Commissioning a new battery bank

stillchillin · February 2012

Hi, I am having some problems getting the SG above 1175 on my battery bank. Here is what I know so far. The batteries are surrette 4-KS-25PS 4V 1350 Ah., I have 12 of them in series
In the beginning I was charging them with a 6.5 KW generator because we were building our house, we are off grid. I was careful and never let the voltage get below 47.4V. The loads were minimal, some power tools, lights, radio, etc. This went on for about 2 months until I was able to connect the panels. The panels have done fairly well keeping the voltage around 48+ V. I had to add about a half gallon of water to each cell in the beginning. A week ago ( now we have been using the batteries for about 4 months) I performed my first EQ, starting SG was 1120, temp 64F, voltage 51.5, 4.31 per battery, after 4 hrs SG was 1175 after 2 hrs rest voltage was 52V temperature @ 65 degrees. I am EQing again today as SG readings are still @ 11.50-11.75. I know how important it is to keep the SG at the proper level. Am I getting a lower reading because I added so much water about a month ago ? And it has not had a chance to mix yet ? There was a lot of head space above the protection plate which is above the actual battery plates. That is where the water was when I received the batteries, apparently they ship with minimal fluid. I would appreciate any input. Thanks Steve

westbranch · February 2012

Re: Commissioning a new battery bank

Well you should have an SG of 1280 according to their manual http://www.rollsbattery.com/pdf/4KS25P.pdf
and be at ~ 57.6V for charging http://www.rollsbattery.com/files/userfiles/SolarBatteryManual.pdf

HTH

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

Wow, what a Monster Battery Bank and Expensive. It's sounds like it's been woefully under charged and sulfated. It's going to take some TLC to get it back up to where they should be. I guess you have a good 3 stage Charger that can also Equalize , sized for the bank ? i don't know if you can do it this time of year with your Solar., maybe but you'd have to play with and see.

You should be taking it to

Bulk 57.6 V
Absorb @ 57.6 for at least 2-3 hours After you know the SG's you can tailor the time.
Float 53.6 V

Equalize @ 60. 8 V You are going to have to watch your Temperature and don't go much over 120 F ( 50c) I'd try it for a hour then check the SG. It could take you 4-5 times or more to get them cleaned up.

mike95490 · February 2012

Re: Commissioning a new battery bank

Give your appliances a couple of sunny days off, or fire up that genset in the AM, and bulk the batteries for a couple hours, and let the sun do the rest.

Do you have a way to program your charge controller for the proper settings ?

After a day or two, of good bubbling while charging, the water and acid should be pretty well mixed. When reading SG, are you factoring in the temperature correction ?

icarus · February 2012

Re: Commissioning a new battery bank

I would argue that your stated loads are not "minimal" Power tools, lights, radio etc, cumulatively add up to a significant number of AH, even on a big battery bank. My guess is that you have seriously damaged your batteries, shortening their life at a minimum, killing them in worst case.

If they have been sitting at ~ 1120 for any extended time, my guess is that they are seriously sulphated. Consider reading the following:

http://www.batteryfaq.org/

http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

By the way, 1.170 is considered 25% charged,, a sure recipe for killing them:

http://www.reuk.co.uk/Battery-Specific-Gravity.htm

Also, related, if you have been "careful not to let them get below 47.4" (un loaded!) is essentially,, dead.

Additionally, your float voltage (unloaded, after being off charge at least 2 hours should be closer to 58 volts, 52 just coming off charge is,, essentially still,,dead!.

I don't know what you are using to charge them with, but they want ~ 175 amps of current,, and at 48 vdc you would need a genny at least ~8.5 kw to do the job. Once again, too much battery, too little charge current. How much PV are you going to install to charge such a big bank? My quick guess is something in the 10 kw range is going to be what is needed. Your current PV would only produce about 1/2 of what you are going to need.

As a side note, the biggest mistake people make with off grid systems is oversizing the battery bank, relative to the charge capacity. It all goes back to the basic equation: Start with the loads, find the battery bank that fits that load, and design a charge regimen to fit. Your battery has a capacity of ~64 kwh, draw to 50% SoC and that leave 32 kwh. Divide that by 3 for 3 days of no sun, and that would leave an average daily load of ~11 KW. Do you really expect to draw that much on a daily basis?

