MPPT Tracking in Legacy P&O

[Vic]

Have mentioned this several times,  in the past  --  at least in Legacy P&O Mode (L P&O),  when going from the Float stage,  just after Absorb just finished,  to Manual EQ,  the Classic will not Sweep,  ever.

FW 2186.

Set manual EQ,  Classic was in Float,  but delivering little power,  due to the Surface Charge of the FLA batts.   Went to do a chore,  returned twenty minutes later to check EQ progress.   CC was delivering 315 Watts,  stage was EQ MPPT.   EQ V set to 62.8-ish temp comped.  Vin was 115.4,  Voc about 117.8V,  battery volts = 51.4-ish.

Air Con was running,  and the battery was discharging at about a 15 A DC rate.   Pressed Enter,  nothing happened,  pressed it again,  again,  again  ....   and again,  and no new Sweep.

So pressed the Left Soft button about thirty times,  and that got the Vin,  to about 85 V,  and the CC was making about 3800 Watts.

This seems to always occur for the above set of parameters,  and actions.

IMO,  it seems that in L P&O Mode,  that the CC does not (possibly EVER),  make a new sweep,  after entering Float on its own,  at least,  when a Manual EQ has been initiated.

Have also seen this happen when switching from Solar Mode,  to L P&O when EQ has been initiated :

http://midniteftp.com/forum/index.php?topic=4211.msg41338#msg41338

I am saying this to,  perhaps,  help others,   AND,  also if the MPPT Tracking routine is being ported to the new lines of MN CCs  --  also,  it is quite possible the neither the Hawkes Bay,  nor the Barcelona,   have the L P&O function   ...   but,  just in case   ...

We often use L P&O,  when there is smoke from wildfires,  or some cloudiness.

FYI,   Thanks,   Vic

[boB]

Thank you Vic !  Sorry you have had to mention this yet again.

We are looking at taking care of a few bugs and/or annoyances in the Classic and MNGP.

This bit of information will help a lot !

boB...   In rainy Ocean Shores and Washington state.  Even Phoenix, AZ has a bad solar day today with rain that is needed.

[Vic]

Hi boB,

Thank you very much for the reply,  appreciate all that you do.

73,  keep dry,  very little chance of any rain here in the next ten days.    Have fun  TU again,   Vic

[australsolarier]

legacy mode, 12V system, parallel with victron 100/50
the midnite classic often doesn't start to work after switching over to float. it is just resting forever. just stays in resting mode. even though the V bat goes down to 13.2V.  the only way to get it to work is to force absorb for a while and then force float again.

[boB]

legacy mode, 12V system, parallel with victron 100/50
the midnite classic often doesn't start to work after switching over to float. it is just resting forever. just stays in resting mode. even though the V bat goes down to 13.2V.  the only way to get it to work is to force absorb for a while and then force float again.

Have you looked at the battery temperature compensated target voltage in the VIEW sub-menu under charging ?    The battery voltage that the Classic sees has to fall below that target before it will try.   

I would be surprised if it did not work but would like to know why, if it is doing this, AS
.

[australsolarier]

that voltage you are talking about seems to be 14V. that is the V absorb.
i am the bloke with the lifepo4 batteries and no temp compensation needed. the midnite seems to drop into resting mode, 38 if i remember. i think the problem has to do with the stiff voltages of the lifepo4.  it doesn't do it in the 48V system. it has 4 midnites though, so not so visible if one does it, however i have never noticed it there.
i have tried solar mode, it does not do that symptom there. however it tends to half its output after an hour or so. which can be reset by turning off and on, but then does it again. the power room is airconditioned.
as i see it it might have something to do with the small voltage range , 14V absorb, 13.2V float.

[boB]

Yeah...   The Classic should just go to Float when Vbatt drops below that setpoint or target.

Not sure what is up.   So, what is 38 ?   Is that RFR ?  Reason for Resting number ?

[australsolarier]

yes, resting 38 shows, if i remember correctly

[Wizbandit]

RFR 38 means another charging source is pushing the battery voltage above the Classic FLOAT setting so I assume the classic is in FLOAT, this is normal.  The Classic will not make/help charging unless the battery voltage falls below the float setting. Two high power charge modes are in the Classic, FLOAT MPPT and BULK.  FLOAT MPPT won't kick in if VBATT is sitting > FLOAT setting.

If you want the classic to help and the other charger is the one pushing the battery volatge up then you need to use the Classic setting "REBULK" to make it go back into BULK and help.

The downside to this is it starts another ABSORB Time unless you setup and use correct ENDAMPS to terminate it when the battery gets full.

