Is this Surette just doomed to die soon???

Freewilley

I will detail some numbers below for you guys who are kind enough to dig deep....but essentially, one cell in one battery is consistently low. I first noticed this on August 30 when I did a complete SG checkup. Since then I have tried to EQ as much as possible. I am sure there are dozens of hours of EQing that have gone on in those 2.5 weeks. With a lot if EQing I have seen that cell come up as high as 1.235 (temp adjusted) but consistently it runs .40 to .65 less than its neighbors. It is a middle cell, which I generally have found are the ones that run low, if any.
I have been running the generator a lot in the mornings to bring the bank up and then EQd if there was any good solar. Even a week before this low reading this cell was running with the rest.

Right now the problem child is at 1.175 and the rest are around 1.220, after running the generator at  1700 watts charging for a couple of house this am. It is a good solar day so it should get 4-5 hours at EQ of 16.0, which is the best I can hope for at this time of year.
Basically, all I know to do is EQ. Possibly isolate this string, which I have done at times when I find I need lots of EQ time.
In 3 weeks I will shut down the system and head south. I know that when I come back in May I have twice as much solar power (at least) as I do now. The only negative to carrying on the way I am is that I am running the genny twice as much as I would if I were not trying to EQ every sunny day. That is costing me maybe an extra 10-20 bucks a week in gas. If I moved to 2 batteries that are normal, I would save a little gas...
Any thoughts on best course of action? Give up? Divide? Keep pouring in the Genny power? Other?
The batteries are about 2 years old. I have never been happy with them, and I was not happy with the set before which Surette replaced after 2 years.
The problem cell has not lost any water over the last few weeks, while the other 5 cells in that string were wayyy down the other day (I learned a lesson to not just monitor the problem cell but to watch the water levels in the active cells). 

Some details...I have more numbers, but I think this is detailed enough, there were more EQ cycles than the few noted below. I EQ often trying to get the bank up to full power. It never gets to 1.265 if it is not run on EQ
July 31 sgs on bank run 1.210 to 1.255 with problem cell at 1.250
Aug 17 problem cell normal 1.235
Aug. 22 normal 1.225
Aug. 30 problem cell suddenly a problem 1.155, balance are 1.205-1.235
Sept. 2 after 5 hr EQ that day, problem reads 1.225 (temp adjusted)
Sept. 3 after 5,5 hr EQ, problem reads 1.230
Sept. 13 before EQing, problem reads 1.210, balance are 1.240 to 1.260
Sept. 14 3pm problem reads 1.175, balance are 1.210 to 1.220
Sept 15 basically same as above
Sept. 16 basically same as above



 

Vic

Hi Freewiley,

So,  you have two parallel strings of S-550 Surrettes,  believe that these are approximately 420 Ah at the 20 Hr rate.

Your system would appear to be fairly well-balanced,  if the PVs get good sun for a number of hours per day.

With parallel battery strings,  you need to use your Clamp DC Ammeter to measure string current balance during heavy charging/discharge.  Sometimes one needs to separate strings,  and charge/EQ the lowest SG batteries by themselves.

You will need to be very conscious of voltage drops from poor battery jumper connections,  and perhaps dirty terminals.

Lagging cells that will improve SG with numerous EQs,  but are always lower than other cells can often mean that that one cell experienced a very deep discharge,  perhaps,  close to zero volts.  If this is the case,  this cell will never really recover,  even if you could do an EQ on that cell separetly (which,  you really really cannot).

What gauge cable size are the jumpers between the two batteries,  per string?
Have you measured the voltage drops between the CC battery terminals (individually) and the battery?   What are those drops?
Have you measured the voltage at the + and -- 12 V battery terminals when charging from your Inverter/Charger?
What is your Absorb voltage and time?
Are you using the RTS on every charge source?  Is the RTS attached to the side of one battery,  about half-way down the side?
Are the CC and Inverter/Charger Temp Compensation values set to -- 5mV/Cell/degree C?
Are you manually Temperature-Compensating the EQ Voltage?  IMO,  this needs to be done,  as the OB CCs will not do this on their own,  IIRC.
Did you follow the Surrette-recommended Commissioning of the battery bank when it was new?
What was the SG  of this cell,  and terminal voltage of the battery with this cell initially (before Commissioning)?
Are the Date Codes identical for all four batteries?

YES !!  Far too many questions !   Thanks for any answers that you can provide.

FWIW,   Vic

softdown

Just a note on water levels....I have found that healthier cells consume more water than unhealthy cells. You seem to be experiencing this.

