Inverter - App - Battery % Indication

Hi,

So okay there are some weird and crazy settings that needs to be made in order for the inverter app (SmartEss as example) to display the battery % correctly, or near correct.

I have researched plenty and thanks to people like @Coulomb and the like, some information just added to the understanding of how these things calculate the %s.

In short, you have a new battery and slap it onto your inverter and set the settings so that your precious investments are operating within margins, such as:

16s 48V battery - Bulk/Absorb - 56.8V, Float 54V, Cut off 48V, etc etc. And here starts the fun.

The moment Uti power drops the inverter shows you 50% battery or something crazy. Well these things are actually doing stupid math on the settings you provided.

The % it will show is derived from Float Voltage - (Cut off Voltage + 0.2V) x 10% = ???

I have been thinking of this a while and it really is still not entirely correct in what it displays to you.

So let us delve deeper into the matter. There are also so many references to precise voltages and which % they represent but the average consensus are or there about:

When you set your float voltage on 54V soc you are actually already setting it on (according to above) 99.9% ish.

I personally set my float on 53.6, which according to above would be 99%, other tables indicate 53.6% to be (as below) - 90%

So for just to get to a point lets call it 90% SOC and be done with it.

Now, when the Uti drops I actually WANT to have two things (You need to decide what you want to see), shown, 1. 100% or 2.the % as per these tables.

I prefer to see the REAL percentage, which means 90%.

What happens within the first couple minutes under load is your Voltage WILL drop, by some margin, mine falls from 53.6 to a stable 52.8/7.

52.7 is under soc in the region of 70% capacity remaining. And this is the value I want to see, but I see according to the math:

52.7 - (43.4 + 0.2) x 10% = 93% (Complete hogwash)

What I need to do for my system to show me 70% is play with the cut off voltage.

52.7 - (45.5V +0.2) x 10% = 70%

So it really all boils down to what you want to see, this off course if you arent viewing through connection to the BMS and only relying on these Inverter Wifi Apps.

I am still going to see if there isnt a setting that would be closer to displaying the %, but with the very flat discharge curve of LiFePO4 batteries (as below example), your inverter sees a voltage and keeps the % the same while the truth is the % is dropping even though the Voltage stays pretty constant until the bottom knee, or as Andy would say, Kneeeeeeeeee

This is just for people that like me have looked up and tried to find some clarity, above is my understanding and personal preference to settings.