Sulfated beyond hope?

pedro65pedro65 Registered Users Posts: 21
I recently purchased an off grid home. The battery bank is 16 S-460 Surrettes. They have been running down too quickly overnight, the voltage dropping to 49.2 from a full charge even with the inverter turned off and no draw on the ban.

The batteries themselves are less than two years old, and supposedly cared for properly with regular EQ. I don't know how they were put into service though. They were being EQ'd at about 61V for a couple of hours once a month.

Yesterday, based on information from Surrette, I EQ'd them at about 64V. The sun wasn't out, so I used my genset. I was able to keep the voltage up at 64 for a couple of hours, but then couldn't get the voltage to stay that high., it was probably around 63 or so.

I was following the sp gr closely in a few of the cells. I was unable to get the gravity up in any of them starting from full charge. I was probably only getting 1.24 at tops. During the EQ, the electrolyte was literally turning black from the sulfate.

In the end, I probably EQ'd for 5.5 hours without seeing an appreciable rise in the SG. I haven't had a chance to check and see whether or not they are performing better or not (it is a vacation house..)

Are these batteries toast? Or do I need more EQ? I read the other two threads about SG variation in the Surrettes, but I can't seem to find an answer there....

Thanks
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Comments

  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    Batteries must be fully charged before commencing EQ, your`s do not sound like they are, What temp are they and do you have/use temp compensation ? please list your equipment & location,/ fill profile in

    Tim
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    Hello pedro65,

    Well, EQing at 61 Volts seems too low to me, unless the battery temp is high.

    Probably the reason that the EQ voltage drops after a long EQ procedure is that EQing warms the battery, which reduces the terminal voltage, and the apparent impedance of the battery.

    It is important to watch the SGs of one or two cells during EQ (as you are doing), as well as the temeprature of the electrolyte in several cells as well. In the past, Surrette recommended to never allow the electrolyte temp to rise above 115 degrees F during this process. At this point, the Surrette battery manual states that EQ should be between 62 and 64 Volts (nonimal). Altho they do not state this, in my opinion, this value needs to be temperature compensated. Ideally, your charger that you are using for the EQ should maintain this EQ voltage constantly. Many chargers seem to not temp compensate EQ voltage, and I do this manually for each EQ. I hope that your charging system (may be a part of an inverter) uses a Battery Temp Sensor -- BTS. This helps maintain the charge/EQ voltage during normal charge and EQ cycles.

    Furthermore, it is very important to use a high quality Hygrometer to measure the SGs. For example, the host of this site sells several quality glass type hygrometers which are accurate, and also electrolyte thermometers which elinimate the guess work when measuring the SGs. As the electrolyte temp rises, the indicated SG goes down. So depending upon this temp, the SGs during EQ may not really be as low as you are reading. There are also temperature-compensated hygrometers (altho, I've never used them).

    I do not like the sound of the black color in the electrolyte, but this may not be uncommon in your situation -- I dunno.

    Contacting Surrette on Monday, may help get some pertenant info on your situation. Surrette has excellent technical support.

    Enough for now, Good Luck, and let us know how you are progressing. 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.
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    They were "fully charged" based on voltage. They are temp compensated through the inverter/charger (outback)

    These are in Flagstaff, using 12 Sunmodule 175 panels for a sunny day and a backup genset, propane powered 10KW.

    I am a rank newbie, but have been educating myself along the way. The problem is that with no experience, it is hard to tell whether the system is working the way it is supposed to or not. At this point, I have a system that should be able to support 8Kwh overnight, but it runs down to 65% even with no current draw.

    My current settings have been to charge at 58.8v with a float at 54v. From some of the things I have read, it may be that the previous owner was doing this, with regular "EQ's" at only 61v. I am guessing that this battery bank may have been kept in a perpetual state of partial charge and is heavily sulfated.
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    Hi again Pedro65,

    Well, seems to me that you are doing very well so far.

