3100 amp hour bank....2k watts of panels .. outback 80...4k watt sine wave Aims inverter...

herbgh

I recently bought 5600 lbs(approximately)  of 2 volt cells. 36 of them(telecom stuff) .....I say pounds for I knew, at the time, that I could scrap them for 24 cents a pound....and I paid 37 cents a pound...  1800 dollars....they are sold by Panasonic and Energys...the Panasonics are 1040 amp hours at an 8 hour rate.. weigh about 146 lbs each and are 2 volt cells, agm,sealed lead acid.  the ENergys are same but 1020 amp hours each... and weigh about the same..

  My questions...what voltage should I see at 50% discharge...and what is fully charged voltage?  I have been under clouds with little or near no solar input for nearly three days...and the cells read 2.05 to 2.06..   After a good solar day...I go into float in the early afternoon...and see 2.15 or above...on each.. bulk charge is 28.4, adsorb is similar, and float is 28...  Running a fridge,tv, computer and lights currently..spring house pump will go on soon..as will clothes washer and microwave... have tankless water heater and heat with propane..

   Not sure of the age of the cells and replaced 4 370 amp hour 6 volt batteries with these...Inverter is 24 volt input..cells are in 3 banks of 12 of course... I was looking to buy 4 more 6 volt 370 amp hour batteries for $1200 ...Trojans(no core charge)..when I found these...for 600 bucks more..

  What would be the available kwh of these batteries assuming good condition and fully charged...?

  I would like to rigg up a timed discharge test to see the condition of these cells...any suggestions.. then again...using them with a kil o watt meter on the output of the inverter should be a test also...just remove the charge controller/panels...and watch the cell voltage over days and compare it with kwh?   Thanks...I ramble...hope the jist is there...:-)   Herb

jcheil

Telcom batteries generally don't work well for Solar installations. They are designed for "float service" and can usually only be cycled a few times before they die and need to be replaced. That is why the telcom companies get rid of them every year or two or immediately after a long power outage.

Also, the "8 hour rating" on the batteries is not very standard. Everything generally uses the 20-hour rating. So it will be hard to tell "what" amp-hour rating they would really be at 20 hours. But just guessing, I would say that you have WAY more battery than you could possibly charge with your current amount of solar (just guessing you had enough to even properly charge the 370ah bank you had before).

I run a 1100ah battery bank (Trojan L16RE-B's) and need about 10k of solar to properly charge it down here in sunny Florida. I do have a lot of base loads, but remember you want to try to maintain a 10-15% charge rate. Which in the case of a 1100ah bank is between 110 and 165amps of solar current (then add additional current for your base loads). 

Not trying to rain on the parade, but I think you will be very unhappy with those batteries and they will be dead real soon.
If you have a specific model number on them maybe we could find out some more information on them and give you a better idea on the charge rate needed for them. And with AGM batteries, you must specifically follow the manufacturers charging instructions precisely or you will boil them dry. Additionally, since they are sealed batteries you can't check the SG which is the ONLY real way to check the condition and state of charge of any battery.

Imurphy

Assuming you are talking about Enersys PowerSafe Calcium cells. They are designed for float service. Float Voltage of 2.17-2.26vpc If they are suffix "b" they are 1.250NSG and wasnt 2.21-2.30vpc. They spec a freshening charge voltage of 2.5vpc. If you are only charging from solar I would say IMHO a setting of 2.33-2.40vpc would be appropriate. according to the MFG this is generally an equalizing charge voltage, but being you are not using them for float service and will be cycling them, and charging with solar. a higher voltage setpoint is needed. Just set the HVSD at 2.52. The biggest issue you may see with these higher voltage set points is electrolyte flooding onto the cover. keep the electrolyte level right at the low mark. The manual states to not refresh charge, or equalize these cells unless the electrolyte is at the low mark.

Also the Calcium plate cells are rated for 50 cycles at 80% discharge. But that is just to min name plate rating. They will live a good bit longer than that.

WaterWheel

Man,    you guys are giving herbgh some really rough news.         I'd have bought the batteries myself not realizing their limited cycling life.

techntrek

I'll jump in on the bad news bandwagon.  Aims isn't all that great, and 2 kw at 24 volts is pushing it.

jcheil

techntrek said:

I'll jump in on the bad news bandwagon.  Aims isn't all that great, and 2 kw at 24 volts is pushing it.

I can tell you some HORROR stories about Aims also. I went thru 2 of them in a 2 week period before I finally gave up on them. 

H2SO4_guy

Hi,

I have 56 of probably the exact same Panasonic cell.  I am now at 29 months running them and they are very good.  I don't discharge them below 60% very often, but they will sure will put out some serious amphours.  If you want the charge specs that I use I would be glad to give them to you.  I think they are awesome.  I run 2 strings of 24 in series for 2080 AH @ the 8 hour rate. 

I often heat with electricity at night and run a heat pump for AC in the summer off of these. 

Good luck and let us know. 

herbgh

To clarify a bit...the Panasonic's are MSE-1040's  and the Enersys are DDM-85-25..1020 amp hours and the Panasonics are 1040 amp hours spec ed at the 8 hour rate.. 
  I should say that I am not using them in a high discharge mode...and do manage to get them into float on a good day ..
   I gave 37 cents a pound for them at a time when I could resell them for 24 cents a pound...so the gamble at that time was 13 cents a pound...about 600 bucks...with the China economy as it is...not so sure now...?

  The aims 4k watt inverter works fine..but I have called three times and never get an answer...so I am a bit down on their technical support... What are the failure modes that have been experienced?  