Are you able to keep the batteries cool at all? Some battery banks are located in places that exceed 40 C and die prematurely for that reason. Our Canadian friends usually significantly outperform our USA battery longevity because their batteries are stored cooler.

How low are your batteries allowed to discharge to? I'm a huge believer in a 11.5 volt/battery disconnect......23 volts for a 24 volt system. Batteries start to develop sulfide when operating below ~12 volts. Forklift battery longevity is partially due to the week-end equalization charge that likely "knocks off" built up sulfide.

I'm interested in the size of your battery interconnect cabling and quality/cleanliness of the connections. BTW....I am not an expert.

Freewilley

Vic: We have been over my system a couple of years ago. And I went over it with Steve Higgins from Surrette. We never found an issue, except that I do not reach full charge often enough (he wants 3-4 full charges per week....never going to happen). I could never get these 4 batterries up to full charge with running an EQ cycle...and we spent 3 months working on that when they were brand new.

I also have found that strings need to be separated and batteries need to be moved to different strings. I do this every 2 months approx.
My cables are sized ok, they are 4awg and between batteries are only 12 inches long. 

You fellows did strike a chord with me though....in mid-July I noticed that one interconnect was hot. It also was starting to be dirty at the terminal. I could not get a replacement cable so I took one string off to avoid using that bad cable.
I replaced that cable and cleaned all terminals about Aug. 15. No heating since new cable put on, so my tech said cable end was the problem.
It was about 2 weeks later that this problem cell showed itself. The reading was fine four days earlier. So I do not think that problem in July lead to this, but it could be this cell got very low in the week between readings without me knowing it, actually it must have been much lower as my 1.155 reading was taken at noon, when my bank has usually charged up (not sure as I did not note the weather that day).

Softdown: my batteries have occasionally gone as low as 1.155 if I have not been attentive. I watch the resting voltage and the reading does not get below 12.0 but often that is not a true reading so I am often confirming SG readings. My batteries do not run hot and when EQ ing I run a fan and check temps. The max temp I allow is 120 and if I see that I stop the cycle. I find the temps are running hotter now that the Batts are 2 years old and there is definitely more sulphation. 

What I am looking for is advice on what to do now....I only have 3 weeks until I shut this system down. And this is the least amount of solar available...due to trees I now have sun from 10am to 5pm (my panels do manually turn so that is helpful). 
Should I just cut this battery loose (which means lose the string and I work off of 2 S550s) for the next 3 weeks, or forever?
If doing so for the next 3 weeks with the intention of reviving it in May, I would get it as high as possible, but that is probably only to 1.220 SG. Then I would work on EQing the 2 battery string in May and see what happens.
The alternative is to cut down to 2 batteries permanently until they do not work and then go to some other battery...I am done with Surettes after these 4 new ones have been so much trouble. I would not be thrilled with having a third unused battery and know that I cannot throw in a new one with the old....but I could rotate it through the string. I have run for weeks on just 2 batteries and know that I can do that with judicious generator use.

whew...that is all for now....

westbranch

will you just leave the charging system on without loads or will there be  appliances etc that will drain your batteries?

WaterWheel

Keep in mind that that much equalizing is hard on the rest of your batteries.      You may be hurting the rest of your batteries trying to save that one cell.

In my uneducated opinion the fact that after all that equalizing and the cell is not coming up like the other cells and is not using much water the answer is yes, that cell is very weak and will hurt your other batteries if left inline.     The fact that the other cells in that battery are charging properly suggests that the cables are not the problem.

Vic

Hi Freewiley,

Yes do have some recollection of your previous situation,  just did not recall the fine detail.

IMO,  the one battery with the lagging cell is probably toast,  and you should revert to a single string.  Did not check the previous Thread regarding the details of your PV string voltage,  etc,  but am certain that this was covered here,  before,  as well as with Steve Higgins @ Surrette.

It would seem,  that you need quite a bit more PV,  or perhaps you might need to move the PVs,  if significant shading is the main issue.   I do realize that you appear to be in the FAR North,  where the sun angle is becoming quite low,  at Solar Max,  and that shading is probably more pronounced at this time of year.

As was mentioned before,  please DO use the RTS on each charge source.   AND,  believe that neither the MX-60,  nor the FM-60 CC will Temperature Compensate the EQ voltage.   Compensation for EQ is very important,  and perhaps you may need to adjust the Veq downward,  as the EQ progresses.  Temperature Compensation of Absorb and Float voltages is also very important,  especially in relatively harsh climates.

