recent history.

    I am sorry--I was not taking aim that everyone (including you) are responsible for their battery's ills... It was more of a reminder to check the possibilities of other issues before questioning the batteries themselves.

    Even though batteries are a pretty well known manufacturing quantity now-a-days--there are still things that can go wrong in manufacturing and distribution.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    With regards to battery monitors available in Europe, you can find products from:
    - Victron energy
    - Smartgauge.co.uk
    - www.studer-inno.com
    - and Xantrex
  • mbzebro
    mbzebro Registered Users Posts: 18
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Bill,
    thanks for explaining your post.
    I agree that one can make many mistakes with batteries, I certainly did with my first set 12 years ago (They lasted only 2 years, not 12 years).
    As I had little money to spend at the time I replaced them for 2nd hand standby-type AGMs that were very cheap.
    They did surprisingly well and were over 9 years old when I decided to replace them with the surrettes, expecting to be out of trouble for the next 10 years or so.
    What happens is that I am spending a lot of time checking my system (also spent on gas for the generator, battery transports, a inverter/charger repair that has yet to be done).

    I certainly reacted a bit frustrated to your post because it reminded me of my dealers reaction, sorry for that.
    A lot of people in my region are rather sloppy concerning battery maintenance; they typically have small off grid systems and tend to expect charge controller and inverter to do the whole job. Some of them dont use generators and cycle in the 0-50% SOC range during most of the winter; not surprising they buy new batteries quite frequently.

    That is problably one reason I have a hard job convincing my dealer that my case is different and that I know what I am talking about when I say I know the charging basics and I really checked everything.
    I expect to talk to him this week equipped with some extra informations from this forum, thank you all for this.

    Thanks stephendv for the infos about battery monitor sources, I am considering buying one.
  • hillbilly
    hillbilly Solar Expert Posts: 334 ✭✭
    Re: weird battery problems with Rolls Surrette batteries, SG up to 1.30!

    Just wondering how you're coming to some conclusions without a battery monitor. For instance you mentioned in the first post that you use about 60AH a day, and what you're looking at to decide when the batteries are "charged"?

    I would also recommend a battery monitor, although probably less so to someone who is experienced with their batteries and has a good sense of what to expect from them from past experiences. They are extremely helpful as an additional source of data, I kind of use mine as both a quick glance of SOC, Voltage, and discharging current to see if all of those numbers "agree". If all the numbers add up to what I think they should then I tend to trust the SOC reading and assume that it's "business as usual" with the batteries; if something seems out of line between any of those numbers then I go get a second opinion from the hydrometer. I also randomly (my wife says obsessively) check the SG readings from a couple of cells and then compare that to what the meter readings are saying, just to have a base of comparison so that I can see what my monitor readings tend to correlate to.

    The reason that I mention all this is that I think that in some ways a battery monitor can get you into some trouble if you don't periodically reconcile it's readings with actual SG level readings to ensure that you're getting an accurate assessment of the SOC. I've also found that it takes some time to get a sense of how to judge voltage levels by comparing them with charging/discharging currents. Overall battery monitors are just another really handy tool to have at your disposal for checking in on the operation of your system; no more, no less.

    BTW, good luck with your struggles, and did the dealer ever tell you any pertinent info on how they managed to charge that set of batteries?

    HB