Low rest voltage on GNB absolyte IIP cells

Dapdan
Dapdan Solar Expert Posts: 330 ✭✭
Hi all,

I am brand new to your site. I am not totally new to RE. I have recently acquired some GNB absolyte IIP agm cells ((100A-19). i have charged them up and max cell voltage at full charge (according to CC) was 2.10v. the tech info i have download suggest that it should be max 2.16v. Has anyone other there has any experience or heard anything about these agm's. (apparently they have sat idle for a number of years after delivery from manufacturer and were never installed into the telecom site i got them from, the techs gave them a charge for the first time a few months ago). I have read some where that catalyst caps, and watering the cells may help. anyone got an ideas or comments. your assistance will be gratefully accepted.

sunny, breezy, beautiful barbados.

Dapdan

ps. the link to the article i found online is

http://www.battcon.com/PapersFinal2008/DeMarPaper2008PROOF_7.pdf


I have found some additional info online for the catalyst cap if anyone is interested in them as well

http://www.batteryresearch.com/catalyst_products.htm

GO POWER 1500 24V, 14 KYOCERA TM&GT130, XANTREX C60 & C40, 1280AH HAWKER IND WET CELLS, 900AH GNB ABSOLYTE IIP AGM. RUNNING ENTIRE HSE SINCE SEP 08
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Comments

  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Dapdan
    The Absolyte batteries are some of the best batteries you can get. I had a set that were 9 years old when I sold them 3 years ago and they are still working fine for the people I sold them to. The Absolytes are sealed and never need watering. Do not try to open them or you will ruin them. As I remember I had them in a 12v bank and I set my controller go into absorb at 14.2v. (temp compensated) That is 2.36v per cell. Resting voltage on a fully charged Absolyte llp battery is approximately 2.12v per cell. When you charge them, let the amps going into the bank drop to 1% of the capacity of the bank and at that point you can consider them fully charged. For example if you have a bank rated at 1500 amp hours and you start chargeing it, it will take all the amps your charger can deliver, but as the bank reaches full charge your controller will start tapering off the amps going into the bank, when it tapers down to 15 amps (1% in this example) then the batteries are fully charged.
    Hope this helps
    Larry
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Link to Exide / GNB / Absolyte info: http://industrialenergy.exide.com/sub_navig.asp?main_description_en=Absolyte&lng=en&cl=np_brands

    HTH,
    Jim / crewzer
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Thanks crewzer,

    that is the info i have and have been using to set voltage points, but the charged rest voltage was max 2.1v and min 2.06v. i have read the links that i posted about the IOVR process and using catalyst replacement caps from Philadelphia scientific.

    tell me what you think if you are fimilar with their work or have read the link that i sent.

    Damani
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Low rest voltage on GNB absolyte IIP cells

    The paper is very interesting... I always wondered if the AGM's were failing because of loss of water--because of failing catalysts.

    The major issue may be the equipment needed to measure the cell's ohmic value so you know how much water to put back in...

    If you can "recover" capacity in an AGM for only 1/10 the price of new--does not sound like a bad idea. But the company is dealing with large cells--not sure how much help (replacement caps, tools, ability to measure water loss in a multi-cell battery) one could get on the smaller cells/battery sets we usually see around here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hi BB,

    well for me if i could buy 12 of these catalyst caps and install onto my free gnb agms it would work out for me. i found a site that indicates the price was $35 for one cap within one of the links i posted. i read on another forum where i guy opened a vrla 12battery and inserted 20cc of distilled water and it revived the battery the was otherwise not starting his mower and some months onward it was still working ok. It is an area some one should investigate and put a new product out there like how the hydrocap work for wet cells.

    Damani


    This is another interesting paper from the developers of the same catalyst caps.

    http://www.battcon.com/PapersFinal2003/VanassePaperFINAL2003.pdf

    Here is another link to a Sealed VRLA Solar Monobloc
    http://www.amberjac-projects.co.uk/SECtechdata/CELLYTE20TSG.pdf

    http://www.secbattery.com/content/images/articles/6-12TSG-2006.pdf
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hey Larry,

    i am glad to see someone else have some real world experience with these type of cells. fyi i set float at 2.23vpc and bulk at 2.36vpc taking in to consideration temp compesation and after two cycles of charge and discharge resting voltage for one cell was 2.05v and the remainder was either 2.10 or 2.09vpc. i was just wondering whether anyone knew of any attempts by others to improve capacity of these vrla. as i have noted in my links i have found some info relating to this (IOVR method) attempt to improve capacity. Have you tried or know of anyone who tried to desulfate these batteries with say a Solar Converters Bd-2 Battery Desulfator and got any positive results?

