Your thoughts and help will be appreciated:
I am having a hard time getting my SW 4024 to finish a charge for my Trojan L16 435 amp hour batteries (x4 in series) . I get to an SG of 1.266-76 (depending on the cell) and the Classic says I am at 99% SOC with only 433 amp hours. Trojan says 100% is 1.277 and when I did an EQ last week, I noted the SG in all cells stopped rising between 1.286 and 1.295 according to my Hydro, so I took the average of those hi numbers and have tried to use that as a target for 100% charged (because my hydro may be off).
I have raised the Absorb timer to max so it is not timing out ... and have raised the Absorb voltage to 31.2 and temp comp to -5 (so today they were charging at 31.5 +/-). That is getting near EQ voltage. :o
I Found this thread (http://midniteftp.com/forum/index.php?topic=3577.msg38551#msg38551) and read most of it .... I noticed the OP has an Schneider Conext SW Inverter/Charger. So I asked there too.
But I am wondering, the Schneider Conext SW 4024 does not have an end amp setting like the Classic. BUT it does ask for the Battery Bank Capacity in Amp Hours. I cannot see a reason why the SW would need to "know" the amp hours (it does not report SOC) except to set End Amps. I did kinda confirm that is the case noting that the charge seemed to kick to float from absorb at about 8.7 amps which equals 435 ah x 2%. So I tried setting the AH in the SW to 100 and it ended at about 4.5 amps. But the batteries were already about 99% charged.
What is the best way to get my SG to rise on up to my Base Line of about 1.288 (on my hydro) that I establish using an EQ until the SG stopped rising? Should I continue to raise the Absorb Volts? The SW also has bulk volt setting. Should that be the same as the Absorb setting? I set it lower so I do not over gas the batteries.
Thoughts? Thanks.
Mike
I guess I am not following you .
So you are using the equalize SG to base your 100% full SG on instead of the manufacturer recommened SG which is lower ?
An equalize charge is an overcharge . Doing that continually is not good for the lifespan of the batteries.
What are the SOC settings you have in the Classic ? Those are probably what is keeping it from showing 100% . You can change the efficiency setting on that if you need to get it to read 100% . The SOC is just an estimate gauge not a real perfect gauge.
Larry
Mike,
YES, Schneider CCs and many of their inverters use a FIXED 2% of the battery Capacity that has been entered as the EA value -- Schneider programmers (the humans) seem to be a very non-creative lot. SO, anything that they can force the user do calculate and enter into their hardware, they do gleefully, with a chuckle.
So one is forced to lie to their hardware about the Capacity of the battery, to change the value of this dim-witted EA function (IMO).
IIRC, you are using a Hydrovolt (?). Which should be temperature compensated for its readings. If so, it might be possible that it could take a bit of time for the compensated to show up.
Had asked before, if you have been using the procedure for measuring SG that had been Linked -- Surrette's Measuring Specific Gravities. Believe that Trojan has a similar one ... the method one uses to take SGs DOES matter. Have you read either of these, and are you doing as suggested?
Do you RINSE, Rinse, and RINSE again after EACH SG measuring session ??
Also, some variation in SGs, cell-to-cell, can be attributed to some variation in battery temperatures, and in electrolyte levels, but, neither of these should be very large factors.
With a very good Hydro, about the best repeatability is 5 points, and that does not include Calibration error.
Also, it is often recommended that one measures SGs while the battery is being Floated, several hours after the end of an Absorption or EQ charge.
Your batteries should have stabilized now, as they probably have more than about 75-ish cycles.
One other thing, is, if you have significant Opportunity Loads on your system, when approaching your EA setting, even small voltage drops in connecting cables (and even breakers), can have a relatively large effect on the duration of Absorb, when using EA. This is the result of a voltage drop in cables/breakers lowering the charge voltage at the battery terminals, compared to what the CC believes is the voltage, thus reducing battery charge current in Absorb, and causing early Absorb termination (for CCs without battery voltage Sense terminals/leads).
