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SoC% false accuracy? State of Charge
#91
(09-05-2020, 03:16 PM)OffGridInTheCity Wrote: Can you tell me exactly what "Re-Calibrate at Low SoC" actually does?  I can't figure it out.  [,,,]

In fuel gauge terminology an SOC recalibration usually means that when you are at some known SOC you reset that gauge to this known value. In the simplest case the SOC is "known" by mapping a (near)resting voltage to SOC (based on known V to SOC tables).  This serves to eliminate any errors that have accumulated over time. 

Often the "known SOC values" used are those near empty or full, but they can be any value in the used range (= "virtual battery") that is attained frequently enough at (near) rest so that the SOC can be accurately calculated from the voltage (if they are not attained frequently enough then the errors can accumulate to large values).

So in your case when you reach the empty voltage of your virtual battery (49.5v = 3.54v/cell) you want to reset the fuel gauge to 0% in order to recalibrate the SOC of your virtual battery.

As for what is actually implemented in Batrium's simple coulomb counting fuel gauge I can't say, since it is very poorly documented, and I don't have one to reverse engineer it, and not enough has been said above to infer such. If I owned one I would contact tech support to attempt to obtain better documentation. You certainly deserve such given the high price point.

To learn much more about fuel gauge algorithms (including much more accurate algorithms) see the Barsukov book linked here.
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#92
(09-05-2020, 03:16 PM)OffGridInTheCity Wrote: YIKES - I just set "Re-Calibrate at Low SoC" to 30% and then forced the Metrics to 25% and it went to 0% immediately.   Unfortunately - this caused the shunt to stop reporting Shunt V, A and W!!!  they went to 0v, 0a, and 0w.   
Doesn't look like a good solution as I do care about Shunt V, A, and W a lot more than SoC  Sad
That's more like a bug & not supposed to happen!

Do you have gear (eg an oscilloscope) to look for HF noise at the shunt particularly when the inverter is running?

I just did the daily history export from Batrium (for ~2.5 years data) & got
Cumulative Charge Ahrs = 141044
Cumulative Discharge Ahrs = 139688
So about 99.03% efficiency reported (edit, corrected %)
Running off solar, DIY & electronics fan :-)
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#93
Thanks to you all - I think I've got the outlines of Batrium SoC operations.  Operating in the middle v range / off-grid style with varying max v(s) per cycle + an unusable Batrium feature / suspect shunt situation has rendered SoC 'not good' for me at this point.  

Fortunately I have perfectly good metrics with out Batrium SoC and my voltage curves (due to such a large battery / relative steady consumption) are quite steady - so operationally I'm good.    But I understand better now why many focus on SoC and I don't Smile


P.S.
>Do you have gear (eg an oscilloscope) to look for HF noise at the shunt particularly when the inverter is running?
Thanks for the suggestion but no scope.  
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