Ending Amps not behaving as expected

[Vic]

Hi boB,

" -- Was CC at Absorb V and charge I below EA setting",  NO.

Bulk time lasted about 1:20,  Absorb time was about 1:20.

Min Abs time was 00:00,  Max time was 4:20.
EA was set to 14.5  A.  At the end of Abs,  charge I was about 27.7 A.   The last Logged Absorb power was about 1635 Watts.

EA appears to have been ignored,  but logged data seems to strongly say that  Bulk time had ended Absorb.  EA was FAR from being met.

The CC had finished its Abs with a time  of 1:20,  and was in Float upon my arrival at the site.  To get down to the correct Ending current for the bank,  an ADDITIONAL three hours of Absorption time was required.  So,  IMHO,  the CC did not use the EA value,  and it is strongly implied that it used Absorb time = Bulk time.

That is all.  We are still in A/C season here.  This adds unpredictability to the required charge time.

I have gone back to Min and Max Abs time for now,  BUT this may be what causes A=B time mode,  I really have never known just how A=B mode is triggere,.  but this is what i would love to avoid,  as it requires daily attendance and monitoring of just what did happen,  and often would require daily changes to Abs settings, and possibly manual Force Bulk etc.   This daily attendance just does not work right now.

This batt bank is seven years old,  and we have become friends.  I do not want to hurt my firend.  There is one lagging cell,  which needs to be replaced,  otherwise I would leave the CC off for a week at a time,  and just recharge manually every week ...   and so on.

I may need to snag an additional Classic for the residence here,   so I can watch its daily cycling.   The remoteness of the site with the Classics makes me want to not adopt  Beta FW,  at least until it has been rung out by others for a week or two -- for now, I am a late adopter.

Thanks boB & MN,   Vic

[boB]

Hi boB,

" -- Was CC at Absorb V and charge I below EA setting",  NO.

Bulk time lasted about 1:20,  Absorb time was about 1:20.

Min Abs time was 00:00,  Max time was 4:20.
EA was set to 14.5  A.  At the end of Abs,  charge I was about 27.7 A.   The last Logged Absorb power was about 1635 Watts.

AHA ! I think I see the problem !

If the battery output current was 27 amps at the end of absorb, then the EA setting of 14.5 amp is set too low by at least
13 amps.  The battery current must drop BELOW the EA (14.5) set point AND the battery voltage must be AT (or real close
to) the Absorb voltage...  Both conditions must be met in order for the EA to end the Absorb time early.

As for max and min time, I would just find out what the EA drops down and levels out to after your friend says
that its' absorb cycle is done then maybe add just a little bit more time to allow for extra loads.  THEN, if the
EA requirement can be met, your friend can go to Float and the job will be done for the day.

Personally, I think I would use the newer mode where you put in an absorb time (not minimum or maximum) using
the newest software with VMX (VariMax disabled) and then let the EA do its thing to end that time early if possible.

You will really want a battery monitor when we get ours going.  That's the real way to use EA but as long as
your DC loads are small enough where you know your EA can work OK, then you should be fine now.

boB

[boB]

OK, Ryan set me straight on what you were asking...

If you do not want the Absorb time to just go only as long as the Bulk time did,
set the MINIMUM absorb time to the shortest amount of time you want it go
go for.

The Absorb counter STARTS at your minimum absorb time and counts UP until it
reaches the Absorb voltage and then starts counting down to zero (0) time and
that is why it is absorbing for as long as it is bulking...  But usually the bulk
time will be longer because there is less power available earlier in the day and
it will just count up for quite a while the way the old software worked.

boB

[Vic]

Hi bob,  (Ryan),

Well for the systems here EA on the CC is fine,  and really the ONLY way to reliably recharge these banks.  Both of these systems have used MX-60s since inception.  The most remote system has had the MX replaced by two Classics  a number of months ago.

The EA function on the MX worked very well.  EA on system 1  is set to 16 Amps EA,  as there are,   on average somewhat more loads on this system.   This is the setting that fully recharges the battery every day.  The SGs are just where they need to be.