Just a drive-by, FWIW, Vic
Quote from: ClassicCrazy on January 13, 2018, 05:20:14 PM
I guess I am not following you .
So you are using the equalize SG to base your 100% full SG on instead of the manufacturer recommened SG which is lower ?
An equalize charge is an overcharge . Doing that continually is not good for the lifespan of the batteries.
Larry, You are more or less correct. But this is what I am being told on another forum. Set a baseline and charge to that.
I am understanding that 100% SG is the number at which SG stops rising. If this is not true, Are you saying that SG can go higher than 100%? That is, if my Hydro is accurate, and the manufacture says full is 1.277 ... then any number over that is over charged, and that it is possible to have higher SG numbers than 100%?
I was watching carefully the number at which SG stopped rising and using that number (for the past few days) thinking perhaps my Hydrovolt is off and low.
As of yet, in 3 months i have not had to add any water to the batteries. Even with 4-5 EQ charge sessions.
Quote from: ClassicCrazy on January 13, 2018, 05:20:14 PM
What are the SOC settings you have in the Classic ? Those are probably what is keeping it from showing 100% . You can change the efficiency setting on that if you need to get it to read 100% . The SOC is just an estimate gauge not a real perfect gauge.
Larry
Where are the SOC settings? Is that the battery efficiency setting in the Local App? Battery Efficiency is set to 94%
Quote from: Vic on January 13, 2018, 06:58:35 PM
Mike,
YES, Schneider CCs and many of their inverters use a FIXED 2% of the battery Capacity that has been entered as the EA value -- Schneider programmers (the humans) seem to be a very non-creative lot. SO, anything that they can force the user do calculate and enter into their hardware, they do gleefully, with a chuckle.
So one is forced to lie to their hardware about the Capacity of the battery, to change the value of this dim-witted EA function (IMO).
Yes ... that is what I have found. I am not impress with Schneider, find that the SW does not work as advertised, and if I could do it all again, I would run far far away from Schneider products. (But I bet the B17-3 is going to be over my pay grade :-\ ... but it looks cool)
So am I correct. The best way to control End Amps in the SW would be to change the Battery Capacity function?
Quote from: Vic on January 13, 2018, 06:58:35 PM
IIRC, you are using a Hydrovolt (?). Which should be temperature compensated for its readings. If so, it might be possible that it could take a bit of time for the compensated to show up.
Had asked before, if you have been using the procedure for measuring SG that had been Linked -- Surrette's Measuring Specific Gravities. Believe that Trojan has a similar one ... the method one uses to take SGs DOES matter. Have you read either of these, and are you doing as suggested?
Do you RINSE, Rinse, and RINSE again after EACH SG measuring session ??
Yes to all
Quote from: Vic on January 13, 2018, 06:58:35 PM
Also, some variation in SGs, cell-to-cell, can be attributed to some variation in battery temperatures, and in electrolyte levels, but, neither of these should be very large factors.
With a very good Hydro, about the best repeatability is 5 points, and that does not include Calibration error.
Also, it is often recommended that one measures SGs while the battery is being Floated, several hours after the end of an Absorption or EQ charge.
The 2nd Hydrovolt I received seems to be very accurate at least to itself. It seems to get repeatbable numbers in the same cell after the 3 draws from each cell. It is consistently 7 points higher than my glass Hydro, which is why I am targeting 1.285 instead of 1.277. But you are right. I do need to wait a bit after EQ to take a final reading.
Quote from: Vic on January 13, 2018, 06:58:35 PM
Your batteries should have stabilized now, as they probably have more than about 75-ish cycles.