Your 4.2 kw of PV might provide, by my quick rule of thumb 4200/2=2100*4=8800 WH day, on average over the course of the year. Once again,, I thinkt he battery bank is too big.

You might be able to preserve some life in them with some proper charge regimen, and perhaps some excess eq to try to drive the sulphation off the plates.

Good luck, and keep in touch.

Tony

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

I'd think that with the FM 80 and the 60 amps from the Magnum you can do it , but your in a deep hole and once you get them up, then you'll have to watch and use them in conjunction with each other to give you enough Amps when needed. Like Icarus said, you have way to much Battery to put them on Cruise Control. Spring and Summer, you'll have a easier time keeping them properly charged depending on your loads.

BB. · February 2012

Re: Commissioning a new battery bank

For expensive (and sealed/AGM type) battery banks, a Battery Monitor (Victron is another brand that has been praised here before) can help you keep better track of your battery bank's state of charge by logging the current*time in/out of the battery bank and displaying 0-100% state of charge (great for spouse, kids, guests too). Much easier than taking specific gravity readings every day--and much more accurate than monitoring bank voltage (although, battery monitors do have their own quirks too).

By the way, were the plates still covered by electrolyte when you filled the cells the first time, or were they exposed to air (not a good thing)?

-Bill

Vic · February 2012

Re: Commissioning a new battery bank

Most of the important things have already been said.

IMHO, you have not been paying nearly enough attention the NEEDS of your battery bank.

YES, you must fully charge the bank in the next several days. Pretend that it is important, and that you have spent about $16,000 for that bank. This might help this task rise to the proper level of importance.

Any SG below 1200 is very bad, and must be corrected immediaely.

IIRC, each cell of those batteries holds almost exactly 5 gallons of electrolyte. Being down 1/2 gallon per cell is not good. The recommended fill level for those batts is between 1/2 and 1/4 " below the bottom of the Vent Tube.

You have NOT EQed the bank yet, given the voltage & SG readings you mentioned at the end of EQ. EQ does not really start to take place until the bank has spent hours at the correct Asorb voltage, and then rises above that value by several volts in a 48 V system.

AND, would you please tell us what your Asorb voltage, and time is? Or if you use Return Amps to terminate the charge, what is that setting?

The Never below 47.7 V statement may not be too bad, if there are significant loads on the batts when that reading was taken.

I believe that these Surrettes are shipped with 1.265 SG electrolyte. Surrete changed their data sheet several years ago, as they were specing capacities as if the electrolyte WAS 1.280, but were shipping batts with 1.265. They changed the data, but not the strength of the electrolyte.

Agree that you probably really need a larger genset, and more charger for Winters. Perhaps you are in a perpetually sunny part of VT, otherwise it could take days and days to recharge your bank from Solar plus Inverter/charger.

Large banks need similarly charge sources, that can be counted on when the weather turns bad.

If your loads are really smallish compared to the bank capacity, then the rule of 5-10% of 20 hr capacity often does not apply, BUT, then, you really need to be able to charge that bank at a 100-150 Amp rate. Many believe that for the health of the bank, occasional high-charge rates are required, and good for the batteries.

Make certain that your means of measuring SG is accurate. Make certain that each of your charge sources have BTS/RTSes. Check the settings on your chargers. If this bank were mine, I'd move Heaven and Earth to get it recharged, and then EQed within the next day or two. It is possible that it could take tens of hours of genset run-time to do it, even with some sun. As you know, the total capacity of that bank at the 20 hour rate is about 95 Kwh. And neither chargers nor batteries are 100% efficient.

Furthermore, as you probably know, SGs need to be temperature compensated. If the batts are cold, and you or your Hydrometer (or whatever you measure SG with) have not compensated the SG readings, then the SG could be even lower than you mentioned .. some guessing.

EDIT: Boy 24 cells X0.5 Gal + 12 GALLONS down on electrolyte!! !!!
Was a dealer invlolved, or, did these batts drop ship from Surrette? Was there an indication that much of that electrolyte was spilled. -- was any packaging film totally saturated and dripping acid? Were the pallets completely brown/black in color, and dripping electrolyte? Any evidence that the pallets were tipped on their sides in shipment? Was each cell's electrolyte level consistant with the others?

