A puzzle: More kWhrs showing than could possibly...

[openplanet]

Two Classics, two arrays, each array putting out about 1.2 kW in full summer sun. 20kWhrs of LifePO4. 
Day 1: float reached by late morning and no specially heavy loads used for the rest of the day. 
Day 2: float reached by late morning, and each Classic shows 3 kWhrs harvested, for a total of 6 kWhrs harvested.  Again, no specially heavy loads used.

That's over 25% of total battery capacity. 
It seems virtually impossible, based on my experience through rainy spells and winters, that the remainder of Day 1, after float reached, could possibly have involved the consumption of 6 kWhrs to recharge the batteries and run the (very light) loads.

Any thoughts about this?  As an aside, I've always wondered why the WbJr menu item doesn't show total kWhrs harvested per day across all Classics.  Wouldn't this be an obvious, and highly useful value to show, rather than having to add the kWhrs harvested by possibly many Classics?

Thanks in advance, as always.

[boB]

As an aside, I've always wondered why the WbJr menu item doesn't show total kWhrs harvested per day across all Classics.  Wouldn't this be an obvious, and highly useful value to show, rather than having to add the kWhrs harvested by possibly many Classics?

Thanks in advance, as always.

The WB Jr. does not know from where that total kW-Hours of charging came from.   It could have been from Classics and also other charging sources.

Will have to think about the first questions,  however,  energy also racks up from being in Float for a while as well as Bulk.

What is the amp-hour efficiency set at ?   

Also, what is your nominal battery voltage ?   12V ?   24V ?   48V ?

[Steve_S]

LFP Efficiency is 99% and the WizBang has to be set for that, with the AH Capacity of your bank and 0% Compensation.
I'm running 1190AH/30.4kWh of LFP in one bank, with a Classic-200, 2kw of Panel facing Due South (ground mounted at 45 degrees).  I am usually in float mode by Noon and am 100% Offgrid, rural & remote (no grid power).  Because there is constant load being handled that knocks down the charge amps a bit.

One thing some folks get a tad confused with is while the SCC may be in Float, if there are enough incoming amps, that will be used by the inverter before touching the battery packs.  So if you turn on a 50A device (nuker / coffee maker for example) and if there is enough Solar Amps it will use that first.  BUT if solar can only provide 30A the balance will be pulled from the battery and as soon as the load is gone the SCC flips back into MPPT Bulk and starts it all over again to float and then topping off.   This will also show up in your kWh production numbers making it look sort of odd unless you know what is going on.

One thing many do, is to put a SmartShunt (like a Victron one) in front of the Battery DC Bus so they can monitor strictly was goes in/out of the bank and with the Wifi/Bluetooth app it's a quick way to see it all at that point.

Depending on the type of BMS used, some can show you what each battery pack is doing as well.

Here is my Classic-200 Profile, which never triggers an HVD and allows the cells within the packs to level up to within 10mv or less very nicely.   I am 24V using 280AH & 175AH Packs in a bank.

LFP working Voltage Range is 3.000-3.400
LFP Minimum Functional Voltage is 2.500 and Maximum Voltage allowable is 3.650 per cell.  Below 2.90 & above 3.500 only represents rough 5% overall capacity which is typically reserved out.

All equipment MUST BE Voltage Corrected & Calibrated (VERY IMPORTANT)
we are talking Millivolt sensitivity and not forgiving like Lead.   

Divide Values X2 for 12V. Multiply X2 for 48V.
Absorb: 28.2 for 15 minutes (3.525vpc) (some call this boost)
Equalize: OFF
Float 27.9V (3.4875vpc)
MIn Volts: 22.0 (2.750vpc)
Max Volts: 28.7 (3.5875vpc)
Rebulk Voltage: 27.7 (3.4625vpc)
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
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 3.475-3.500. I am running 7/24/365 so float is used up by the Inverter + provides whatever the packs will take to top off.

** Coulumbic Efficiency for LFP is 99%

I suggest you may want to look at the attached PDF - particularly pages 12-13 for the LFP Voltage Charts.

Hope it Helps, Good Luck.
Steve.
PS extra info provided for readers who follow along later.

[openplanet]

Thanks to you both.

boB: Even though the WbJr. can't differentiate between charging sources, wouldn't it make sense to add that parameter, so one can see daily kWhrs into the battery bank?  Ahr efficiency set to 98?  Battery bank nominal 48v.

Steve: Thanks for the extensive reply.  My parameters are set very close to yours (correcting for 24 vs 48 volt systems).  I have verified that, when in float, my Classics divert available array power to loads, as they're supposed to.  I'll study the attachment. 
Question: You state "One thing many do, is to put a SmartShunt (like a Victron one) in front of the Battery DC Bus so they can monitor strictly was goes in/out of the bank."  This is exactly what the WbJr. does, isn't it???

Bottom line, still somewhat of a puzzle!

Again, thanks.

[Vic]

   ...   Question: You state "One thing many do, is to put a SmartShunt (like a Victron one) in front of the Battery DC Bus so they can monitor strictly was goes in/out of the bank."  This is exactly what the WbJr. does, isn't it???   ...
Again, thanks.

YES,  exactly !,   (although, guess that it might depend upon the meaning of "in front of").

Vic

[boB]

Thanks to you both.

boB: Even though the WbJr. can't differentiate between charging sources, wouldn't it make sense to add that parameter, so one can see daily kWhrs into the battery bank?  Ahr efficiency set to 98?  Battery bank nominal 48v.

Oh, do you mean kW-Hours instead of Amp-Hours ?

That could be done of course.

boB

[Steve_S]

A Victron Smart Shunt is very similar to a Wizbang but with BlueTooth and an app with a few other minor differences. 

"In Front of" depends on the config of your system.   
Each of my BMS' has a physical shunt and all attached to a common DC Bus. Allows monitoring each pack as to what goes in/out.
The DC goes to my EPanel with the Wizbang, there SCC & Inverter/Charger input/output is seen to the entire battery bank.

Yesterday it only took 4.1kwh to charge my bank & run my house at the same time and into float by noon.  Nice sunny day.
Today 5.7 kwh cloudy morning just "touched Float" by end of day.  In December it's a whole other story, thank goodness for lots of reserve.  It's just another of another cloudy, hazy (possibly smokey) day in the life of a Solar System that skews the numbers.

[openplanet]

boB--Glad to hear it'd be a cinch to add kWhrs to WbJr menu.  Can we expect it in the next firmware update?  And can we expect next firmware update this coming Friday?   

[boB]

boB--Glad to hear it'd be a cinch to add kWhrs to WbJr menu.  Can we expect it in the next firmware update?  And can we expect next firmware update this coming Friday?   

Unfortunately not this Friday !

I need a clone of my own and then we could do twice as much