One other thing, is, if you have significant Opportunity Loads on your system, when approaching your EA setting, even small voltage drops in connecting cables (and even breakers), can have a relatively large effect on the duration of Absorb, when using EA. This is the result of a voltage drop in cables/breakers lowering the charge voltage at the battery terminals, compared to what the CC believes is the voltage, thus reducing battery charge current in Absorb, and causing early Absorb termination (for CCs without battery voltage Sense terminals/leads).
Just a drive-by, FWIW, Vic
Thanks.
Again, my main question was charging with the SW and if I should continue to raise the absorb volts ... or if lowering the Battery capacity would cause a longer End Amp charge. Seems the lower capacity "Cheat" might be the better way to go. Using an absorb of 31.3v today ... the SW kicked off into float while the batteries where at 1.265 on the Hydrovolt. Even if the Hydro is accurate to a T, that is still too low.
The way I understand it, EA shouldn't be used ALL the time... i.e. you will need to do a timed absorb (2 or 3 or 4 hours ?) once per week or
so. This is to desulfate the plates and get the sulfuric acid back in solution. The more it sticks to the plates, the lower the SG will be able to get.
If the batteries are not disharged, then the Ending Amps will stop the charge without having to go the 2 or 3 hours to do a good
anti-sulfation. This is what the skip-days feature is supposed to do. But I think it can work better with the EA and be a bit smarter.
The battery can be recharged back to 100% by putting back the amp-hours taken out plus the AH inefficiency (extra 5% to 10% usually)
Absorbing or EQing for a "long enough" time should ensure that the battery has gotten a FULL @^# charge (Anti-Sulfation-Stage)
Then, the State Of Charge should assume to be 100% of whatever the capacity actually is. Might be better, might be worse than the
label rating of the battery.
This is how I understand it anyway.
boB
Quote from: Matrix on January 13, 2018, 09:34:55 PM
Quote from: ClassicCrazy on January 13, 2018, 05:20:14 PM
I guess I am not following you .
So you are using the equalize SG to base your 100% full SG on instead of the manufacturer recommened SG which is lower ?
An equalize charge is an overcharge . Doing that continually is not good for the lifespan of the batteries.
Larry, You are more or less correct. But this is what I am being told on another forum. Set a baseline and charge to that.
I am understanding that 100% SG is the number at which SG stops rising. If this is not true, Are you saying that SG can go higher than 100%? That is, if my Hydro is accurate, and the manufacture says full is 1.277 ... then any number over that is over charged, and that it is possible to have higher SG numbers than 100%?
I was watching carefully the number at which SG stopped rising and using that number (for the past few days) thinking perhaps my Hydrovolt is off and low.
As of yet, in 3 months i have not had to add any water to the batteries. Even with 4-5 EQ charge sessions.
Quote from: ClassicCrazy on January 13, 2018, 05:20:14 PM
What are the SOC settings you have in the Classic ? Those are probably what is keeping it from showing 100% . You can change the efficiency setting on that if you need to get it to read 100% . The SOC is just an estimate gauge not a real perfect gauge.
Larry
Where are the SOC settings? Is that the battery efficiency setting in the Local App? Battery Efficiency is set to 94%
I think I remember a battery dealer telling me that some battery manufacturers run the SG hot ( too high ) to get increased claims of battery capacity at the expense of battery longevity . Not sure if I have that exactly correct but the point was that it wasn't good to run the SG too high . If you look at specs many manufacturers give a range of absorb voltages and this would correlate to the SG going higher if it is over charged. The way I see it is with new batteries to run the bottom of the range and then raise it as needed over the years to compensate for aging of the batteries or other factors.
hey my memory was correct ! just found this " Some manufacturers use specific gravities as high as 1.320 in an attempt to gain additional Ah capacity, but at the cost of a shorter cycle life. " also nice interpretive graph of what Bob was mentioning about SG changes http://giantbatteryco.com/GLOSSARY/Specific.Gravity-Industrial.Batteries.html
Larry
So there is a hi number I Could go to ... but shouldn't necessarily go that hi ? Correct? Better to stay closer to the Manufacture printed 100% full SG regardless of it the SG can go higher? OK
So what if I am getting say an average of 1.285 from the 3 cells in on battey, But the other 3 batteries and 9 cells are all closer to 1.270. Do I charge until the lowest cell of the 12 hits 1.277? (that is going to put my highest cell up to about 1.292) ...OR... do I average the cells and shut for that number in the highest cell?