Personally,  am very happy with the Surrettes here  ...  11 years of service,  and counting ...  knock,  ...  knock.   IF Surrette did replace your previous battery bank under warranty,  believe that you did get good service from Surrette.   Still do recommend and specify Surrette Flooded batteries.  Undercharging is about the most common issue with Lead Acid batteries.

Good Luck!   Vic

Freewilley

will you just leave the charging system on without loads or will there be  appliances etc that will drain your batteries?

Answer: I am just turning it all off. I have tried it both ways. I do not see much discharging of the sitting batteries and I think that is because of the very cold temps. I think using the system for 6 months just to keep a charge on the bank is smart....but if my bank worked like it should that would be an option.

Vic....I did not mean to say you should remember me...you help lots of folks!
As far as sun, you would not believe the difference once we hit September! But I am dealing with a small lot and some 60 foot trees around my lot...this only works because we are here for only 6 months.

I am not clear on how I do the RTS on each charge source...

softdown

Any luck with a warranty claim? I would consider replacing that battery. A bad cell can take down connected batteries. I think a short can potentially cause an explosion and fire.

Trees blocking the sun? Could be the real problem right there.

Vic

Hi Freewilley,

The bad cell in that one battery could possibly FREEZE during the Winter.

Did not believe that you were saying the I should have remembered you and your situation,  previously.   But  do recognize your Moniker (name,  or whatever it is called here).

Outback products can share a single RTS among CCs/Inverters,  etc,  but  think that it requires a Hub,  and perhaps a Mate.  Otherwise,  you really should have an RTS for each CC,  and,  ideally on the Inverter as well,  as you are doing a lot of charging from the inverter,  as well.

Too bad about the poor sun situation in late Summer,  but seems like that goes with your location.

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

softdown

Summer equinox is June 23rd. Sun power is, I believe, average this time of year. It is going to decline for ~three months. Then take ~three months to regain the current output.

This time of year should not be the problem with sun production. Maybe you have a different sun?

westbranch

no, just trees that may not be his to dispatch, sounds like what is known as Cottage COUNTRY in Eastern Canada

softdown

I seem to recall partial shade wreaking havoc with solar production. If part of a panel is covered, that essentially shorts out the panel?

westbranch

and that is when series connected panels are beat out by parallel wired arrays....  and that means bigger conductors are needed if the PVs have to be far away from the CC and batteries.

BenA

Freewilley said:

Aug. 30 problem cell suddenly a problem 1.155, balance are 1.205-1.235



Would it help to drain/refill the weak cell with fresh battery acid and put it on a desulfating/maintainer at about 1.5 amps or so for a week plus?







 

BB.

It is supposed to be a bad idea to change out with new electrolyte.

I guess the question is where did the sulfur in the electrolyte go? It can only go into the lead plates, unless there was "dirty" water used instead of distilled water???

-Bill

Freewilley

Thanks to all for your concerns....
Vic: Now I get what you meant by RTS for each charging source (duh!). So I just went over to see where it is connected and it is not!
I had some rewiring done by a "pro" who was a goof and he disconnected it from my MX without telling me and I just never noticed the end was not connected where I had it previously. Until today.
And what effect has this been having, not having RTS at all?
Very interested in that....
Nobody ever mentioned a HUB before. I just went and looked it up and will order one. Right now my Mate is connected to my inverter and nothing else. I will install the hub and connect up my devices. 
What will change once the mate talks to the Inverter PLUS the two CCs? How much is this responsible for my battery issues?

Man I wish there was a decent tech near me! I never anticipated having to become an electrical engineer when I went solar!

And yes, that low cell is more likely to freeze. I should try to get the sg up as high as possible..but I think that battery is a boat anchor anyway. I have disconnected that string which gives me one odd man battery which I will cycle through other string. 

Softdown...on solar and using this date for "average". You are no doubt correct, but average for the calendar year is not the same as average for my solar use, which is May 10 to Oct. 10. And yes, it is very affected by trees which I cannot cut down. Not nearly so affected in the first 1/2 of my season, May to mid August.
I compensate by having 4 different panel locations, 5 of 7 panels rotate to maximize and 2 are on roof to avoid shade. It is what it is....and the generator is there to top up. At this time of year I run the genny for 2 hours for coffee, breakfast, clotheswasher. Often at night over the supper time. It really does not take that much juice as the genny is running at partail load. With 2 batts connected I charge at max of 900 watts.
I only use clean distilled water to refill cells. 