    Damani
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Dapdan,

    The VRLA caps are a new one on me...:confused:

    A long period without recharging and/or voltage differences between cells suggests your batteries may require an "equalizing charge". The old IIP manual says 2.35 V per cell ref 77 F (25 C) for 12 hours.

    HTH,
    Jim / crewzer
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hey all,

    I though i would give an update on my progress.

    I have made some progress so far.

    I have been able to raise the rest voltage of all of the batteries with exception of the one cell that had a very low rest voltage in the beginning. Whereas all of the healthier cells were 2.09/2.10 now those cells are all at 2.13v (10#) and and one is still at 2.09v (this one was always on the low side as well and started at 2.07v.

    I have added a total of about 10oz of water to 11 cells and about 18oz to the very low cell. I also equalized them and they all gases profusely (it was not recommended but i was adding water anyway and therefore was not worried about losing water)

    Therefore to date the resting voltage of the entire bank is 25.41v (after a rest of 24hr) as opposed to the initial resting voltage of 25.20v so i have had a useful increase of voltage. I put them on load from about 6 pm yesterday and ran the entire house. I checked the voltage the following morning to be 25.04v after 12hrs under load and 2kw of energy used (as measured by my Killameter). I will allow them to cycle on my house for about 4wk and then do the same thing again (add water and equalize) to see if i get another increase in rest voltage. Apparentlly the rest voltage of these cells when new is 2.15-2.17vpc so not bad for 10yr batteries sitting idle until i got them September 08 for free.

    I plan to carry out a capacity test but i need to get a clamp on DC ammeter first so I can accurately measure current discharge. I already have the current discharge tables.

    Cheers...
    Damani
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hi Dapdan, you have not mentioned if the battery bank was mounted on its side, though not critical it gave my GNB AGM a small boost in output. the electrolyte will not wick all the way to the top of the cell if vertical.
    Also a temp sensor is a critical piece especially that you are in the tropics.. I don't see it mentioned.
    lastly test cell condition under load to identify any weak cells.

    keep us up to date.
    thanks
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    hey west,

    I do agree with you that added water would no wick all the way up vertically and i should be in better shape sine my cells are horizontal. I don't have a BTS. I have made my own temp compensations although i am not to concerned about that now since i am tending to overcharge now trying to increase the rest voltage. These cells were also design primarily for horizontal installation of up to 8 cell module stacks to have an increase of energy density as compared to their vertical cousins the wet cells.

    Cheers...
    Damani
  • System2
    System2 Posts: 6,290 admin
    Re: Low rest voltage on GNB absolyte IIP cells

    Hello all;

    I am new to this site and found it as I searched for posts on the IOVR process, of which I am the developer. I will not bore anyone with details of what entailed going from our initial attempts at recovery of the VRLA AGM cells, but we did start out in 1995 with trying to recover lost capacity by just adding water with the volume per cell being determined by the individual cell's ohmic value as compared to load testing results. This was a very good short term fix and the positive results usually did not exceed 24 months. We eventually learned from other scientists that were also researching this PCL (pre-mature capacity loss) with these cells, that the root cause of the failures was Negative plate under polarization which led to over charging of the positives, increased charge current and off gassing which caused an increase in specific gravity of the acid (dry out). We used reference electrodes to verify this shift in plate potentials, and then modified our procedure to in addition to the water addition, the installation of a catalyst in the head space of the cells. We named this process the IOVR process (individual ohmic value recovery) This made the recovery last many years, but we still would find a fairly wide range of recovery of capacity. We eventually learned that in order to drive the sulfates that had been formed through years of improper under polarization of the negatives, that we had to boost charge the cells at a fairly high rate (2.50 VPC) and of course watch the temperatures to avoid damage, but that by doing this we were able to gain more of the lost capacity and maintain it longer. This final version of the process is the IOVR+ process, as all we added to the IOVR process itself was the high rate charge. The results are substantial.