Right now today, we have had full sun all day in NE Florida. I was down to 79% and charging stared at about 9am and went thru to 1:15pm when absorb stopped with a about 3,500 Watts going back into the battery bank. So I am seeing it got a good charge. SG on my known lowest cell was 1.278 and on the known highest cell was 1.292. Did I charge too long?
Quote from: boB on January 13, 2018, 11:49:56 PM
The way I understand it, EA shouldn't be used ALL the time... i.e. you will need to do a timed absorb (2 or 3 or 4 hours ?) once per week or
so. This is to desulfate the plates and get the sulfuric acid back in solution. The more it sticks to the plates, the lower the SG will be able to get.
boB
Why would using End Amp not allow for Desulfating of the plates?
Thanks for the Link Larry. Good Read.
What I have been trying to do with my SW charger, while not allowing the solar array to charge the batteries and not using any load (except the load that is draw for the inverter of about 38 Watts) ... I've been trying to establish a base line for charging and for comparing in the future.
Something I read in the Article you posted ....
Quote"The specific gravity decreases during the discharging of a battery to a value near that of pure water and it increases during a recharge. The battery is considered fully charged when specific gravity reaches its highest possible value."
And
Quote"To avoid erroneous readings, specific gravity measurements should only be taken after an equalizing charge and subsequent float charge for at least 72 hours. "
How does one determine the "highest possible Value" of SG? Based on the next statement, I guess I erroneously consider that value to be the point at which the batteries stopped rising in SG during an EQ charge. Looks more like that value is set after an EQ and subsequent Float (the step I was leaving out)
I am trying to get an SG value on my hydrometer that represents a full charge of my batteries using my hydrometer realizing that my hydro may not be exact, but at least if it is consistent, it will be correct ... what ever that value is.
I don't think you are going to be able to accomplish what you want with the precision you are trying to get unless you had a whole bunch of batteries and tested and picked the ones that were all balanced. That might not even exist. Like Bob said the inner and outer cells can vary because of temperature or other factors.
I guess I would go with the manufacturers SG and make sure you bring the lowest SG cells to that point and then don't worry about the ones that are higher SG readings you found. With a good absorb every ten days to mix up the electrolyte and equalization every month you are probably going to do the best you can . The only other option was to do it like Ross said in different post is to monitor each cell ( which you can't do with 6v batteries ) and balance the voltage on each cell like he said he does.
Larry
Quote from: Matrix on January 14, 2018, 01:41:27 PM
Quote from: boB on January 13, 2018, 11:49:56 PM
The way I understand it, EA shouldn't be used ALL the time... i.e. you will need to do a timed absorb (2 or 3 or 4 hours ?) once per week or
so. This is to desulfate the plates and get the sulfuric acid back in solution. The more it sticks to the plates, the lower the SG will be able to get.
boB
Why would using End Amp not allow for Desulfating of the plates?
Because enough time may not have passed for the high voltage to do its job in that regard. This would be because
if the batteries are always charged when the bulk/absorb cycle happens, the charge current will quickly fall below EA
instead of taking a long time. This is what I have understood from the forklift and industrial battery folks. This also
makes sense to me.
I think that what happens is that as the sulfation is allowed to sit on the plates, as it would do if NO absorb or EQ
were happening, then it tends to harden on the plates and will not easily return to the liquid between the plates.