    Thanks for the additional info, so, I guess that the temp comp through the inverter/charger is via a BTS ? This is good, especially in your climate.

    If you do not have it, request the Battery Manual from Surrette, it is a download via e-mail request.

    I would continue to EQ, while watching the electrolyte level, SGs and temps during the process. Think that you are in the 'Corrective EQ' territory. If you watch the above three parameters during the process, it seems that you have little to loose, other than a bit of fuel. It is worth the effort. Please try contacting Surrette, if you have not, as they can shed additional light on this subject. Good luck, and please let us know how you are doing. 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.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    Any idea what firmware version your mate is ? I am not sure which , but I believe the earlier versions did not temp compensate on EQ ? I will ask on OB forums,

    How many inverters do you have ?

    Tim
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    Thanks all!
    It has been surprising to me how difficult it has been to get answers to my questions from local experts. I think this is just all so new, there are few who have a really deep understanding of these systems from personal experience. This site really seems to concentrate the people with real world knowledge of these types of systems!

    I don't know the firmware on my Outback....I was doing a bit of "manual" temperature checking, ie. "manually" (my hand!) checking the temp on the side of the battery and the hygrometer as I filled it. The Mate gave me a temp of about 107 after all the EQ time. But even if you assume .003 decrease in SG per 10 degrees above 80, it still seems low. Now I did not let the batteries sit for a while after I did the EQ, so perhaps more of the sulfate will get back into solution?

    Vic I was following the "corrective" EQ suggestions from the manual as you suggested. I had hoped that after a few hours I would see a significant rise in the SG. I didn't, and of more concern, I was never able to get the sg's in the different cells very close to each other. I thought it promising that the amps increased, and the voltage decreased after a few hours, but I never saw a corresponding rise in spec grav.

    I think I am going to head up on a sunny day when I can get the panels to do the work. With the sun exposure, snow and altitude, they can really pump out the amps on a sunny day. I am hoping that I can do another long EQ at high current to continue my progress. I will definitely contact Surrette as well, to see if the turbid electrolyte is a good sign or a bad one!

    Thanks again.....
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Sulfated beyond hope?

    I have only seen the electrolyte turn dark from overcharging.
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    OK pedro65,

    Well, my MX-60s do NOT temp comp EQ Voltage, and they have the latest FW -- 5.11.

    Think that there is a reluctance by manufacturers to temp comp Veq (in inverters and CCs), as it could cause an inverter to Hi Volt shutdown if the battery temp is low, and this is escpecially bad for unattended systems and automatic EQ. This is just a guess on my part.

    Sounds like you have a good plan. Getting an electrolyte thermometer may not be a bad idea, as the temp affects Veq and SG readings. I am a bit too sensitive to this issue just now, as my temp comp from the Xantrex inverters is not exactly correct, but it is more of a minor issue. Perhaps am obsessing too much on this, and missing a much more important (and unknown to me) issue.

    Good Luck, but seems that you are on a good course for now. 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.
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    I think that is essentially what EQ is, a controlled overcharging. What I am hoping is that the precipitate is coming off the lead and will go back into solution.....
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    Given that ambient temps were in the 30's, and the room the batteries were in was in mid 40's, I am hoping that the a true overtemp would be difficult.

    I think it may be more important to get an accurate temperature for getting the "true" spec grav if using that to judge the absolute charge of a cell.

    For my purpose, I was hoping to see that all the cells were at a similar spec grav, relative to one another, regardless of the temperature compensation.

    In any case, I appreciate all the support from people who have have been doing a whole lot longer than I!

    I will update the thread as I get more data.....

    P
  • BB.BB. Super Moderators, Administrators Posts: 29,981 admin
    Re: Sulfated beyond hope?

    I am going to bet that black stuff in the electrolyte is bad news..