    As most of you understand that if you know the design specific gravity of the cell, then by measuring the open circuit voltage you arrive at the designed open circuit voltage. For example lets use an older Absolyte cell with a specific gravity of 1.300, then you add the international formula of 0.845 to that value and you arrive at the correct open circuit voltage (after 24 hours off charge with no load applied) of 2.145. If you have a number that is less than that then you have either a partially charged battery, a sulfated battery, or one that has had the sulfuric acid diluted to some extent.

    A danger in continuing to add water to these cells is that too dilute an acid can damage the itnernal duss works.

    These type cells do work better when they are laying on their sides, especially in a cycling type application such as solar, due to an issue with the wicking height of the sulfuric acid on recharge.

    Presently we only have catalysts that are for the cells that are single 2 volt cells with straps between each of the cells. There are not catalysts available yet for the 12 volt automotive type cells.

    It is good to see that all of you are understanding of the temperature compensation issues during charging. What we have found is that at standard temperature of 25C (77F) that 2.25 VPC works well for standard float type igherapplications, but that for cycling applications that in order to fully recharge that you need to be above 2.35 VPC, with occasional charge regimes still higher.

    Just as an FYI, there are catalsyt assembleis made that will fit just about any 2 volts VRLA cell, it is all dependent upon the vent opening diameter and design.

    Sorry to be so long winded, but your application is almost a perfect fit for good recovery.

    PeterD
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hi Peter, thanks for the great information... I have 2 sets of 3-90A25 GNB AGMs (12 V config) and have been observing them as they have been acting strangely, ie recovering and holding V readings after removing /reapplying the same load.

    I have had discussions with the 'local' GNB reps and have my MX60 set to charge @ 14.3 v (2.38v/c) bulk, and float @ 13.5v (2.25 v/c).
    Currently max amps are < 7A.

    I note in your posting you did not mention charging amperage nor is it indicated in your paper here:

    http://www.battcon.com/PapersFinal2008/DeMarPaper2008PROOF_7.pdf

    what are your recommendations for:
    charging amperage? max / min
    Length of time for charge?


    thoughts about desulphators in conjunction with your system?

    thanks Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    hey peter,

    I is great to here from on of the person envolved in the IOVR process. I have been having positive result from just adding water. I would like to purchase some of the catalyst caps but they are not readily available online, could you advise in this regard. The main problem for me is that I can not execute the high current recharge process since i am charging with my panels and I dont have a dc charger that can deliver high current charging. Can you advise or give any ideas how one can replicate this charging process with the all of the expensive equipment that ordinary RE guys may not have.

    Finally, I dont find your post long winded at all and greatly appreciate your input and look forward to more of it in the future.

    Cheers....
    Damani
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    products from Peters co. can be found here:

    http://www.batteryresearch.com/catalyst_products.htm


    happy reading
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    hey thanks west but, I have already been to that site I just can't find anywhere where you can buy it online and have it shipped even on that same site. That is basically my issue.

    Cheers...
    Damani
  • System2
    System2 Posts: 6,290 admin
    Re: Low rest voltage on GNB absolyte IIP cells

    If anyone wants the catalyst equipped vent assemblies they can be obtained from Battery Research and Testing. Just e-mail info@batteryresearch.com and ask for catalyst equiped vent assemblies for your particular make and model battery. The price of these are $24.00 USD each. There are standard ones for all US manufacturers which also fit some of the European models.

    The vent opening diameter and type of thread or hooking design is what determines the unit. For example the GNB, Enersys, Exide, C&D, some Hawkers use the same type of "bayonet" vent fitting, but some of the opening diameters are different. The East Penn and Lucent use a threaded vent design. We also fabricate custom ones, when we can obtain the blank vent assemblies.

    Since I "think" that all of you are users and not competitors for the specialized battery services that our company performs, if you send me the model, serial number, and date code/serial number (off of the front of the cell) I will provide guidance as to how much water to add, and a way to make sure that you are not putting too much water into each cell, which is not a good thing to do.

    It is important to be able to somehow get each cells voltage over 2.40 volts (preferably 2.45 - 2.50 volts) in order to drive off any sulfates on the negative plates, plus to full charge them. I will have to think on how you can do that with your systems. Since I am not a knowledgeable "Solar Person" I do not know if you could bypass one cell (disconnect the one cell) and let the system charge the rest of the cells at the hgher voltage, then at the end of the day connect that cell back into the system for use over night, then the next day or at some later date bypass one of the other cells and charge at the high rate.

