Calculating Input vs Consumption query

Ako

My new AGM batteries are preforming well and I have accepted the anomalies i have been seeing are due th ethe differences between AGM and Flooded .

 Trojan give 24.45 volts at rest as being 50% SOS and In the mornings just before charging begins when batteries are at their lowest I am seeing 25.5v  while still having 63 Watts constant output so have no doubts I am within my target range . Some days I have added loads to see what happens , the Output increases as does the Input but always the same result , at the end of a days charging the output is greater than Input but early morning figures approximately the same .I know my equipment is showing the correct figures so i am searching for another explanation as to why my batteries are full by end of day and showing a good voltage early morning , if the input had been lower than output by now the morning figures and SOC would be much lower .

I had a thought last night that if correct would explain it but have no idea if it makes sense or total rubbish's so i thought I would run it by the members here and see what they say .

My Inverter displays a cumulative total for its output in What/Hrs and the Charge Controller shows input in Amp/Hrs so a common denominator has to be used which is what made me wonder if that was the explanation to the issue .

Until now I take the Output Watts and divide by 25v ( System/Batteries Average Voltage ) to arrive at Amp/Hrs to compare to the Daily Input figures . I wondered if it might be this conversion thats giving me the higher Output then Input figures so I have done the calculations using the appropriate figures for the time they are produce .

Output at night the Batteries average are 24.75v so the Inverters consumption figure ( W ) for that period I divide by 24.75 to get the Amps .

Output during daytime the Batteries average are 28.75v so the Inverters consumption figure ( W ) for that period I divide by 28.75 to get the Amps ..

Input from the Charge Controller is in Amps and the average Voltage while charging is 28.75 so I multiply the amps shown by 28.75 then divide it by the 25 volts .

The screenshot shows the application of both methods to yesterdays figures , rounded off to simplify things .

RCinFLA

Your use of 'Output' and 'Input' makes it confusing as to what you are looking for,

Watts, volts, avg amps, rms amps?

Inverters regulate their output AC voltage, so for a given output load power the lower the battery voltage the greater the required battery current.

All batteries have overpotential voltage slump with load current which is the energy the battery uses to create and move ions to meet the required battery current.  The greater the load current the more the overpotential voltage slump will be.  Any cabling voltage drop reduces inverter DC input voltage requiring more DC current from battery into inverter for given AC output load power. 

Then there are inverter losses.  Usually, an inverter's losses are greater the lower the input DC voltage because inverter losses are mostly component current flow losses and more battery current is required when battery voltage is lower.

Most battery monitors show average DC current, under the justification that it relates better to battery AH usage.

Actual battery current for a sinewave inverter is sine^2 waveform with 120 Hz ripple current for 60 Hz sinewave inverter, not a constant even DC current.  There is a lower level, near constant DC current drawn which is overhead used by inverter.  It is the no-load idle current required by the inverter for driving MOSFET's, powering relay coils, and microcontroller.  

Battery voltage times average battery current, plus any actual system losses, will not precisely equal AC output rms AC voltage times rms AC current.  The issue is use of average current on battery side.

Then, to be even more complicated, there may be AC output power factor for the inverter output AC load.  It causes higher peak battery current and greater inverter losses.

Photowhit

I think I asked in a previous thread about how you were measuring.

If you have a shunt based battery monitor, it's measuring the amperage going into the battery. An inverter will use some of the system amperage that will not cross the shunt while the array is producing current.

Ako

RCinFLA  , I appreciate your explanation and everything you posted but im afraid its all above me other then i think you demonstrated Inverter losses. I read it several times but still cant get my head around it . I may have a loss on the cabling from the Panels to the Charge controller but after that everything is measured by Charge Controler or Inverter with no losses , cabling is correct and very short runs . I need to compare what my Batteries receive via the Charge Controller and know what my consumption is to compare them on each cycle but so far all i see is that i have less coming in than im consuming , had it not been for the batteries performing as if they were replacing the consumed amount every cycle then i would know the reason but they show a healthy Min Voltage every day with the voltage never dropping below 24.5 v even with a small load coming out so the true Resting voltage will naturally be even better  . Unfortunately i cant compare like for like as Charge Controller displays cumulative totals in Amp/Hrs and the Inverter displays them in Watt/Hrs . 

Photowhit , are you saying that there will be current used and shown on the inverter that will use some power that will never reach the battery . Not sure if that would explain anything , i use a Busbar and everything is connected direct to it , Charge Controler , Inverter , Batteries and Battery Charger,  I don't have a Shunt , I am using a combination of Charge Controllers for the input , i have 2 x TS60 and took only 5 mins to change them over but they both gave same results . I use the Inverter which with no output shows 25 watts consumption and a Watt meter to check everything im consuming in total and individually by switching something on and checking the consumption rises in line with the declared consumption on its label and the Watt meter and everything appears to confirm the figures meaning i am consuming more power then im am producing while the behavior of the Batteries contradict that .

Friend said " dont fix something thats not broke " but i want to understand why i am seeing this . My system is small and simple and with good quality equipment that i trust so there should be a simple explanation , i just cant think what it could be .