    So--First I would start working on the warranty and see if it applies.
    SERIES 4000Failure within 24 months from the date placed in service yields FREE REPLACEMENT, not including freight charges from the factory to the applicable destination. After the first 24 months of service, defective batteries will be adjusted for a period of up to 84 months prorated from the date first in service at prices in effect at time of adjustment.
    To claim a manufacturing warranty, proof of purchase must be presented, showing the date of purchase and the battery's serial number. The battery must be tested by an Authorized Battery Outlet for actual defect, and upon confirmation of the defect, the warranty will be administered.

    The Warranty does not cover shipping damage, cracked covers, cracked cases, bulged cases from heat, freezing or explosion, discharged batteries, the use of undersized batteries damaged from electrical equipment. This warranty covers only manufacturing defects.

    The Company makes no warranty with respect to its batteries other than the warranty stated above. All implied warranties of merchantability and all expressed and implied warranties of any other kind are hereby excluded.
    Next, I would question the design load... It seems a little small for an 8kWH per night load... A S-460 is a 350 AH 6 volt battery at 20 hour rate.
    • 350 AH * 16 batteries * 6 volts = 33,600 WH = 33.6 kWH
    • 33.6 kWH / 8 kWH per night = 4.2 days of storage
    Normally we recommend:
    • 3 days of no-sun * 1/50% max discharge = 6x daily usage
    Assuming an 8kWH per night load, that will take you down to 75% the first day, and ~50% the second day.
    • 12 Sunmodule 175 panels in Flagstaff Az.
    Using the PVWatts website; 12x175w=2.1kW of panels; use 0.52 for off-grid battery based derating, flagstaff:
    "Station Identification"
    "City:","Flagstaff"
    "State:","Arizona"
    "Lat (deg N):", 35.13
    "Long (deg W):", 111.67
    "Elev (m): ", 2135
    "PV System Specifications"
    "DC Rating:"," 2.1 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 1.1 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 35.1"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 8.5 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 5.19, 176, 14.96
    2, 5.92, 180, 15.30
    3, 6.27, 208, 17.68
    4, 6.44, 202, 17.17
    5, 6.56, 207, 17.59
    6, 6.61, 194, 16.49
    7, 5.95, 178, 15.13
    8, 5.54, 166, 14.11
    9, 6.59, 198, 16.83
    10, 6.19, 195, 16.57
    11, 5.47, 175, 14.88
    12, 5.07, 172, 14.62
    "Year", 5.98, 2251, 191.34
    8kW hours of AC power a day is ~240 kWhrs per month... From the PV Watts program, you are generating ~180 kWhrs per month (20 year average weather) for February.
    • (240-180)kWHr per month / 30 days = 2 kWhrs per day deficit
    What is the Amperage rating on the battery charger (from genset). And do you know how much current (amps and hours) it is putting back into the bank when you run it?

    And what is your bank voltage (probably 48 VDC?)?

    Also, do you have anything like a Battery Monitor to check the Amp*Hours consumed vs Amp*Hours replaced?

    I am guessing the bank was not being kept above 75% state of charge--and was allowed to drift down below that (and below 50% state of charge) for long periods of time--Leading to sulfate hardening. Coupled with an undersized bank, undersized solar array, and/or not enough generator use (every other day, if not daily).

    -Bill

    PS: I reread the 8kWH statement--and this is probably not your average load--anyway, the numbers are there for you to plug in your numbers.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    Thanks for all the data Bill. You are correct, I don't think we use nearly 8kwh. I don't have a monitor, but I think that is my next purchase.....I am fairly sure that the people I purchased the house from ran these batteries way down pretty regularly too.

    I do believe that the batteries are all in warranty, the problem is having 16 120lb batteries tested by an "Authorized battery outlet"! The house is 3 miles out a forest service road, and then up a 50 yard hill to a vehicle. I would love to have the batteries load tested so that I can see if they are still within warranty.