When that happens, the SG will be lower than it was when the batteries were new because the electrolyte will
be more water than Hâ,,SOâ,,,
One could add more acid to the mix and the SG should go up again but that won't fix the insulation on the plates
caused by the hardened sulfation. Someone can adjust and correct my interpretation of all this but I think
that's it. This would be a good one for Steve Higgins from Rolls batteries if he is on here.
boB
Thanks boB ... so if I'm using the Local App, how do I turn EA off? Do I ...
- Simply uncheck the WBJ box?
- or do I lower EA to Zero (0)?
- or some other method I have missed.
Quote from: Matrix on January 15, 2018, 02:03:19 PM
Thanks boB ... so if I'm using the Local App, how do I turn EA off? Do I ...
- Simply uncheck the WBJ box?
- or do I lower EA to Zero (0)?
- or some other method I have missed.
Just turn the EA to zero (0.0) amps
You want the WB Jr. on for state of charge
boB
Crap just lost a long post ...
Matrix asked "So am I correct. The best way to control End Amps in the SW would be to change the Battery Capacity function? "
YES, you are correct.
Deep Cycle batteries are designed to be CYCLED, try cycling your bank to 60, or even 50% SOC every few weeks or once per month.
Avoid charging your batteries when the measured SOC is above 90%.
Both of the above should help reduce the occurrence of SG readings above manufacturer's spec for 100% SOC.
OK on the Hydrovolt, that should do well.
While charging your batts from the SW, during Bulk, measure the battery terminal voltage at the batteries, where the inverter leads connect -- measure on the terminals, not the lugs of the cables. Does this agree with what the SW's voltage?
YES, battery manufacturers increase the electrolyte SG, primarily to increase the Capacity of the battery. A 15 point nominal increase will increase the Capacity by about 5% for FLAs.
AND, have ALWAYS used EA to end Absorb on all systems here (even with CCs that used only the CC's internal Shunt). This has always worked well.
We use WBjr EA, in conjunction with Skip Days on all of these systems, as well.
However, when choosing an EA value, one must not just use the suggested value from the battery mfg. Choose one that works for your system, based on measured SGs, and change the EA for your systems.
In addition, the DOD of the battery in the previous cycle, will affect the correct EA value (YES, this is a bit unfortunate).
If the Vabs is changed, usually, the EA value will need to be changed to match.
As FLA batts age, generally, the Vabs will need to be increased, and the EA will also usually need to change, as well.
AND, battery monitoring devices are only as accurate as are the data entered into them by the user. FLA batteries have a charge Efficiency of about 85% when new. This will decrease as the batteries age.
There are many variables involved in trying to determine the SOC of a battery based on things that can be easily measured, and potentially every battery bank may well behave differently in these factors based on just how it has been discharged, and charged, its age, and so fourth. Battery monitoring devices simply cannot know enough about the behavior of the bank, based upon many of these variables, so absolute accuracy suffers.
SO, battery monitoring devices simply report approximations on SOC, Remaining Capacity, etc. AND, the larger the number of days since the last real full-charge, the less accuracy they will have for the values reported.
If one is reading the battery monitor display, and it says 67% SOC, then it is probably best to think of this as, approximately, or about 60 or 70% SOC ...
Not to put too fine a point on it. FWIW, VIc
QuoteCrap just lost a long post ...
Yes I hate it when that happens.
QuoteIf one is reading the battery monitor display, and it says 67% SOC, then it is probably best to think of this as, approximately, or about 60 or 70% SOC ...
Not to put too fine a point on it.
That is how i see the devices, only a vague generalization of SOC. I am trying to rely on SG as the standard and trying to establish just what that standard is for my batteries, while I actually learn the behavior of my batteries AND FLA batteries in general.
I hear you saying, EA is not really a set point, or an exact % of AH for a given battery bank, but rather something that is more subjective based on Age, SOC, and User use of the batteries? I read somewhere it was 2-3% of AH. That has not worked at all for me yet.
