Not getting Full SG using my Conext SW charger

Started by Matrix, January 13, 2018, 03:05:10 PM

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Matrix

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.
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Vic

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
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Matrix

#17
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. 
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

ClassicCrazy

#18
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
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Matrix

#19
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. 
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Vic

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
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

ClassicCrazy

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
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Matrix

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.
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

#23
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


Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Vic

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
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Matrix

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. 
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install