One of my 4KS25 banks had evidence of very rough handling in shipping -- acid everywhere, and the top of one Jar (cell) had a broken weld where it is joined to the top piece. Discovered this when, after hand-trucking it to a power room, the electrolyte level had dropped several inches. End EDIT >>

We all with you very good luck. Please do let us know how you are doing. Many of us honestly do care about you and your predicament. Vic

stillchillin · February 2012

Re: Commissioning a new battery bank

Thank you all for your input. I will try to answer a few questions now, today is busy superbowl and all, This morning I have readings of 1200 and better I do have a good instrument. According to the CC I am producing over 3 KW / HR this AM. According to the dealer I bought the equipment from the Magnum will only allow a charge rate of 3kw with the generator I dont know if that is adjustable. At the end of a 4 hr EQ I was charging at 61.2 V @65A. does that sound right? The health of my batteries is my main concern and I will be diligent in correcting this condition. I appreciate the feedback and know it is all meant to be helpful. I will keep you all posted. We did plan on 10KW per day at the start of planning and may add a 2KW wind generator down the road.The water level was never low enough to expose the plates. Thanks again everyone

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

The Magnum MS4448PAE has a adjustable output, but you have to have the ME-RC50 remote display to do it, I would think you have that, but maybe not. The Issue may be the output receptacle on the generator. Most portable generators only have a 30 amp ( 6500 has 2 , 30 amp, if your using both ) , not knowing, means you are limited 50 % of the output. Thats a issue you need to check out. From what you posted, the batteries want to come up, you just have to keep at it,

stillchillin · February 2012

Re: Commissioning a new battery bank

I have the remote, the generator has a 50A 250V twist lock outlet thats what I'm using. Thanks SP, when you say output do you mean whats left over after the charge current? Thank you

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

stillchillin wrote: »

I have the remote, the generator has a 50A 250V twist lock outlet thats what I'm using. Thanks SP, when you say output do you mean whats left over after the charge current? Thank you

Great, 50 amps is plenty. remember you are sharing that with your house loads. You should be able to run the charge rate up to 100%-60 amp output on the charger.

The Spect sheet said 30 Amp 6500 maybe not on your model.

I have a similar setup, I use separate chargers with my generator so I can charge and still invert. I don't think you can do that with your Magnum , I believe it transfers to your input power source. I can be wrong. I have a 20KW generator and 4-12 V @ 60 amp chargers setup to do distributive charging.

stillchillin · February 2012

Re: Commissioning a new battery bank

I am a bit perplexed by my data, my outback is in float already this morning started in bulk for about 1/2 hr then absorb now its floating. shouldn't this mean I'm closing in on full charge. SG around 1200+/-. Remember I did a 4 hr EQ last night. Back to charging with the magnum, 3 KW for charging the balance is inverted as required ? Thanks

stillchillin · February 2012

Re: Commissioning a new battery bank

It is only my wife and me living here. We are aware of our limitations being off grid. Laundry during sunny days that sort of thing, its a new house all energy star, foam insulation, Grundfoss softstart pump. I think we can live off from 5KW/day if need be but dont mind running the genset for the health of the batteries. The learning curve is still a bit steep but manageable. This is some thing we have wanted to do for years. I have a first edition "OTHER HOMES AND GARBAGE" maybe they only had one print I dont know but I bought mine in the 70's. The power company wanted 80K to run power up our driveway!, so solar was a no brainer.Sorry didn't mean to ramble, anyway I've been reading the threads trying to fill in the blanks, have learned a lot thanks to all who don't mind sharing their experience will those who are in need of info and support Thanks

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

stillchillin wrote: »

I am a bit perplexed by my data, my outback is in float already this morning started in bulk for about 1/2 hr then absorb now its floating. shouldn't this mean I'm closing in on full charge. SG around 1200+/-. Remember I did a 4 hr EQ last night. Back to charging with the magnum, 3 KW for charging the balance is inverted as required ? Thanks

You need to get the SG's up, The CC is only shutting down with Charge Voltage as the trigger or Time. Two ways to do it, either higher bulk Voltage ( post what your using ) or extending the adsorb time , 2-3 Hrs. That you can set on the controller. It's going to take some trial and error to find that setting. I'd keep on EQ ing till you get them up, you can do it over a couple days . The 60V is fine, just watch the temperature of the batteries. Once you get the SG's up then you can adjust the CC you need get a fixed point with the SG's

If you have 50 amps coming in and the charger is using 30 amps it is power sharing with the Inverter.