At this point I am going to try a low ... very low End Amp Setting AND try lowering my Absorb voltage for the classic. I was doing that today from a 57% DOD and a day of full no cloud sun. The batteries got a load of good charge, but at the 97% monitor reading, the SG was still only 1.260 on my lowest cell. Or really about 90% according to SG. Absorb was "volting" along at 30.3v (with some mild temp comp thrown in) and WBJ amps were at about 2. I saw the writing on the wall, If I wanted anywhere near full, i had better bump my absorb voltage up because I only had about an hour of solar left in the day. So bumped it up to 31.2v. Solar charge time is done for the day, and the best I got was 1.265. So not fully charged. But the SOC says its at 100% .... so I guess i adjust my battery efficiency % down from 94% to about 90%??
I am going to finish up the Charge with the SW, and set the float on the SW to the Manufacture absorb of 29.6v and let it run for about 3 hours checking the SG later this evening. That should top me off. And since tomorrow is forecast for another clear day, I'll start again with the classic from about 70% DOD , and see if I get the settings where it all seems rights.
Contrary to what you all may think, I am getting a really good understanding of all this. And I thank you all for your help, and MidNite for providing the forum for discussion. So the good news is ... maybe my 1st set of FLA batteries will last a good long time, despite what I have read about the first set being the learner set. That is my hope anyway.
Matrix mentioned, " ... Absorb was "volting" along at 30.3v (with some mild temp comp thrown in) and WBJ amps were at about 2 ..."
It is quite surprising that you are running that high Vabs, and see the battery charge current at about 2 Amps. This would imply to me, that the batteries were fully-charged -- this is less than 0.5% of advertised Capacity.
So, based on SG measurements, what is the average DOD of the battery when charging begins?
When the main battery banks here were younger, with fairly light discharges, the customary EA setting ran between about 0.8 and 0.9% of C, with fairly low Vabs settings.
Now, with the main banks in their thirteenth year, the Vabs settings are higher, and the nominal EAs are running at about 1.6 % or original C.
And, YES Matrix, you are definitely paying close attention to your batteries and the rest of the system.
How about trying to cycle the battery bank more deeply, perhaps by Skipping Days on the Classic?
More later, Vic
Thanks for the quick response.
QuoteIt is quite surprising that you are running that high Vabs, and see the battery charge current at about 2 Amps. This would imply to me, that the batteries were fully-charged -- this is less than 0.5% of advertised Capacity.
I have always had to run the Vabs that hi to get anywhere near 1.277 for an SG or the Absorb would kick out go into float and leave me at about 1.240. It may have been my EA setting. So that is why i have been tinkering with that the past 4 days (and what prompted this thread for both the SW and Classic)
The SOC this morning was 57% (or 43% DOD). Charging began slightly by 9am was was in full by 10. Ended bulk at about 11:50 and absorb ran until 3pm until I kicked it up from 30.3v to 31.2v because the SG was only reading 1.260. But yes ... but 3pm the amps in absorb were at 2.5amps.
QuoteSo, based on SG measurements, what is the average DOD of the battery when charging begins?
I usually use between 20-40% daily
QuoteHow about trying to cycle the battery bank more deeply, perhaps by Skipping Days on the Classic?
Yes I probably need to do some more deep cycling. Because today was clear, that was the plan for today. That is why I ran them down to an SOC of 57% according to the WBJ not the SG.
Here is the My Midnite from today from about 7:15 to about 5pm. 11:50am is where the battery volts (gold) peaked and leveled off at 30.3 going into absorb in about the middle of the chart. The spike of power (blue) later in the day is where my waterheater diversion came on based on SOC of 97%. I turned it off at about 3:15pm after I realized I was not going to get a full charge based on SG. That is when I bummped the Absorb volts up to 31.3v because the SG was only reading 1.260. At that point the CC went into Bulk for the rest of the day. You can see that bump in volts and amps at about 3:30pm. The CC never did go into Float today. Sorry I cannot post the hour by hour in the chart.