The remote site with two Classics also needs to use CC EA as the terminator of Absorb.  Its ideal setting is 14.5 Amps.  With generally light,  but variable loads,  EA is really essential,  unless one wants to change the Abs time every day or two,  and I cannot do that.

On the MX-60,  the ABSOLUTE way to use EA,  to the exclusion of all else,  other than Max Abs time,  was to Set Min time to 00:00,  Max time longer than one believes the bank would ever need,  and then the MX would always use CC EA to end Abs.  This is the way that the banks were always recharged when using the MX CC.  Due to widly varying loads CC EA  does work quite well.

I will admit that it can require load shedding as manually monitored actual battery charge current begins to approach the correct value,  and so on.

YES,  a real Bat Mon mated with the Classic CC would be better.

I had thought that I had seen EA  work,  but it may have just been a coincidence that it happened to be about the correct CC charge current,  when the time combo timed-out ...

I HAVE guessed the correct time parameters of this system to get the bank fully charged on a few days in the past.   BUT,  I DO need a CC EA function.  It can be from an MX,  until things settle out.   It is really the only way that these banks really get fully charged,  with very little overcharge.  And if over/undercharge is noted,  then EA gets tweaked a bit,  as SGs get monitored frequently.


OK,  BUT,  as I read it,  there may not be any way for EA to be the Abs termination with the 6-29-12 FW (?). As I read your post boB,  seems that there will always be the interaction on  Min time and what Bulk time happened to be on a given day,  even if Min was 00:00,  and there was a reasonable EA value set??  If that is the case,  EA would seem to be a don't care.

SRI to be ssooooo tedious.   Thanks,   Vic

[boB]

I believe that the problem in your scenario is that you have minimum absorb time set too low.

Set minimum and maximum to a high amount of time and let the EA do the ending of absorb.
Try it on your home system and see if that doesn't work.   It may be that 6-29-2012 did not
work correctly ??  Now I better go look...

OK, looking...

Looks like 6-29-2012 code should be good for EA.

You can verify that EA is working by setting the EA to something above whatever amps your Classic
is putting out in Absorb (with more time to go on the counter) and see if it goes to Float after
one (1) minute.  I would set it around 1/2 amp above just to make sure the Classic doesn't see
some amp-jitter.

boB

[Vic]

OK  Thanks boB,

The home system is charged by the MX-60,  so I cannot try this just now.

Certainly,  the MX seems to require Min time = 00:00.   It has been my feeling that is the 00:00 setting for Min that tells the MX to use EA.
Of course,  the MX has nothing to do with the Classic's EA function.

Will try it within a few days.  Some of my misunderstanding is that in the case that you describe,   then,  Min Time is not Min Time,  but is NOT ignored by the Classic,  I guess.

I do hope that EA will be dominant,  where Absorb is terminated ONLY by EA,  or Max Abs Time,  and ignore Min time,  and have nothing whatsoever to do with Bulk time for the present charge cycle.

Thnak you very much,   Vic

[Vic]

I believe that the problem in your scenario is that you have minimum absorb time set too low.

Set minimum and maximum to a high amount of time and let the EA do the ending of absorb.
boB

OK,  Thanks boB.  Was at the site a few days ago.  Tried your suggestion,  and the approach of increasing Abs time higher than the EXPECTED time required to reach the EA value SEEMED to allow EA to  WORK OK.

But,  just to try to be clear;

It would be very advantageous to me,  to have a way to set EA which completely IGNORES ANY Abs TIME SETTING,  or a way to set EA that ONLY LOOKS AT Max Abs time.

To me, having to guess how much time JUST MIGHT BE REQUIRED to reach EA  seems to have little or nothing to do with the Ending Current into the bank.  From years of experience with the friendly banks here,  EA is THE best way to end Abs.  If that EA value is never reached,  then the bank did not reach full charge,   and the amount of time it took for the bank to not become fully recharged is of no consequence (to me).  And the need to guess a time that will always exceed time required time is something that seems to me to just get in the way.  EA in my situation of variable,  but light loads much of the time dictates that EA is the best approach,  to the exclusion of ALL else.  Absorption time,  for me,  ideally should have nothing to do with the function of EA.   Having EA OR Max Abs time setting terminate Abs is OK,  but Max time is  not necessary (IMHO)  ...  but I'll take  EA OR Max Abs time (setting).