    Something seems wrong with what I just said but at the moment I cannot see it. What is the highest voltage that you can get on your systems? Probably a dumb question, but I do not know your equipment.

    If you contact info@batteryresearch.com you probably ought to ask for them to forward that to me, and we can discuss your specific applications.

    Have a geat day.

    PeterD
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hey Peter,

    Thanks for the reply and your kind offer in respect of the amount of water to add to each cell. I have added water to my cell but did not have an ohmic meter so had to guess on the amount to add after some lenghty research. To date I have added approx two sets of 5oz to each cell. My cells are the Absolyte 100A19 rated at 900Ah @ 8hr. With my setup my panels can input a maximum of 75Amps but not for an extended period of time and it would vary as the insolation would vary. The maximum voltage I could get my cell up to is about 2.60vpc (I had equalised them at one stage in an effort to deal with the sulphation). The numbers off of the cells are as follows:

    cell casing - 549319 near opening and KBA 8466 near the base or closed end

    on top of cell around the terminals - KBA 04C100

    My cell have an interesting history. If you check my previous post you see a chronicle of my progress. Apparently my cells were dormant/never used for appro 10yrs(going by the weight/ship bill on the cell when I pick them up) they were still in the pallet and wrapped in thick clear plastic. Brand new never used except quite old (date on bill 98' and I got them Mar 09') sometime in Sep 08 the manager that deals with them knew he was giving them so he gave them a full charge. When eventually got them nearly 6 months later I also gave them a full charge and discovered that after 24hrs resting the voltage on each cell was 2.09/2.10 and then two at 2.01 and 2.04. This is where i started to research them and found your wonder work and posted my findings along with white papers on this site.
    Having added water twice, equalising them and cycling them under regular loading from my house over a few month I got improvement to 2.11/2.12 from the first addition of 5oz of water and got to 2.13/2.14 on the second addition of water and that is where I am at right now. I also realised that some of the vents were not seating tightly and i was getting leaks around the edge of the vent(used diluted washing liquid to discover this). So when I get those cap from you I will kill two birds with one stone. That is a summary of my experience with these wonder full batteries. I would like to do a load test since I have the discharge charts but need a clamp on DC meter so I can set the discharge Amps and then time it to the required end voltage. I have done this so I am not sure what capacity improvement I have realised for my efforts. I have only been able to confirm an improvement in rest voltage.

    I greatly appreciate your time, input and advise on your great IOVR method. There are a number of guys using these type of batteries here in Barbados and I know they would be interested in your caps. Normally the local telecom company dumps these batteries when I know they still have life in them. So at the very least we are do some good for the environment.

    Cheers...
    Damani
  • System2
    System2 Posts: 6,290 admin
    Re: Low rest voltage on GNB absolyte IIP cells

    Damani;

    You are correct with the age of the batteries as KAB means that they were manufactured in the Kankakee plant in February of 1998. Also by your being able to raise the voltage during boost charge to an average of 2.60 VPC (volts per cell) you have really helped them. The 5 ounces of water was quite low as we normally, depending upon the ohmic vlaues of the cells, would put a MINIMUM of 8 ounces in each cell, and most likely with the age of your cells would put in up to 18 ounces total. And in some cases have added even more to select cells.

    I cannot emphasize enough how important it is to give the cells the equalizing that you have. In order to restore the correct polarization potentials to the negative plates, each cell needs that voltage to be at or above 2.40 volts.

    From looking at your before and after numbers on rest, you have done a very good job at recovering these batteries. Congratulations.

    For anyone interested the way to calculate the specific gravity of a cell is to measure the open circuit voltage then subtract 0.845 and it is the specific gravity of that particular cell. Of course there are variables involved, but this is just for your information.

    These cells always will perform better if they are laying on their sides (horizontal) than if they are setting uppright (with the posts and vents pointing upward). At least in most cases that is, as when the cells are setting with the plates up and down, after a discharge the acid has a hard time wicking upward. If the models are the 45 or 55 amp plates, which are shorter, then the problem is not the same.

    Also, you do not want to put too much water in the cell/cells so after addign water use a thin rubber hose that you can insert in teh vent opening and point it downward ( like how you can put your finer in there to feel for any fluid) and use a food baster (or a syringe) and suck back out any excess water that is not absorbed into the glass mat within 15 to 30 minutes.