Vic · February 2012

Re: Commissioning a new battery bank

Hi still,

Several questions:

1. On the FM CC, What is the Asorb Voltage? Asorb time?
2. Are you using Remote Temp Sensors on CC and Inverter/Charger?
3. What approx temp is the electrolyte on batts?
4. Did you measure the SG when you received your batteries -- best to record the SG of each cell at arrival (?).
5. Did you carefully note the electrolyte level of each cell of the bank at arrival?

With low SGs, you could set the Asorb voltage to 60 volts.
For Surrettes, an EQ voltage is a MINIMUM of 61.9 volts, and this should be temp compensated, either by you of the charger. Some chargers do NOT temp comp the EQ voltage.

In re-reading your initial post here, IF the batts came to you with very low electrolyte fill level, then it is possible that the only reason for the low SGs is that electrolyte needed to be added.

DID A DEALER SUPPLY THESE BATTERIES? OR, WERE THEY DIRECTLY SHIPPED TO YOU FROM SURRETTE?

Thanks for your patience with folks like me, beating up on you. Vic

stillchillin · February 2012

Re: Commissioning a new battery bank

57.6V for 1 hr there is a place to set absorb end Amps ,on the outback, its 0A
yes there is a temp sensor with both the CC and the Inverter
battery temp 64 F
No
the electrolyte level was the same on all batteries just over the horizontal plate I needed to add 1/2 gallon to each cell (1 gallon per battery)
The batteries were drop shipped from Rolls I think MO.
Its OK to beat up on me I appreciate the attention. Thanks Vic. Stillchillin

stillchillin · February 2012

Re: Commissioning a new battery bank

This is a direct quote I dug up on an email to me "All batteries are shipped with lower than optimal liquid levels. The liquid acid should be supplimented with distilled water only."

BB. · February 2012

Re: Commissioning a new battery bank

Just a minor beating up :roll:.

When you type about power and energy... Watts is a rate (like miles per hour, gallons per hour). And Watt*Hours is the amount of energy used (like miles driven and gallons pumped).

It is a very common mistake (I used to make it all the time when I first posted here) as we are very used to saying things like MPH and MPG.

So, you use 5kWatt*Hours (5 kWH) per day, and you have a 6.5 kW genset. Which if it ran at 4kW for 2 hours would output:

4kW * 2 hours = 8 kWH

Not a problem with your posts to date--Your context make the kW and kW/H (kW/H not normally used as it means change in current over time--like acceleration vs velocity) typos obvious what you really intended (kWH and kW).

When you take the time (and generator fuel) to bring your battery bank back to 100% S.G. readings... Once every 30-60 minutes, take a SG reading. When they stop going up between readings (measuring all cells while equalizing), then that is where you can stop.

When charging, look for cells that bubble more (or almost none), and measure voltage at each cell/battery group and look for differences. It is possible to have a bad cell (shorted/open/other issues) that needs to be replaced as it is causing problems for other cells in series or parallel (open cells stop charging current in series connections, shorted cells bring down paralleled connected strings).

And as Vic asked--Was there any obvious spillage of acid when you received the batteries? It is good that the plates were never exposed. But adding 1/2 gallon of water to a 5 gallon cell that "lost" a 1/2 gallon will bring down the maximum SG by ~0.026 points. It is also possible that the battery was not filled 100% to lessen the chances of spillage during shipping.

-Bill

Vic · February 2012

Re: Commissioning a new battery bank

Hi Still,

Thanks for the info. Because you are having some trouble getting SGs up where they need to be, IMHO, the Asorb V needs to be higher. Try 60 V on the FM, AND, the Asorb time is too short. Try 3 hours on the FM.