While I am not a control freak,  I would love to feel that I  have control over the  way EA behaves,  and it appears that there is a time variable (Min Time)  that has the unpredictable variable of the amount of time spent in Bulk.

The fact that a Min time setting will always have Bulk time added to it also makes testing less predictable,  because when the CC is in Float,  and one wants to SEE how the CC behaves during the transition from Abs to Float by Forcing Bulk,   the Bulk time of often a minute or two,  and this is bound to change the Min time from the way it was when the inital charge cycle of that day.   This seems to make it impossible for one do duplicate just WHAT FUNCTION actually did terminate Abs on the initial charge for the day.

Done belaboring the point for now.  Thanks!  Vic

[boB]

It would be very advantageous to me,  to have a way to set EA which completely IGNORES ANY Abs TIME SETTING,  or a way to set EA that ONLY LOOKS AT Max Abs time.

You can make EA be the only thing that makes it go to Float by setting the Absorb time to the highest it will go which
I think is around 18 hours.  Then, EA will be the only thing that makes it go to Float.

EA does ignore absorb time.  EA does not "look" at any timers at all.  If EA is satisfied, (60 or 90 seconds), it forces
a Float from absorb.  Time has nothing to do with that unless absorb time is set too short.  I thought you wanted
absorb time to force a float in case EA wasn't going to work.

So, I would say that you want to set the minimum and maximum absorb time REAL long...   If you have the latest
software, don't even use the minimum absorb time....   Just absorb time which is what is available if VMX is not
enabled.  If the older software before VariMax, just set minimum and maximum to a very long long time like
17 or 18 hours and then EA will be what forces it to go to Float.

boB

[SolarMusher]

Hey Vic,
Don't worry with Min and Max Time, on mine mini is set to 30mn and max to 4hr. EA value always stop absorb.
I've added 1.1kw to my 2.1kw array two days ago, and I've noticed that my end current is now 2A higher than it was with my 830AH/48V bank this summer (7.6A). I don't understand exactly why, maybe someone has an idea.
For now my EA is 9.6A + loads and it works fine with the 6-29-12 FW.
Try to set it to 30mn Min and 6hr Max or more, it should work. Time has nothing to do with EA.
Good luck,
Erik

[Vic]

Hi boB,  Erik,

OK  boB,  will increase the Min and Max times during the next site visit  and see how we do.

Air Conditioning season ended last week,  so that part of variable loads is done for this year,  which will help things.

Eirk,  often,  as short Bulk and Absorb does the trick,  but at times,  with greater DOD,  Absorb = Bulk time will yield a too short Abs,  as will Min Abs time + Bulk time,  but will increase min and max times,  and monitor results.

Thanks for the info.  Vic

[SolarMusher]

Hi Vic,
From what I understand, your problem could only come from a very little DOD every day. It can't come from Max time because EA would stop your Absorb before max time is reached if set to 6hr or more.
In your case, Min time could be a problem if your bateries are near full every day. I don't think 0 mn is a good min time value for you maybe 30mn/1hr could work better. But if you want to be sure EA will be the only way to control the absorb, why don't you set your time to Min time/5hr58 and Max time 6hr  ? This way, you'd be sure only EA could stop your Absorb.
Try it, you have nothing to loose. Hope this help.
Good luck,
Erik

[Vic]

Hi Erik,

Sorry,  had thought that I'd replied to this ...

The ONLY reason that had been using 00:00 Min Time,  is that this is what was required on the MX-60 for it to use EA OR Max time.  Had guessed that this would also be the case for the Classic,  given the genes in each of these CCs.  And,  guess that am hung up on how important TIME is, vs Current.  When EA works,  the time is not relevant to me -- Min or Max,  but I will take Max time if forced to,  and Min almost = to Max should be fine,  guess ...

Thanks,   Vic

[boB]

Hi Erik,

Sorry,  had thought that I'd replied to this ...