[boB]

Here is my list of RFR numbers...





    ReasonForResting = 1    Wake state, (Vpv < PreVoc AntiClickSenstvty  (MB 4236)
    ReasonForResting = 2    Insane Ibatt on WakeUp state RFR
    ReasonForResting = 3    Negative current on WakeUp state
    ReasonForResting = 4    dispavgVpv < (dispavgVbatt - 10) Now -25 (RestartTimerms = 1500)
    ReasonForResting = 5    Too low power and Vbatt below set point for 90 seconds
    ReasonForResting = 6    FETtemperature >= 98.4 (always at start ?, Main) Hot
    ReasonForResting = 7    Ground Fault
    ReasonForResting = 8    Arc Fault
    ReasonForResting = 9    (IbattDisplaySi < -15) (negative current) (MB 4200)
    ReasonForResting = 10   (dispavgVbatt < LBDlowV)  Battery less than 8 Volts
    ReasonForResting = 11   Vpv >= 90% of Voc but NOT fast enough. Low Light #1
    ReasonForResting = 12   Vpv < 90% of Voc and taking too long.  Low Light #2
    ReasonForResting = 13   Vpv > (Voc + 10V) in    PV_Uset || Solar1_OandP
    ReasonForResting = 14   Vpv >= 90% of Voc but NOT fast enough. Low Light #3
    ReasonForResting = 15   Vpv < 90% of Voc and taking too long.  Low Light #4
    ReasonForResting = 16   Normally because user turned MODE OFF...  Disabled
    ReasonForResting = 17   Vpv > HyperVocV150
    ReasonForResting = 18   Vpv > HyperVocV200
    ReasonForResting = 19   Vpv > HyperVocV250

    ReasonForResting = 22   Average Battery Voltage is too high above set point  (RestartTimerms = 2000)

    ReasonForResting = 25   Battery breaker tripped  (Vbatt shot up high)
                            (If RFR = 25 on Wakeup, check modbus register 4200)

    ReasonForResting = 26   Mode changed while running, Vabsorb raised more than
                             10.0 Volts or Nominal Vbatt changed by modbus command
                             AND MpptMode was ON when changed... Otherwise, OK.

    ReasonForResting = 27   bridge center == 1023  (R132 might have been stuffed)
    ReasonForResting = 28   NOT Resting but RELAY is not engaged for some reason
    ReasonForResting = 29   ON/OFF stays off because WIND GRAPH is insane
    ReasonForResting = 30   PkAmpsOverLimit (will change somewhat 1-23-2013)
    ReasonForResting = 31   AD1CH.IbattMinus > 900

    ReasonForResting = 32   Aux 2 Logic input is high.  Aux2Function 15  (Conflict with OCP in Solar and Uset 1-9-2013)
    ReasonForResting = 33   OCP in a mode other than Solar or PV-Uset (1-10-2013)
    ReasonForResting = 34   AD1CH.IbattMinus > 900 Classic 150,200 newer than 1-23-2013
    ReasonForResting = 35   if(dispavgVbatt <= LBDlowV + 5) // state 0 11-27-2013 (Vbatt < 8.6 V)
    ReasonForResting = 36   Battery temperature is Greater than reg address 4261
    ReasonForResting = 136  Battery temperature fell below MB reg. 4161 - 10 C
    ReasonForResting = 37   12-10-2014  SanityPwrChkDis  LOW POWER CHECK <50W
    ReasonForResting = 38   8-4-2015  External charger.  zero watts @ set point 90 sec

    ReasonForResting greater than 100...  100 + PowerOnReset, WDT, etc...
    ReasonForResting = 104  Watchdog WDT reset (only at boot until first RFR)
    ReasonForResting = 111  Normal Power up boot (only at boot until first RFR)

                       100 +   1 = POR,  2 = Ext. Reset  4 = WDT  8 = Brown Out


POR, WDT,  External Reset (from the reset pin), Power On Reset,  Watch Dog Timer,