    Any suggestions? Are there mobile "authorized battery outlet" guys out there?
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    Do you know if the settings in the MX, (absorb voltage and time) have been altered from default ? what are they ? but I would say your batteries are undercharged as they are now,
    I presume you only have 1 inverter ? if so that is 45amps of charge from it, your batteries are 700ah, so even if you said 50% dod then the charger at full power all the way, that would be 8 hours, in reality, you will be lucky to see 40amps at higher voltages and their current draw drops off as they charge, so can be a lot longer,
    Batteries need to be fully charged before commencing EQ (or you get what you got, they still need charge, so try to draw more current, your charge source was not big enough to provide it, so V dropped)

    The first thing I would try, would be a long 10hr ish absorb at the top of ab v 60v (temp comp that, 48v system, if bats hit 45c shut down and rest) if you have a clamp meter it is worth keeping an eye on the charge current also, toward the end of the charge it should drop to around 14 ish amps, check SG`s after, I think you will find they have come up :D then time for EQ

    Have a good one
    Tim
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Sulfated beyond hope?

    it doesn't sound good for those batteries and i am assuming too that the electrolyte levels are proper filled. they sound as if on their last legs and you should try the warranty to get replacements. if they were cycled too deeply and too often this could be the problem. if they see the batteries as abused they may or may not honor the warranty, but this is usually something they would determine, somehow?
    they may not do house calls, but if you take a few of the batteries to them so they can do a preliminary evaluation on them as an indicator of the general state of condition for the rest of them. if no good then retrieve the rest if they'll replace them.
  • PhotowhitPhotowhit Solar Expert Posts: 5,077 ✭✭✭✭
    Re: Sulfated beyond hope?

    OK, I'm late to this discussion, and admit to skimming through, that said...

    "overnight, the voltage dropping to 49.2"

    Is this with a load on it? without a load? with out a load and letting settle for 3-4 hours?

    With a substancal load your battery might be nearly full, and with any load and no charging I'd guess close to 80% full (by voltage)

    I alude to this voltage evaluation since I read about the "black stuff" and I think that might be a battery additive (like thermoil) that creates a liquid cap that reduces out gassing and hence maintanance, adding water.

    Worth looking into, check with the former owners if you can.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Sulfated beyond hope?

    that additive is a good possibility and could possibly void any warranty right there. people sometimes do desperate things to save their batteries after being abused. (i am assuming previous owners did this and not you) who knows as they may have added something that could very well have killed the capacity.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    The "black" is probably a result of a little plate shedding, it is the lead (oxide ?), It normally sits at the bottom of the bat (you can see it on transparent case bats) when you EQ , it stirs it up.

    Tim
  • BB.BB. Super Moderators, Administrators Posts: 29,981 admin
    Re: Sulfated beyond hope?
    pedro65 wrote: »
    The battery bank is 16 S-460 Surrettes. They have been running down too quickly overnight, the voltage dropping to 49.2 from a full charge even with the inverter turned off and no draw on the bank.

    The batteries themselves are less than two years old, and supposedly cared for properly with regular EQ.
    ...
    I was following the sp gr closely in a few of the cells. I was unable to get the gravity up in any of them starting from full charge. I was probably only getting 1.24 at tops. During the EQ, the electrolyte was literally turning black from the sulfate.
    There is some sort of self discharging/lack of charging due to sulfates... My two cents guess.

    Kind of goes to the heart of the matter why solar RE systems may not have much value when a property is sold... Old hardware and unknown treatment of battery banks, etc. Makes it difficult to really assign much value to the installation.

    Sort of like buying a used car...

    -Bill

    PS: Could also be damage from over charging / over equalization... Ideally, only do equalization when the cells are out of balance (Trojan recommends SG differences is 0.030 or greater)...

    And, from this thread, you are not alone in trying to figure out how to optimize battery bank charging.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Sulfated beyond hope?

    blackswan555,
    maybe and maybe not as we aren't there to know for sure. they need evaluated in person by qualified battery experts.
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    Regarding shedding, Surrette seems proud of their enveloped plates, feeling that the envelope retains the sluffed plate material, allowing more room in the jar for plate material and electrolyte. Perhaps some of the lighter (smaller particle) dross tends to float about until it is either combined or perhaps sinks (?). Do not recall if the S- 460 has such envelopes, tho.