   Thanks  ..Herb

    

Vic

herbgh,

In the search box on this Forum,  place the term,  "aims inverter"    (including the quote marks),  and see what comes up.

FWIW,    Vic

softdown

We have guys that have forgotten more than I know.....but I will chime in nonetheless. Size matters in batteries. As much, or more, than anything else. You have an immense battery bank at a very reasonable price. You paid about 1/3 of new prices for lead acid forklift batteries. AGM costs a lot more and has plenty of pros and cons. I'd say....well done.

Only recommendation: either decrease energy usage or increase panels. You want to hit "Float" mode almost every day.....not just on good days. I'm thinking that you want to hit "Float" mode at least 90% of the time. Though I am not an expert on that.

Hopefully BB may chime in and set the record straight. We have a lot of experts here but most of us have our biases/prejudices.

BB.

At this point, with solar panels being cheap and (in general) batteries being expensive, having more solar panels is usually a good investment in keeping your battery bank happy.

From what I have read (I am on grid, not off grid), you have several options for running your deep cycle battery bank (does not apply to non-deep cycle type batteries).

1. Get to float several times a week (basically aim for >90% state of charge--Do not try for 100% state of charge every day--That is close to equalization charge every day, which is very hard on a battery bank).
2. Go ahead and cycle the battery bank daily between 50% and 80% state of charge (lead acid batteries are very efficient when charging in this range)--And recharge to >90% once per week. An alternative to what people normally do, but is probably a pretty good way to keep the battery bank happy). Note, if the battery bank is going to set for days/weeks, make sure the battery bank is charged >90% before leaving... The 50% to 80% only is good for daily cycling as sulfation will occur if the battery bank is not actively cycled when below ~75% state of charge.
3. One vendor (Rolls/Surette as I recall) said that you can do the 50% to 80% daily cycling and recharge to 100%(?) once per month (monthly equalization anyway?).

-Bill

herbgh

Currently I charge these monsters(to me anyway) ...by using my Schneider/Xantrex inverter/charger... tapping 6 of the cells...and doing a three stage charge with the 100 amp charger side of the 12 volt  inverter.. A TR2412 model..that I retired when I got the Aims...4k 24 volt unit.
  My monthly usage from the power co is in the 100 to 150 kwh range..and quite a bit of that is spent doing the above exercise..plus a clothes dryer,
 Been unusually cloudy in South cent Ky.. My bill is in the 25 to 32 dollar range at 10 cents or a bit less for each kwh...18 dollars of that is some  sort of arbitrary fixed charge that has no logic...! :-)   well! just because they can!!

    I think I need to sell two sets of the Enersys cells and rely on the 1040 amp hour set...Panasonics....that way, my 2 kw of panels might just do the job with a bit of help from the 50 amp 24 volt charger that is part of the Aims unit... Currently I plug it in when I see 24.9 volts on the banks...

  I have propane for heat and for  tank less water heating.. and there is just myself living on my 35 acres...small 1000 sq foot home...

   all advice is welcome...all help is appreciated...way down on the learning curve...Herb

Vic

A Quote from BB Bill;

"3. One vendor (Rolls/Surette as I recall) said that you can do the 50% to 80% daily cycling and recharge to 100%(?) once per month (monthly equalization anyway?)".

Yes,  believe that this is Surrette Bulletin #614.  In a conversation with Surrette Engineering,  it was stated that this Bulletin was written to accommodate "concerns"  that some customers had with Charge Acceptance with Surrette battery banks in off-grid use,  that seldom,  if ever,   experienced deep discharges.

This Bulletin has undergone at least three revisions,  the following appears to be the latest rev:

https://www.altestore.com/mmsolar/Others/Charging_and_Discharging_BU-RS-614.pdf

FWIW,   Vic

softdown

Seems to me that one could worry themselves to pieces about proper battery maintenance. Pretty sure that I have read at least 100 different recommendation on battery maintenance.

If one has a strong solar array, is energy conscious, and lives in a very sunny environment.....the batteries will achieve a 100% charge at least 95% of the time. Mine have failed the 100% charge about four times in the past ~9 months. I do not see how achieving a 100% charge could be anything but beneficial.

Interesting that Rolls recommended a deep discharge prior to the Equalization charge. Having read, on this forum, that batteries should be 100% charged prior to Equalization....where does that leave the solar user?

The fact that manufacturers keep changing their recommendations could allow one to conclude that this is not established scientific fact at this point in time.

herbgh

I am having trouble understanding "equilization" and AGM cells??  I do not attempt it  for I cannot see any stratification given the construction...

   By the way..Outback Energy (Outback 80  folks) sell the Energys 2 volt cells in banks of 12,24 or 48 volts..for a pretty penny.. Herb

BB.

As I understand, AGM cells can still get "out of balance" (state of charge is not the same across all cells). It just takes much longer with AGM vs flooded cells.

A few years ago, a thread here talked about one AGM vendor that recommend equalizing (every 6-12 months) by extended charging time at the nominal charging voltage (typically 14.4 volts or so)--I do not remember the details (possibly called a "conditioning charge" and held for ~8 hours???).

-Bill

westbranch

Herb, here is a 'little' primer for you on how lead batteries in general  and AGM function from the maker of my AGMs.  There is a lot in this manual, I've read it several times over...

http://www.cdtechno.com/pdf/ref/41_2128_0212.pdf

herbgh

I read it ,,dozed off several times...but saved a copy...thanks....still learning...Herb