[australsolarier]

wizbandit,
yes, i agree with you are saying.
the V float setting is 13.4V. however, like described above, sometimes the midnite just doesn't wake up even though the midnite reading of V float goes down to 13.2V. and i turn off the external source.
so, it seems to me that "reason for resting 38" seems to have a timer built in that sometimes does not end. (like maybe that timer is too short?)
usually when after the float change the midnite kicks in quite early, so to say parallel with the victron.
it seems to me it also has something to do with the stiff voltage of lifepo4 batteries.
as for rebulk, ah yes, i described that above, i "force bulk" , wait till it settles in, then "force float" and then it also works. (if you rebulk you might get the same problem again)

anyway it is a minor issue

[australsolarier]

investigating closer,
the midnite swtiches to float. the batteries are discharging. but too slow for the classic. after a minute or so he switches to "resting (38: unknown)
the battery voltage showing on the classic shows 13.3V (float it is supposed to be 13.4V. 
the battery now slowly discharges. the voltage on the midnite goes down to 13.2V after about a 40 amp discharge.
now then, he switches to float,
but now the classic is pissed off because the victron is all the time working. even though in float he only contributes 1 or 2 watts.
ok, we wait to see what happens.
after so 50amps discharge of battery he ramps up somewhat, but the voltage is down to 13.1V (on the classic read out)
the battery is less discharging, though but never the less keeps on discharging.
force bulk,  the midnite by now is really angry. slow work protest. only 50-% of capacity
i had to do a bully reboot to get him out of the lethargic state.

as far as i concerned that "resting" timer should be prolonged to 10 minutes or so. i don't quite understand why the timer to resting is only 60 seconds or so. obviously the night takes hours to switch to bulk in the morning

[boB]

AS, sounds like it is just too close to Float voltage ?

The Classic, in any particular mode like Absorb or Float will let the voltage fall slightly below the actual set point (couple tenths) before it will return to the MPPT mode for that voltage.  Maybe what you are seeing is related to that ?   Haven't thought about this but for a minute so maybe something else.

RFR #38  means there is another charging source.  In your case, it went to Float after being up at Absorb voltage and the battery had to bleed off a bit.

I'm not sure what you mean by staying off for 10 minutes rather than 60 seconds ?

At least you had a 2nd charging source so not really a need for anything to bring the voltage up ? 

What we did at OutBack was to let the battery voltage fall below Float until a Re-Float voltage was reached and then it would come back to life and Float for a while.  That was to reduce unnecessary wear on the batteries.   I know you are not wanting this to happen here.  Just thought I'd give you a positive point for that

Now, I am not sure what happened when you rebooted the Classic ?   It should have come back up with a brand new bulk/absorb charge.

Did you force a new Float ?  Was there lots of sun ?

Not battery temp compensation modifying the set point ?   I seem to remember in a previous posting that this was not the case but just checking.

[australsolarier]

well about that timer :  when it switches from absorb to float:    the charge status says float, the classic does not produce, after ca 60 seconds it drops into that resting 38 status. so there must be a timer in there that decides : aha nothing happening i go to sleep. (that is the timer i am talking about.)
the day i described above was totally sunny. the load was about 1.5kw. the victron produces max so about 710w.  so, capacity, should bleed of to the 13.4 float set point. the victron recognizes that and slowly starts to ramp up. now as you can see we are using 1500w and producing 700w,  at some time you would think the classic will kick in again and not keep on sleeping. i mean, the classic does NOT know there is another dc source, unless that dc source is larger than consumption.
in the winter the panels of the victron are much reduced as they are horizontal for cloudy weather gain. then, it seems the classic kicks in before that 38 timer kicks in and stops everything. input is then pretty much balanced half and half between the victron and classic. except when the victron maxes out.  so at the moment victron has 268 and classic 276w.
to get the classic to work again, i have to force bulk, wait till the sweeps stop, then force float. then the classic usually behaves.
i should here also mention i have lifepo4 batteries, 800ah. and the solar controllers are totally over powered.
no temp compensation.

and ah yes, it comes back to the difference of lead acid and lifepo4 batteries. there does not seem to be that problem with the 48V setup. (4 classics and a large victron) the voltages of the lifepo4's are quite stiff. there is a big difference in 13.3 and 13.1 V  somewhere near 80%.
i might set the float V of the victron lower to see how that works.
anyway, thanks for listening, urs

[australsolarier]

bob,
i have now proof that that there is a timer to switch from "float" to "resting 38:Unknown"  status after switching from absorb to float.
i reduced the the float V of the victron by 5mV. so the victron kicked in a bit later. that 38 status appeared before the victron started to feed current. (slowly ramping the current up)

so i remain convinced  it is that timer switching from float to 38 that creates the problem.

so now the classid sits there sulking and protesting that it does not want to work with a lithium battery. because, i want to work with lead acid. i hate lifepo4. i protest.

ohhh, as a matter of fact, as i am writing this, the classic decided to spite me and kicked into float.  the ratio is of currents are 1 to 2 now with the classic doing the bigger part.
yes maybe the problem is the classic just doesn't want to work 50/50 with the victron impostor.
i keep you posted