The ONLY reason that had been using 00:00 Min Time,  is that this is what was required on the MX-60 for it to use EA OR Max time.  Had guessed that this would also be the case for the Classic,  given the genes in each of these CCs.  And,  guess that am hung up on how important TIME is, vs Current.  When EA works,  the time is not relevant to me -- Min or Max,  but I will take Max time if forced to,  and Min almost = to Max should be fine,  guess ...

Thanks,   Vic

Ahhhh....   Consternation, turned to lucidation !

Excellent, Vic.
Glad you got it now.

boB

[Vic]

Hi boB,

Yea thought I got it some time ago,  but today did see something curious ...

Went to the remote site with Classic CCs today.

Was surprised to find the single Classic that does all the charging in Float at about 10:30 AM.  Mostly cloudy day.

Looking at the Log,  see Bulk Power levels slowly ramping up then remaining around 585 Watts --  about 11-12 A on this 48 V system.    Noted that at 10:11 AM,  CC was delivering 583 Watts,  then at 10:21,  the CC was in Float,  delivering 87 W.   No recorded Absorption stage ... 

There were 1.6 Kwh delivered today at time of arrival,  rough normal amount is about 2.1 Kwh,  although this does vary,  primarily due to run time of a small 120 VAC referigerator.

Running the 6/29/12 FW for both the Classic and MNGP.
Min TIme 2:44,  Max Time 4:20,  EA 16.1A.

Looking at the SGs,  the bank was mostly charged,  so looks like the Bulk was good,  just needed an Absorption.

Have there been any changes to the way Max, and Min Times work,  or how EA functions between this older FW and the present Production FW?

Before leaving the site,  set EA to 00:00 or 00:01 -- whatever is the lowest,  and set Min Time to about 1:30,  Max 1:31  which are probably too long.  Will need to return tomorrow to try to guess a new time.

Guess that due to the high SOC at the start of today's charge (and on almost all other days as well),  that the slow lowish average current Bulk eventually got to Absorb,   and  Absorb current was below EA,  so  went to Float essentially instantly ... 

So,  what am I doing wrong?  Had expected that the Classic would do the Absorb,  because believe it  finished the Bulk,  would expect that EA would NOT be satisfied  in this situation,  as charge current never exceeded EA.

Thanks,   Vic

[boB]

Guess that due to the high SOC at the start of today's charge (and on almost all other days as well),  that the slow lowish average current Bulk eventually got to Absorb,   and  Absorb current was below EA,  so  went to Float essentially instantly ... 

So,  what am I doing wrong?  Had expected that the Classic would do the Absorb,  because believe it  finished the Bulk,  would expect that EA would NOT be satisfied  in this situation,  as charge current never exceeded EA.

Thanks,   Vic

The first (top) sentence I understand.  That makes sense.  When the voltage is at absorb and the current is LESS THAN the EQ setting,
then it will go to Float early.

The second sentence I don't understand...  " EA would NOT be satisfied  in this situation,  as charge current never exceeded EA"

When the voltage is at absorb and the current is LESS THAN the EQ setting, then it will go to Float early.

There has been a very slight change regarding the latest firmware or two regarding this and for good reason, mainly having
to do with when using multiple charging sources...
That is, the minimum EA setting now goes to zero (0.0) amps...  This is actually "DISABLED"....

Problem before was that IF another classic (or any charging source) is holding the battery at or above Absorb voltage,
then the OTHER Classic will NOT be outputting much or any current BUT it will be at Absorb voltage and that will
satisfy EA requirements !  That is a no-no because that Classic isn't doing ANY work, possibly.

So if that OTHER classic sees the voltage at Absorb and its current is reading 0.0 amps, that is less than 0.1 amps.

If you have two or more Classics networked with Follow-Me in the system, the OTHER Classic, with amps less than
EA setting and seeing the voltage at Absorb would go to Float and take the Classic to Float with it.

Thanks to Chris Olson for finding that one.

So, now, 0.0 amps is a special case which actually disables going to Float when those parameters are satisfied.

I am surprised that the MX60 did not show this problem, at least while I was working on it.

boB