    Have not seen this black material floating in my batteries, but there seems to be a small amount of grey material on the diffuser at the top of some cells. I believe that purging electrolyte from the hygrometer may blast this material off the diffuser -- another guess on my part.

    I still wish that Surrette, or some other large battery manufacturer would host a Forum similar to this, but guess that there are soooooo many variables and perhaps opinions that such site might just be NOISE. Am done guessing for now, 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.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    I look after 5 sets of rolls & 3 sets of "transparent`s" I see it to a varying degree on all but the less than 9 months/ 60 cycles old set during EQ,

    My guess is that the OB equipment has been mainly left at default`s, which is an absorb for 1 hour, far to short causing undercharging, the EQ`s that have been performed, were not done properly,
    I think a good long absorb until sg`s do stop rising , then an EQ, again till sg`s stop rising, Will get them back, if not, you need to do the above before commencing corrective EQ anyway.

    Have a good one
    Tim
  • PhotowhitPhotowhit Solar Expert Posts: 5,077 ✭✭✭✭
    Re: Sulfated beyond hope?

    Just for the record, as an additive I dont put thermoil in the same catagory as EDTA, I think it isn't uncommon in forklift batteries that are deep discharged often, just not needed in solar apps.

    I've been looking at forklift batteries and have seen this in used batteries. I'm also close to St Louis where Stabb batteries is a major player and promote it's use.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    Just to add, some background on my reasoning, below from Rolls
    Equalization - Corrective

    Corrective equalization needs to be performed if symptoms arise such as a constantly running generator (low capacity) or the battery bank will “not hold a charge”. These symptoms are typical of a heavily sulfated battery. If a battery is not being fully charged on a regular basis or limited equalization is performed using a generator (see Bulletin 611, Generators, Inverters and Equalization) sulfation will occur from “deficit” cycling. This undercharge condition can take months before it becomes a major and noticeable problem. This under charge condition is caused when batteries are deficit cycled. The bank receives less of a charge each cycle and starts to sulfate. Eventually the sulfate will cause a resistance to charge and a “false high voltage” reading will occur. The “false high voltage” is measured by the charge controller, which further lowers the charging current to maintain the voltage set point. This further increases the undercharge condition. This is one reason why specific gravity measurements are so important as “false high voltage” readings can be misleading. See Bulletin 609, Voltage, SG and State of Charge for information on how to correctly interpret voltage readings.
    my reasoning on undercharge and not severe sulphate, The OP mentioned the V dropping when trying to eq, I am supposing the bats are trying to draw more than the inv can provide ?, that is not the symptoms described above, more of a sign of in need of charge,

    Tim
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    When I manually EQ my 12 V banks of S-530's (this is using a Variac/ tranformer/rectifier), The Icharge diminishes, Vbat rises for quite some time, flattens out, and then falls progresively after more than an hour. I've assigned this to the the battery temperature rising, causing voltage depression. This is the thing that causes thermal runaway in systems that do not compensate Vcharge/EQ for changes in temp, IMHO.

    Blackswan, re the battery voltage dropping during EQ, this may be caused by insufficient charge current capability, BUT normally, the Icharge/Ieq diminishes during normal charge/EQ cycles, if the voltages are compesated. I have never EQed via generator/inverter/charger, so I do not really know if the EQ voltage from inverter/chargers is normally compensated, and in any case, mine are brand X.