What does "MO" mean in this .., "drop shipped from Rolls I think MO" ?

If these batts came with very low electrolyte level, it is quite possible that they were short-filled at Surrette. In this case, IMHO, the low level needed to be made up by the addition of ELECTROLYTE. And if this was the case, then, the low SGs might be due to too much water in the mix.

IIRC, the spec on the "Reserve Capacity" (think that this what Surrette calls it) is 3.75 inches above the plates, or the "Moss Guard".

I would recommend that you immediately contact Surrette Tech SUpport via phone or e-mail for advice on how you should determine the correct course of action. I have had very good support from Surrette. And, afterall, you are a good customer. Recall that Serge is the Support manager there.

Good Luck, Vic

stillchillin · February 2012

Re: Commissioning a new battery bank

shipped from Missourri maybe michigan I dont remember anyway I will bump up the Voltage and time for absorb charge as you recommended, Thanks, Stillchillin

stillchillin · February 2012

Re: Commissioning a new battery bank

there was issues with the battery shipment, one battery had been punctured by a forklift but was replaced by the dealer/shipper I'm not sure but it was no charge. I checked the fluid level in every cell and they were all the same, just above the moss plate. Would you recommend adding electrolyte during the next watering if the SG doesn't come up. I was told to add only distilled water from the get go. Thanks, Stillchillin ps; Iget the kwh watts volts forgot who I was talking to spent 30yrs in the trades. thanks for keeping me honest

westbranch · February 2012

Re: Commissioning a new battery bank

Maybe that explains the 1.280 SG in the model specific specifications http://www.rollsbattery.com/pdf/4KS25P.pdf ...??

watering down drops 1.280 to 1.265?? page 6 of http://www.rollsbattery.com/files/userfiles/SolarBatteryManual.pdf

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

I wouldn't add anything with a 10 year warranty unless directed by Surrette and I'd document that, $16,000 is a lot of money to be playing with.

There was a post here a few years ago where a Surrette tech had someone change the SG by removing some of the electrolyte and adding some fresh known mix. Another post Someone made that was a battery specialist in the Air Force said they did it all the time with Aircraft batteries. Personally I have never did it with a Battery that had been used. On a new fresh battery, I'v added it plenty of times.

There is a certain procedure that I read somewhere about how you put a dry battery into service. It wasn't just dump it in and go. It was a time and temperature thing where you measured the voltage and the increase in voltage and charging if necessary.

Try this, not the one I read, but it'll work.

www.enersys-emea.com/.../DCS705B_1209.pdf

Vic · February 2012

Re: Commissioning a new battery bank

Completely agree with Blackcherry. Add nothing but distilled water, unless directed by Surrette FACTORY tech.

Recall that there was a large distributor of Suttette in the SE .. perhaps in MO. So looks like a dealer/distributor was involved.

Three banks of 4KS25s that I've dealt with when new all came with the nominal electrolyte levels at the factory speced level. Short filling may well be an attempt to minimize spilling of electrolyte.

All of these shipments had some evidence of spillage of electrolyte on the packaging film and pallets. Had wondered if some of the staining on pallets was during manufacture .. or at least filling at time of shipment. Dunno.

Recall that others have mentioned here that Surrette prescribed removal of some certain amount of electrolyte, and adding some certain amount of known strength acid to change the SG level in some cells ... recollection is dim.

Once again, DO NOT ADD ANYTHING, OR REMOVE ANYTHING (except Distilled Water) at this time. Please contact Surrette today via e-mail, or Monday via phone for instructions on what to do.

Thanks for the added detail Still..

And regarding any change to SG by adding H2O if the batts were short filled by mistake .. of course it is not possible for folks like me to know the packing density of the plates/separators in the plated parted of the batt vs, the reserve part above the plates, and this would make it difficult to extrapolate just the effect of adding so much H2O in the reserve volume, IMHO.

BUT, it looks like Surrette/their Distributor is intentionally short filling with stronger electrolyte, prob to minimize chances of spilling, and instructing the end-user to top up with Distilled water.

