Recent loss in charge input

[Vic]

Battery 1:                 
6.68v.                               
Cell 1: 1233.               
Cell 2: 1205.         
Cell 3: 1215.         
.

...   As WB said if you use the IOTA early in the day slash overnight, then the classic will be able to do an EQ in just about any weather. EQ doesnt take much current at all, if its done after an absorb   ...   

For Flooded batteries that really need an EQ,  it usually requires a relatively large current to reach the EQ voltage and  a relatively long time to accomplish a full EQ.   And,  it appears that this battery really needs a charge,  and more than one  EQ cycle.

It is often good to limit the EQ current to about 5% of 20 hour Capacity,  which can extend the time to reach Veq,   and the time required to accomplish as much of an EQ that will benefit the battery.

Hours of bright sun could allow the Classic to produce enough current to reach Veq on a given day,  perhaps,  but it does look like this battery has needed an EQ for some time.

FWIW,   just my experience with FLAs,    Vic

[zoneblue]

Midnite eq occurs without doing absorb first. However some others do the absorb first so it runs  cooler.  Vic, is what you are saying that in a situation like this, getting some energy into the cells is exactly what they need?

[Vic]

Midnite eq occurs without doing absorb first. However some others do the absorb first so it runs  cooler.  Vic, is what you are saying that in a situation like this, getting some energy into the cells is exactly what they need?

The first part of what I was trying to say,  was that it does look like this battery bank really needs an EQ.   This is something that the common Iota Chargers appear to be unable to accomplish for most off-grid systems,  as their EQ happens automatically,  every seven days of applied AC power to its input (as I read it).

And,  in a more indirect way was also trying to say,  that,  given the recent weather conditions at the site,  it seems like the Classic would be unable to "finish" charging the battery and get to the target EQ voltage in any reasonable length of time,  because,  this usually requires a lot of current delivered into the battery,  and usually takes a long time.

YES,  getting the battery fully charged,  soon,  seems very important.  AND performing a meaningful EQ,  perhaps over a period of days looks to be important as well.

I DO realize that the Classic does not require a full Absorb,  prior to an EQ,  and that the Classic does not perform an Absorb as a part of its EQ.   On the systems,  here  we only EQ from PV,  and the Classics are the only CCs online,   so am very familiar with the drill.

The suggestion of limiting EQ current (when the EQ target voltage is approached,  or has been reached)  IS to try to reduce heating,  and also it is said that undesirable compounds can be created in the battery,  if large currents are available in the initial part of the EQ,  as I read it.

Agree with you that the current usually required to finish an EQ is relatively small,  but getting there often requires considerably more current to reach the target voltage,  and naturally this current tapers,  as the EQ does its job.

The subject battery bank is not too old,  and if it has not been deficit-charged for a long time period,  Corrective EQ should not be required.

There are many things about this system that cannot be known at this point.

All FWIW,  and so on.    Vic

[BlackwaterPark]

Wow.  A lot to absorb for sure.  Thanks to all the input, I'm making headway in not repeating the same mistakes for my next bank, and possibly can even resuscitate this one.  The good news is that my bank, at 600 bucks, is a minimal investment compared to the average offgrid bank.  So if nothing else, I'll look at that as the tuition cost to battery maintenance 101.

Thought I might have the chance to EQ this weekend as I'm home all day, but it looks like gray skies and light wintry mix... After a whole week of actual good sun that I couldn't be here to take advantage of.  I'll try it anyway, given that the EQ doesn't require much current as I was just informed. 

So my next step is obviously another set of panels paralleled to the first.  I'm assuming this will help the bank reach these voltages sooner, thus providing for longer and more effective absorb cycles and EQ opportunities?

Also, scrolling though the menu I noticed the "rebulk" setting, which was placed at a valur of 8.  Is that right? What is the rebulk feature?

For the moment, the iota is charging and I disabled the IQ module so that I can run its absorb without hitting the float. In light of the lack of light today, that seems the only sensible route.  Seeing as the SOC reading isn't doing much good, I guess simply monitoring the voltage and temp are my tools to gauge what the batteries are doing.

Thanks so much for all time taken to help me out with this... I suspect it's exhausting reiterating the same concepts time and again to each new person that comes along with the same problems. 