    I am really interested in your battery, as I have taken cells that had not been charged in two years and brought them back but a battery that sat for 10 years off charge and has been brought back is a story to tell. We will need to communicate off line, as I am curious to loads, lengths of loads, etc, etc.

    Pete
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Yes, again thank you Peter for the information and offer as to what to do on each GNB model.

    As to the recharge/equalization:
    I was advised by an SAFT rep to reconfigure my 12V 'wet NiCd' units into 2 @ 6 V in order to 1/2 the 40 A output of my TC40 + charger into 2 - 20A pathways in order to maintain constant amperage. This allows for a continuous 20A charge for these cells, according to the literature SAFTs'wet NiCd' recharge better with constant Amperage and can withstand over Voltage's in an equalization mode. In this case the voltage will climb to +- 17V by the end of a 10 hr charge cycle


    The GNB manual recommends a max Eq voltage of 13.8 to 14.1 V (2.3 - 2.35 v/c) for 24 or 12 hours respectively...
    Thus the problem is, for the GNB's, to keep the Voltage < = 14.1V.

    Would the effect of 'showing' a 10 V (or less) battery to the charger not give the same high voltage (+-17v) result? My thinking here is that as long as the charger does not 'see' the battery reaching > 12 v it will pump in constant amperage AND the max voltage.. Am I correct in this assumption?

    Cheers,
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hey Peter,

    Thank you for your affirmation of my efforts. I went against conventional wisdom when I equalised my cells as most members of this forum indicated that you don't equalise AGM but my research had indicated that an EQ once a year during regular service life was essential. It is interesting that you can confirm the manufactured date of my particular cells and that confirms the story of the cells history from the guy who got them for me. I can confirm that my cells are indeed horizontal. I knew that adding to much water was not a good thing so that is why I only added a total of 10oz to most of them and about 18oz to the one that had te very low cell (that was intially 2.01 and is now 2.04). When i first got them and wire all together for 24v my max resting voltage of all was 25.2 after my efforts today that voltage is 25.5 so I have achieved my initial goals.

    I know i can further improve their performance but i have no way of being more accurate in terms of volume of water to add since I have no way of measuring ohmic properties and I don't have a base line capacity to which i can compare result to so I have not done anything else until I can quantify those parameters for fear of inadvertently causing damage.

    I believe that these particular cells are perhaps one of the best made or the best made out there today base on my research and actual results from my experimenting and the particular history of these cells (dormant for 10yrs with perhaps no charging or very little charging for that period and still able to perform very well under cycling condition of my setup). So when I see anyone considering large agms or having teh oppurtunity to get use one I encourage them ( Like TnAndy).

    Cheers...
    Damani
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    As long as you are adding water, and equalizing, what about this untested thought:

    Add some EXTRA water, and let it bubble off in the EQ cycle ? (Just ounces, not pints)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    mike,

    you are right on the money of my thinking. That is why i really did not fear adding water and equalising because eventually one can off gas excess water. The challenge is that you don't really know when you are adding "extra water" since I can not tell when the cells are properly hydrated and you may acutally end up drying them out more. when I had equalised my cells using the C60 they gased violently. I observed this by allowing a dilute solution of washing liquid to soak into the porous section of the vent and as it was equalising it gave out alot of bubbles. In fact when it was charging normal it cells off gas as well but not as much when I was equalising them.

    Cheers...
    Damani
  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Another question for you Damani:

    The two "new" sets ( never installed ) had initial, just the way I got them, voltage readings a little over 2 volts/cell....the range was from 2.069 on the lowest to 2.078 on the highest.

    After 12 hours on the 40 amp Ioata charger, and letting them rest 24hrs, they seem to be holding in the 2.180 range per cell.....2.160 being the lowest, and 2.184 the highest.

    What condition would you consider these to be in ?

    How would I know IF I would need to try to add water ?

    Thanks,

    andy
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Tnandy,

    My goodness, I am totally envious. I wish my cells could read 2.16-2.18. Those I would say are in excellent condition, could you mail a set to me in Barbados:D. I would say don't add any water to the new ones but install the catalyst cap that Peter Demars company offer and that will insure that they are in tip top condition for the next 15-20years at least. Yes that is the kind of life you can get out of them. If your check the specification manual (available online) there is a graph of cycle vs dod (depth of discharge) and as an example if you cycle them to 20% you can get 5000 cycles (do the maths and see how many years that is if your cycle is a day!)