I finished this charge cycle day with my lowest cell ending at 1.266 SG. So not fully charged if the lowest cell should be at at least 1.277 ... that is if I am to go by SG.
I don't get this
"The SOC this morning was 57% (or 43% DOD). Charging began slightly by 9am was was in full by 10. Ended bulk at about 11:50 and absorb ran until 3pm until I kicked it up from 30.3v to 31.2v because the SG was only reading 1.260. But yes ... but 3pm the amps in absorb were at 2.5amps."
If batteries were full at 10 am absorb ran until 3pm ?
Your ending amps from your graph should be where the whiz bang amps line starts to level off - that should be your 100% full SOC and when it goes to Float.
Larry
Quote from: ClassicCrazy on January 15, 2018, 07:14:55 PM
I don't get this
"The SOC this morning was 57% (or 43% DOD). Charging began slightly by 9am was was in full by 10. Ended bulk at about 11:50 and absorb ran until 3pm until I kicked it up from 30.3v to 31.2v because the SG was only reading 1.260. But yes ... but 3pm the amps in absorb were at 2.5amps."
If batteries were full at 10 am absorb ran until 3pm ?
Your ending amps from your graph should be where the whiz bang amps line starts to level off - that should be your 100% full SOC and when it goes to Float.
Larry
Larry ... Perhaps I stated it wrong. Charging switched over from Bulk to Absorb at 11:50am and the bank stayed in absorb from 11:50am until 3ish pm.
You are correct that the end amp setting from the graph was where it leveled off at about 4.5-5 amps ... and I have set it there before. But if I set it there, i never seem to get a full SG to 1.277 unless I set absorb volts to 31.5v or more. And that seems very hi. So I had been experimenting with NO end amps to see if the battery actually got "full" using 30.2v as my absorb. But 3pm they were still only at 1.260 or 90% SG. So I increased the Absorb amps and continued charging.
I realize that a leveling off of the amps at around 3-5 amps (as shown in the graph) should indicate full ... but what do I do if that is happening, but the SG is still not reading Full? It was at 1.260 instead of 1.277. In this case I increased the volts for absorb and continued to charge for the remainder of the day which was about an hour and some change. Is this not the right thing to do? I thought SG was the "Gold Standard" for indicating 100% charge.
Quote from: Matrix on January 15, 2018, 08:00:41 PM
... I realize that a leveling off of the amps at around 3-5 amps (as shown in the graph) should indicate full ... but what do I do if that is happening, but the SG is still not reading Full? It was at 1.260 instead of 1.277. In this case I increased the volts for absorb and continued to charge for the remainder of the day which was about an hour and some change. Is this not the right thing to do? I thought SG was the "Gold Standard" for indicating 100% charge.
The time-line on the graph is not shown ...
When did you make the SG measurements that did show SGs at about 1.260 (how long AFTER the Classic had gone Float were those SGs taken)?
What was the charge stage at that time?
What caused the battery voltage to drop, the WB current to go negative in the center part of the Diversion area (heavy extra load) ??
Thanks, Vic
Those batteries are mass produced consumer goods - not precision scientific calibrated grade devices.
Seems like you are trying to make them into something that they are not. There are so many intricacies to the chemistry going on in those cells like Bob and some of the links have said. I think you just need to pick a point and go with it because between not having true lab grade calibrated test equipment, taking multiple samples of the electrolyte from different depths of the cells and averaging them, I doubt you will ever get where you think they need to be. It just seems like you are over charging them. Consider most people don't do 1/4 of what you are doing to monitor them and the batteries will last a really long time. Call up the Trojan battery engineers or technicians at their headquarters and have a talk with them because they should be the true experts who have done all that testing and can give you the best advice.
Larry
Thanks Larry, This is probably true. I will probably just call Trojan and see what they say. And then settle into a good "rhythm" of cycling.