As far as warranty...even if I get a new battery for reduced cost, I know it is not a good idea to mix that in my bank of 3 two year olds.

softdown

The older batteries will endeavor to bring the new battery down to their level of performance. It isn't like a new battery is going to hurt the string like your current battery is doing.

Your panel set up makes my head hurt a little.....ouch.

BB.

Not having RTS will mean (usually) a lower than desired charging voltage (on average). Basically, most charge controllers run a bit "hot" (electronics) and average hotter than the battery bank. And you can end up with slower charging (lower charging set point) and possibly under charging your battery bank ("wasted" solar energy, when "hotter" controller cuts back on charging voltage and current to the "colder" battery bank).

In worst case situation, high charging current (and high charging voltage set points) cause the battery banks to heat up. A hot lead acid battery bank wants a lower charging voltage--So it is possible to "cook" the battery battery bank in this example.

You might check with your local battery supplier and see if anyone has an "orphan" battery from their bank.

Getting one "new battery" to replace the failing one--If you need the disconnected string's capacity--Go ahead.Just assume you will probably "junk" the new battery when the rest of the bank eventually wears out. It would not be worth keeping it unless you are willing to keep it charged (at least 24 hours of charging once per month).

-Bill

softdown

FWIW....thought you folks might find this interesting. I live in one of the coldest areas in Colorado so it is easy to keep batteries cool. If an owner can keep stored batteries below 60 F, the maintenance rate goes down significantly. I would think "the cooler the better" in fact....assuming the batteries have close to a full charge.

Ralph Day

I had 2 2volt cells replaced under pro-rated warranty by Surrette.  The bank is over 12 years old now, I replaced the cells at the 7 year mark.  Their sg is significantly higher than all the other cells.  Full charge for all 1.265, for the replacements 1.285.  Maybe the electrolyte formulation changed over the years.

Adding a new cell or batery after only 2 years would not be a problem in my opinion.  You'll have it drawn down to the capacity characteristics of the rest, but so what?  You;ll still get the rest of the life out of the system for a lot less cost than buying all new to keep the ages the same.

I still have a couple of lagging cells show up now and then (2 at present).  Lagging to me is  .02 to .04 below the rest fully charged.  Not really problem cells like you've got.  I built a single cell (2v) charger to augment what the whole system charges the batteries with.  It required putting lag bolts through the top case so they touch the cell interconnects.  Clip the leads on the pos and neg and you can add current to just one cell in the battery.  Of course, you have 2 more possible contact points (dropped wrench or whatever), so care must be taken working on the bank.  I charge the extra charger while the system is on absorb or float usually.  This keeps the laggers up to charge, or closer to full charge.

ralph

Freewilley

Interesting comments. Shade does not completely take out a panel...I have a string wired each way and they were producing a little power even though mostly shaded this morning.
My bank does not run hot. One reason is that it is in the basement so is kept cool for most of my season, usually in the 60s.
But when I am EQing and the temp IS high, over 100, what is that doing to my charging I wonder....although the charging is not cut back becasue the batteries do boil and go as high as 120....

Sounds like I should get a new battery when I come back. I will contact Surette about a warranty replacement.

I will order a hub. My Mate is 30 feet from the bank (near the kitchen so I can monitor things) so I assume the one cable that runs right now from the inverter to the Mate will just plug into the hub, and then 4 connections ...
1. rts (or does it go into inverter?) Probably the Mate goes here?
2. fm60 
3. mx60
4. inverter

Is that right? I need to order cables....

Vic

Hi Freewilley,

Have been in transit,  and am a couple of days behind on this Discussion ...

Believe that it could be less expensive for you to possibly just buy one or two additional Outback RTSes.   The MX and FM CC probably did have RTSes included ...  perhaps not the FM,  do not know.

But,  seems to me that you could avoid using the Hub,  if you do not plan to add any additional OB chargers,  that just buying one RTS for the Inverter/Charger ($25.00 U$D,  plus shipping),  and you may be "good to go".   Link to the Wind-Sun listing for the OB RTS:
https://www.solar-electric.com/rts.html

Have never configured a fully-featured OB system,  so do not really know what else the Hub with your Mate might be able to do together,  other than share a single RTS ...  others will know more than I about that.

If you choose to add an/some RTS/RTSes,  just place ALL of them on the same battery.  With a large string imbalance,  if can be a bit difficult to know just which battery is the best candidate for the RTSes.