    Cheers...
    Damani
  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Well, heck, Damani.....send me a postage paid envelope, and I'll send you a set on down, buddy...... :D

    Yeah, I'd studied the life on these before I went to pick them up.....even at 50%, they have a 1200 cycle life....and keep on standby, the design life is 20 years......and hopefully, they WAY under rate that, and I have a 30 year set if I don't use 'em too heavy ( we are grid tied....these are backup, or "end of the world" use )

    I want to sell one set of them, as I think they are more than I need, but assuming I 'get stuck' with both, do you think 2400amp/hrs is ridiculous for the 18 175 watt panels I have ? I have the panels in strings of 2, running thru 2 Outback controlers, and they put out about 44-45amps to the controllers. I'm given to understand the charge rate should be about 5% of the amp/hr rate of the battery, so a 1200amp/hr battery should have 5% x 1200 or 60amps to it....so I'm already UNDER that with my system now, never mind having another 1200amp/hr set sitting there......BUT my thinking was I bought this 500 buck Ioata 40amp charger to do the initial charge on the battery sets.....and since I have it now anyway, what I would do is keep one set on the Ioata, and simply trickle charge one set from grid power....and let the other set get charged from solar. Wire them so I could use both sets IF the grid went down, or swap from the Ioata to the solar on either set for charging.

    We don't use batteries much......but IF we did need them in a temporary grid down situation, I'd be sitting on 2400a/h capacity versus 1200. I know if grid power went away long term, my solar wouldn't keep up both sets.....I'd have to increase solar, or use a backup generator to keep them going.

    I ask you because you have 1,820 watts of panels and a 900a/h battery and you DO use yours for you power I take it......

    Thanks....

    andy
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    tnandy,
    you could keep both battery banks and charge them as you propose, but that iota would make a big trickle charger and most likely you'll want to speed up the charge on the primary battery bank with both the pvs and the iota. 40a+45a=85a and dividing that by 1200ah is about a 7% rate of charge. so what you could do for the spare battery bank is to keep them trickled charged with a separate pv system that consists of a simple pwm controller and about 12a of pvs. why 12a? this is about a 1% charge rate and should do fine to maintain the batteries.
    the use of a few blue seas switches and some heavy cabling can alternate between the banks too
  • Dapdan
    Dapdan Solar Expert Posts: 330 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    Hey Tnandy,

    niel advice is sound as usual. I would confirm that my system is 24/7 and the numbers you state are correct. Further to that My consumption is approx. 5.5kwh daily or 200Ah at 24v. Quite often during the day around 2pm my system goes into float and this is while loads are still on the same batteries. I run a very tight ship down here and consume 180kwh - 200kwh. per month so my solar on average produces more than I consume by about 10%. You will have to do the math on your loads and your average daily charging total to get a better handle on your potential. Why dont you just run some select circuits 24/7 on your batteries (ya know critical loads like lights and some outlets) so you can reduce your reliance on the grid.

    Cheers....


    Do you think a #10 envelope would be adequate for shipping purposes.;)
  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells
    Dapdan wrote: »

    Do you think a #10 envelope would be adequate for shipping purposes.;)

    I had in mind one of those larger, manila type envelopes...... :D

    You DO run a tight ship there, energy wise. We get a good infeed tariff here that makes it financially attractive to keep feeding the grid, and the way my inverter works, it's all grid or no grid.....so it would require some re-working to do what you suggest and just run part of the house on my solar.

    neil's suggestion of separate panels to trickle charge the extra set might well work.....I'm always open to buying more solar stuff since the wife won't let me have a bass boat.....ahahahaaa
  • System2
    System2 Posts: 6,290 admin
    Re: Low rest voltage on GNB absolyte IIP cells

    TnAndy;

    Do you know what the date code is on you batteries? It is a code that is either stamped or etched in the cover. The first letter is always going to be a F or a K. The second and third letter are the month and the year of manufacturer.

    I am interested in their birth date.

    Pete
  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    Re: Low rest voltage on GNB absolyte IIP cells

    I'll check them and post it, Peter....