Quote from: Vic on January 15, 2018, 09:57:38 PM
When did you make the SG measurements that did show SGs at about 1.260 (how long AFTER the Classic had gone Float were those SGs taken)?
At about 3pm when the battery had been in absorb for over 3 hours. Had not gone into float yet.
Quote from: Vic on January 15, 2018, 09:57:38 PM
What was the charge stage at that time?
Absorb
Quote from: Vic on January 15, 2018, 09:57:38 PM
What caused the battery voltage to drop, the WB current to go negative in the center part of the Diversion area (heavy extra load) ??
Yes a heavy diversion load. I turned it off after I checked the SG and got the reading of 1.260 and increased the absorb voltage to try and get a finished charge. But as you can see from the graph, the amps had already dropped to about 3-4 before the load came on. And had started to level off at that point. As Larry was saying, this should indicate fully charged, But the SG was still saying 1.260 or 90%. That is why I am confused.
And in a previous post you wrote ...
Quote from: Vic on January 15, 2018, 09:57:38 PM
How about trying to cycle the battery bank more deeply, perhaps by Skipping Days on the Classic?
How is the Skipping Days done? is that in the local app at the setting "Days Between Bulk"? If I use Skipping will I still get solar energy to loads, just not any charging?
Mike
Vic .... I think I found where you explained it ... (at post #11)
http://forum.solar-electric.com/discussion/23052/quick-question-for-midnite-classic-owners
Matrix,
First, YES, Skip Days IS Days Between Bulk in the App, and Skip Days in the Charge>Advanced menu on the MNGP.
During a Skip Day, the Classic begins the day in Float MPPT, and will eventually get to Float, if there is enough input power (usually PV), and the loads on the system are not too great for the CC to get to the Float setpoint.
A battery that has experienced some discharge will still accept considerable charge when the charging voltage is held at a reasonable value of Float voltage.
The one thing that you should know about Skip Days, is, that on the day that the battery is going to get its full-charge, it the Absorb stage is not complete, due to too little PV power available to charge the battery and supply power to the loads, the Classic will NOT try to do a full-charge on the following day (it will just start the Day Skipping pattern again).
AND, YES, loads will still be supplied from your PVs, as long as there is enough PV power available to supply those loads, if there is too little PV available, the CC will revert to Float MPPT, just as it does with any other voltage-regulated stage.
In the Graph you attached earlier, that area in the center of the Diversion area where that extra load came on, the CC simply MJUST have reverted to Bulk, and NOT remaining in Absorb ... this area shows the battery being discharged.
And, IMO, the part of the battery charge current (WB current) "starts" to level off, does NOT represent the nominal EA value that should be used. If one uses the current at the beginning of where the charge starts to level off, the Absorb will generally NOT have been long enough.
If one chooses an EA value from where the WB current had definitely STOPPED decreasing for some period of time, this will be a better EA value to use. There is some Jitter in the WB current readout, and this does make it a bit more difficult to determine when the WB current is decreasing.
AND I would strongly suggest that you STOP using a Diversion Load on this system, until you get a better handle on what Vabs and EA setting will allow for your batteries to be fully-charged on a typical day from the Classic.
YES, previously, you said that your concerns were when charging from the SW, but it seems that you are also having the same trouble when charging from the Classic.
Earlier, I mentioned the effect of large Opportunity Loads on the EA function, and how voltage drops in the cable and breaker that connects the CC's output to the battery. A large opportunity load (large current) reduces the charge voltage that the battery "sees", and this voltage reduction at the battery terminals results in a lower charge current (WB current), and can trigger an early termination of Absorb. This CAN result in some undercharging of the battery.
This same effect could also result from using the SW to charge batts, Again you could measure the battery terminal voltage when charging from the SW to see what is effect on charge voltage from large opportunity loads.
IMO, FWIW, Vic
Thanks great info that makes good sense.
Always appreciate the feed back from the forum. It's nice to have some folks to bounce my thoughts and issues off.