One additional note;    As noted,  using RTSes on each charge source is very important,  and could help reduce the risk of Thermal Runaway with hot batteries,  and reduce the tendency for batteries to be "overcharged" when warm/hot.   ALSO,  the RTS is very important to help ensure fully charging batteries that are cool/cold (it will tell the CC/Charger to increase the Vabs,  and Vflt),  thus helping to ensure fully charging batteries that are below the Reference Temperature of 25 C.

Not having an RTS for both of your CCs could have helped contribute to some of the issues with the single "bad" cell ...

FWIW,   Vic

Freewilley

I am very interested to know if having the Mate and CCs linked would have any affect on my system....anyone help on the that concept?

If not, I guess I need 2 more RTS so that both CC are in tune....and put the one I have in the inverter. That is more than $100 cheaper than the hub. But I would spend the money if it allows them to work better together although I do not really see what they will do differently.

Vic

Freewilley,

I cannot tell you if there are any added benefits of the Hub,  in your system.  Or,  even if  you were planning to enlarge the system with an additional OB Inverter/Charger,  etc,  still do not know if there might be some benefit.  Any of this is really beyond my knowledge and experience.

Forget if you have joined the Outback Forum,  you could ask there,  but know you are on a mission:
http://www.outbackpower.com/forum/

Also,  you could e-mail,  or telephone OB Tech Services.   Sorry,  just cannot give any definitive answer.

Vic 

Saipro

BB. said:

It is supposed to be a bad idea to change out with new electrolyte.

I guess the question is where did the sulfur in the electrolyte go? It can only go into the lead plates, unless there was "dirty" water used instead of distilled water???

-Bill

I have a setup with this very same problem. The difference is mine consists of a single string of Trojan T105-RE 6V baterries x 8 for a 48V bank. The one at the negative terminal has an obviously bad middle cell (doesn't bubble like the others). Recently, I noticed a rapid about 4V drop (instead of the previous about 2V drop). I discovered from SG readings that it's the cell at the negative terminal. That's 2 cells now. The last cell consequently bubbles vigorously when approaching the end of an absorb cycle. Two questions:

1. Can I keep running the bank with this obviously bad battery in situ? It reads a little less than the others (the difference being a little higher voltage in the other batteries during charging) without eventually damning the entire bank?

2. I've noticed my inverter runs fine on just 7 batteries and complains only when I'm running heavvy loads at night but I've never gone below the 70% charge limit (which registers as 26 - 28% on the 7 battery bank). I did configure the Midnite Classic charge controller to charge a 42V bank instead of 48V. Is this alright.

Then a quick third question (request for advice): of the two scenarios above, which would be recommended to go with?

BB.

If the bank is otherwise in good condition (and not near end of life itself), then buy a replacement battery (or see if you can get a good used battery--Craig's List apparently does not allow battery listings).

I would not suggest leaving bad cells in the string. It is possible that you can overheat the bad cells (or possibly the good cells during charging--Depends on what is exactly is happening).

With bad cell(s), you run the risk of over/under charging other cells. If you can run the bank without the bad cell(s), and set the charging voltages appropriately--I guess why not for a short term fix.

And keep an eye on battery temperatures. It is possible to have a catastrophic battery failure if things are left too long before fixing.

-Bill

Saipro

I wholly agree with you on all your points. Two problems:
1. The overheating/overcharging issue has begun manifesting albeit in a barely noticeable manner. The bank is barely two years old thus way too young to junk. Besides, the other batteries have just hit their prime.
2. Getting a replacement used battery is out of the question due to unavailabity.

Can I just go with the 7-string 44V bank until the bank gives out? Any foreseeable problem with that (asides my inverter occassionally "erroneously" sensing a drained bank)? I'd rather just run with the 7-string formation, if acceptable

Dave Angelini

Why can't you buy a new GC battery?  

Saipro

I'm in Nigeria and the economy is being hit by possibly the worst recession ever. On the parallel market, the dollar has gained god-like value against the weakening naira. Importers are biting their nails as there's a good chance no one would shell out four times the initial price value for a replacements or otherwise. Since I bought these GCs in February 2015, I assure, no other Trojan GCs have come in commercially. I simply don't have access to replacements.

So, can I survive on the 7-string bank without damaging anything (the Midnite Classic 150 is a beauty to programme)?

Dave Angelini

If your inverter has a low voltage cut-out that is adjustable enough. Otherwise it will be struggle.  Good Luck!