Still, when you EQ the bank the next time, you should determine if your charge source for the EQ temp compensates the EQ, and set the EQ voltage appropriately. It is recommended that currents during the EQ part of the cycle -- at the point where the target voltage is met -- be limited to 5 Amps per 100AH of 20 hour capacity. On your bank, this is still a lot of current -- about 60A. I might set the target voltage to about 62.5 V, before any compensation.

As BB noted (i believe), watch the electrolyte temps (almost never a prob with my banks), and monitor the SG change in at least the Pilot cell every 30 minutes minimum. You are looking for getting into the target SG range. Ideally, you should measure and record the SG of each of your numbered cells -- mark each cell of each batt with felt-tipped pen. Record these values in your notebook.

BB Bill also had a great tip. Under any reasonable charge current, measuring the battery voltage of each batt is a very good indication of the SOC of the battery (really the average of the two cells in each battery). As long as the charge voltage is constant, this is a great measure of RELATIVE SOC.

The Pilot cell is chosen by you, and commonly is the one with the consistantly lowest SG.

Lotsa data/opinion flying your way. These are great batteries in my experience. FLAs are very tolerant. Just try to get them fully charged and EQed TODAY if possible. Please contact Surrette Monday or e-mail today and follow up on Mon.. They are very responsive, and obviously know much more tham I about their batts. Vic

Good Luck, please let us know how you are doing. Vic

Blackcherry04 · February 2012

Re: Commissioning a new battery bank

A quick guess would be, as long as the SG's are coming up from Charging the ratio of the mix is fine in the electrolyte. The best analogy I can come up with this Battery Bank is like two neighbors, one feeding a goat and the other feeding a elephant in their back yards. On one hand you have a huge capacity and on the other you have to replace it. I am a Helicopter Pilot, you can get into a situation called " Settling with Power " you think your flying forward, but in fact you are going backward and down. The same can happen with batteries, you think your charging enough, but the capacity is going down. The SG is the known constant you can return to.

Vic · February 2012

Re: Commissioning a new battery bank

Well the added info that in the docs with the battery shipment, was that statement about the batts being shipped with LOW electrlyte level, and to top up with Distilled Water. Pretty much says it all. But Iwent to bed last night thinking that perhaps inadequate amount of 1.265 electrolyte was shipped in the batts, and the added H2O was a primary reason for low SGs, but, still 0.5 gals in 5 would not have made that much difference. But still there is the unknown of the ratio of the volumes of electrolyte above, vs below the plates and so on ...

At first, many of us had given still a bad time about ALLOWING his batts to get SO LOW on electrolyte, which in hindsight was a bit too rough on still.

I do like my elepahnts, as their temperments are slowly changing. But once one gets behind in feeding them, one needs a large shovel to catch up.

Go niners, Vic

niel · February 2012

Re: Commissioning a new battery bank

"I do like my elepahnts, as their temperments are slowly changing. But once one gets behind in feeding them, one needs a large shovel to catch up."

and here i thought all along that it was the more you feed them the more you have to shovel.:p

Vic · February 2012

Re: Commissioning a new battery bank

he he, Good niel.

Well that IS one area where batteries have a distinct advantage over animals. VB

stillchillin · February 2012

Re: Commissioning a new battery bank

Thank you all ,vic,SP,BB for your advice. I believe I am getting a grip on my problem, SG going up slowly. I will give you data you can analyze later. I have been keeping a battery journal for a while and have noticed some interesting changes as the SP rises. I ASSumed the equipment came set up for my system, not so. Surrette specs not programmed in etc.I have been tweaking them and then watching for improvements.Partly Sunny day today here so I'm using that.Thanks again, Stillchillin

cruiser guy · February 2012

Re: Commissioning a new battery bank

I got a question on this as well. I'm about to put in 6 200Ah 12v automotive lead acid batteries as storage for my off-grid system here in Sierra Leone. I'm running a 24vDC battery bank so this will be three groups of two batteries.

Here I believe batteries are simply filled with acid, and generally not too carefully, and sent out the door. What should I do as I go about setting this system up?

As of right now the batteries have not been connected nor have I checked acid level or SG. I can put them on a charger if needed or add electrolyte. Distilled water might be a little harder to come by.

Suggestions so I can do it right from the get go!!

Commissioning a new battery bank

Comments

Categories