    OK Pedro, good luck, but it seems to me that the attention you are giving your system is by far more attention than has ever been devoted to it, so this is a good thing ! Many, many of my neighbors (off-grid) pay NO attention whatsoever to their systems until the lights go out. 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.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?
    Blackswan, re the battery voltage dropping during EQ, this may be caused by insufficient charge current capability, BUT normally, the Icharge/Ieq diminishes during normal charge/EQ cycles, if the voltages are compesated. I have never EQed via generator/inverter/charger, so I do not really know if the EQ voltage from inverter/chargers is normally compensated, and in any case, mine are brand X.
    I agree, the amps should be falling IF the batteries were fully charged in the first place, The batteries "want" more charge than the inv can supply (about 40 amps) which they would not if severely sulfated. Pointing to bat`s not charged enough to commence EQ
    Inverters are temp compensated on EQ,

    Tim
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    Photowhit....that was the voltage with the inverter circuit breaker thrown and all loads off the bank....

    I will check the settings for the PV inverter regarding charge times....anyone want to give a good set of "gouge" numbers for a 16 batt. bank of S460's in a 48V system?

    With the amount of snow we have been getting in Northern AZ, I am sure it is a challenge to get enough juice to the system. I will probably increase the charge voltage and time to at least take advantage of our very sunny days, when we get them. Unfortunately I am only at the house intermittently, so it is a real challenge to stay on top of this stuff.

    I have some concerns about burning out the inverter, as I have heard that long EQ's on the genset can be a problem as well.

    I totally agree with you BB regarding the buyer beware. I was told that everything was in tip top shape, only a year and a half old....but I have found that almost no one that I have spoken to has nearly the understanding of these systems that this forum seems to have! I suspect few people know enough to recognize what questions to ask......

    thanks again all.....If I can't save this bank, it won't be due to lack of attention!
  • VicVic Solar Expert Posts: 2,984 ✭✭✭✭
    Re: Sulfated beyond hope?

    OK, agree that in Bulk, the Icharge is limited(mostly) by the current capability of the charge source, but once the Vasorb is reached, the Icharge diminishes during the Asorb cycle. An EQ is just a Bulk/Asorb cycle at a higher voltage, so, once Veq is reached, the current diminishes during this cycle as well. All of this assumes that one is only looking at charging currents into the batteries -- ie excludes downstream loads on the batteries. If charge/EQ coltages are not compensated, I think that battery voltage can decrease during EQ, and this causes the EQ current to rise, at least in my experience.

    Think that we are getting to the very fine points, and are perhaps onto the same page, or at least in the same chapter. Thanks 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.
  • pedro65pedro65 Registered Users Posts: 21
    Re: Sulfated beyond hope?

    Blackswan that would be great news for me, an undercharged bank I think I can fix.

    Unfortunately my physics is circa 1988 pre med classes, so I have been trying to bone up using a lot of the threads here.....I don't recall my inverter showing anywhere near 40 amps when the genset was charging....probably more along the lines of 15amps......is that the problem, not enough current?

    If the bank was "undercharged" why am I seeing a 51.9v or so in the afternoon after the sun is off the PV cells? Shouldn't the voltage drop precipitously once the charge current is gone if they are not fully charged? My charge controller was showing over 200 minutes of "float" time in the previous 5 days to my starting the EQ, I assumed that meant that the system was "full up"....
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?

    do you normally throw the inverter or any other breakers before leaving ?
    What panels do you have ? W ?, insolation ?

    What loads are used , How long / often , ?


    Rolls recommend 2 hr absorb for yours (4000 series ?) there may be different strategy`s depending on usage,

    Have a good one
    Tim
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Sulfated beyond hope?
    My charge controller was showing over 200 minutes of "float" time in the previous 5 days to my starting the EQ, I assumed that meant that the system was "full up"....

    The charge sequence is first bulk, all the amps the panels can provide to push the bat voltage up to the absorb voltage setting, when it reaches ab v, it is then timed (one hour by default) the amps the batteries "pull" will fall with charge, 1 hr later as long as the voltage has stayed @ ab v, It go`s to float, you need more time on there, depending on your usage and loadings, you may be able to increase that even more and cut down on EQ,

    Tim
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