Classic is LiFePo4 charging, how correct wrong SOC?

[binkino]

Hi,

I changed to LFP and habe 2 Classics.
One "East" and one "South" Classic. The "South" has the WBJr.

The Classic's SOC doesn't reach 100% anymore since I changed to LFP (doen't matter, does it?) but the SOC is drifting away. While the SOC of the LFP has 84%, the Classic shows 99% and stops charging (generating energy)
The "East" hast no WBJr. and continues generating energy, as vailable and needed. But as the "South" thinks, the battery is charged, it doesnÃ,,t kick in to generate energy.

How can I correct the SOC in the Classic?

I tried now manually "force" the "Absorb" function, so it stared generating energy again.
(Status panel, Config, Basic)


If you have any idea how to fix this - have a workaround, I really appreciate it, thank you

[Steve_S]

I run 3 packs of 24V/280AH & 2 packs of 24V/175AH in one bank for a total of 1190AH of LFP.
All equipment MUST BE Voltage Corrected & Calibrated (VERY IMPORTANT) correcting for Line Loss is critical.
Divide Values X2 for 12V. Multiply X2 for 48V.

Here are my current settings:
Absorb: 27.5 for 30 minutes (3.4375vpc) (some call this boost) *15 Mins is fine, mine is bigger due to # of packs.
Equalize: OFF
Float 27.4V (3.425vpc)
MIn Volts: 21.2 (2.650vpc)
Max Volts: 28.7 (3.562vpc)
Rebulk Voltage: 24.5 (3.062vpc)
End Amps: 14A (*1)
(*1): End Amps is calculated from the Highest AH Battery Pack in a Bank. IE: 200AH X 0.05 = 10A 280AH X 0.05 = 14A.
NB: Victron Forum discussion says EndAmps = TailCurrent

Coulumbic Efficiency / Battery Status Meter Efficiency for LFP = 99%.
This get's the bank charged to full with high amps (Constant Current) and then float (Constant Voltage) tops off so the cells are on average between 3.400-3.420. I am running 7/24/365 so float is used up by the Inverter + provides whatever the packs will take to top off.
* Do Not forget to adjust for Voltage Offsets between Actual Voltage @ Battery Terminal & at Solar Controller.

LFP Full Voltage Range is from 2.500-3.650. 
LFP "Working Voltage Range" is from 3.000-3.400
From 2.500-3.000 _and_ 3.400-3.650 are the steep curves which only represents roughly 5-7% of "Gross Capacity" which is outside of the AmpHour rating.  An A+ LFP Battery using 100AH cells, the "gross  capacity for 2.50-3.650 will be between 105-107AH but the 100AH is within the 3.0-3.4 Working Range.

See Attachments from a guide I prepared a while back.
Hope it Helps, Good Luck.

[boB]

Hi Bink..

So, as Steve_S says he is using amp-hour efficiency of 99%,  I am curious what you are using for that efficiency ?

boB

[Steve_S]

I am ALSO Using the WizBangJr to determine the EndAmps, not using it leas to various peculiarities.  Tried it just to see and wasn't long to realize that's not a great idea.

[binkino]

Thanks



I had it set efficiency to 99% but later set to 95%, that looked to be a good value
After the post above I set it now to 99% again


I need the correct SOC in the classic to switch the relay that disconnects the Westech inverter (I really need a better one asap) from grid above 30%SOC and connects the inverter back to grid below 30%SOC.
Actually the SOC of the LFP is below 30% and the Classic shows 47%

I have now manually activated the AUX1 for the relay that sits in line to the inverter, so nothing goes wrong tonight.



Is there a way to write the value direct to the register in the Classic?
I can read the values from the LFP and the Classics for my pages.
Some years ago Wade wrote for me a page where I can edit the AUX settings. Is it possible to send (and overwrite) the value of the LFP SOC to an address in the Classic? (just ideas ... thoughts...) So I could sync them?

[boB]

"Is there a way to write the value direct to the register in the Classic?"

You mean, write or set the SOC%  in the Classic ?  I don't think so.   Had not thought of that before.

Thinking....     Maybe you could change the SOC%  by changing the capacity ?  I can't remember if that would work or not ?

Or, maybe change the temperature coefficient per degree C ?

Might be worth a shot.

[binkino]

🤔 really looks like the efficience was the caus. But took long to drift that much.
Today The battery was charged wihout the load of the inverter, and Classic shows 99% and LFP shows 100% again

[Steve_S]

Classic shows 99% and LFP shows 100% again

That is not unusual, when you look at the "Net Ah:" if it is at 0 or -# that will happen,  IF the number is positive then you will see 100% (usually when in Float).

I look at my WizBang Data via the Software or the Classic screen itself, if it says 75% I look at the BMS Application and it is the same.  The same applies when at 100% Full.

A Side Note:  Not all BMS' (Battery Management Systems) have Applications to monitor them, some have displays, and "Dumb BMS' " are without any user interfaces so you never really know what is going on internally.   NOT All Smart-BMS' have really accurate  Coulomb Counters and the tech varies on the level of the component.  Batteries from BattleBorn, Relion, SimpliPhi which are large commercial producers (just to name a few) all use Intelligent BMS and several have software interfaces.

I Build my Own System Packs as well as for others occasionally, I am now using JK-BMS' with Bluetooth (incl. App), RS232/485/Canbus protocols for external interfacing.  These also have Smart Active Balancing which works exceedingly well.  The Coulomb Counter & Internal Shunts are Quite Accurate.  They are good enough that I just replaced $3000 USD worth of BMS' within my own Battery Bank System and my Utility Packs as well.