[BlackwaterPark]

So, started the Iota charging at 830, the bank under light load is 24.3v and by 10:45  the voltage has raised to about 27.2 at which point I used the dual voltage jack to get 28.3v input. All the while, the classic is running, but not a whole lot of helpb (V in at about 56v average... Counting the charger). At 11:00 I enable the EQ. Bank Voltage still at 28.3v, temp gauge reads 22°C.  I add some water to each cell... Not a lot, just bringing the levels from about 1/4" to 1/8" from bottom of fill hole. Batteries making occasional glugging noise.   Wait an hour, take SG readings at 12:00 (3 times per cell)... All cells redlined at 1150 or worse (which I'm guessing is because all the water I've added hasn't mixed much and is throwing the reading off?) Bank voltage holds steady at 28.3v still. Input voltage reads ~40v, battery sounds remain occasional glugging as before.
1:30 now, bank voltage still at 28.3, input voltage at 39ish, and so far for the day I've garnered a whole 100 watts of pv input. Iota still charging in its absorb mode, and the Wb is reading 5.8a input from the charger. The voltage input does occasionally spike to 69.ishv for brief seconds though.  SOC reads 100% ( not that that matters much)... Should I just continue to run the charger? It doesn't seem likely that the bank voltage is going to rise higher than the 28.3 it's been at for hours now. EQ is still enabled, but I'm unsure that its doing much of anything ( the classics EQ value is set to 31.0 and its absorb is 28.2). Although the EQ mode is still enabled, the classic appears to be resting.

[Westbranch]

Keep charging...  recovery is a long process...  Think of how long it took to get the batteries in their current state...

[BlackwaterPark]

Thanks WB.  So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.

[zoneblue]

The battery wont reach EQ sort of voltages until bulk is finished.  That will depend on start SOC and charge rate. If the iota is charging at  0.1C and the battery is at say 50%SOC, then it will take 0.5/0.1 * 1.4(ish for charge effciency) hours to charge. In that example thats 7 hours. What i and wb were suggesting was getting the bank to that stage early in the day and letting the classic do the EQ on what little solar you have.  That might mean running the iota over night if the SOC is down a bit. Maybe you need to consider shedding your loads off the system until you get the SGs up to target? If that bank is savable , now is the time to do it.

[zoneblue]

Thanks WB.  So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.

Yes, as soon as the taper reachs a current that youre confident the classic can produce for several hours, then trigger the manual EQ with the classic. You want it to bubble real good. Your new water will mix up and the SG will hopefully come up.

[tecnodave]

Bwp,

I keep a turkey baster in my battery kit, I stir the added water into the acid with it for mixing , and before specific gravity readings.  I have Iota chargers , 2 DLS-55/IQ4 , in series connected with a center tap to the batteries. I do not like the way the Iota's handle eq. so I only let my Classic do the eq. in manual mode,  I keep an eye on it.

Recovery is not easy, it took a month to fully recover my sadly abused Rolls Surette's.  (They sat dead for a year.   0.05 volts for the set)

Hope this helps, battery life is all about maintaince.

Td

[BlackwaterPark]

Thanks WB.  So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.

Yes, as soon as the taper reachs a current that youre confident the classic can produce for several hours, then trigger the manual EQ with the classic. You want it to bubble real good. Your new water will mix up and the SG will hopefully come up.

Zone, that was particularly helpful and instructive.  Thank you.

[Vic]

B w P,

YES,  you really do not want to add water to batteries until they are really in Absorb,  and there is good likelihood that a full Absorb will be completed that day  --  would suggest adding water about half way through a normal Absorb.  The only exception being if you discovered that some cells had the plates partially exposed,  then add water to just cover the plates with a bit more fro good measure,  then place on charge,  and add recommended water level during Absorb.

You are trying to recover your battery bank,  so you should remove all loads on the battery immediately.  It the loads are those on the inverter,  you could possibly run them on the genset while running the Iota.

When you see the input V to the Classic rise for a very short time every few minutes,  this is probably the Classic doing a Sweep,  to fint the Max Power Point  -- this is a good thing.

At  28.3 V battery voltage,  your Flooded batteries are NOT in Absorb,  the Iota may think that IT is in Absorb,  but your batteries are not yet there.

Yes,  you should completely ignore any SOC readings from the WBjr,  it will be most accurate,  when the Classic transitions to Float,  and the SOC will reset to 100%.

The only real measure of the SOC of your battery,  is your Hydrometer,  and adding water when there is not fairly aggressive bubbling,  good mixing of the water into the electrolyte will probably take some time.

Am not too optimistic that the Classic will be able to do much charging or EQing until there are some bright sunny days in succession.

28.2 V  (IIRC, this is what you mentioned as Vabs)  as an Absorb setting on the Classic is really far too low,  at this point.  It makes little difference now,  but such a low setting can make the Classic stop doing any meaningful charging while the Iota is also charging,  and could easily cause the Classic to Rest,  it the Iota causes the battery voltage to rise much above this set value.

Good Luck,   Vic