Measuring Power Efficiency and Power loss of a product

[danny davis]

At work I have to measure the Power Efficiency of our product

The Product runs off 120 VAC or runs off DC batteries , So we are going to measure the Power Efficiency of AC or DC batteries test, from the power input and power output

Power Output / Power Input X 100 = Power Efficiency or Poss Loss?

1.) I have to measure the Efficiency at load percentage of fully charging current of the battery

What is the formula for this?

2.) I have to measure the Efficiency at load percentage & Trickle Battery Charger

What is the formula for this?

How do you measure the "Trickle" of the battery charging? My manager said that the current should be in the millivolts supplied to the battery bank when measuring the Trickle of a battery or batteries

3.) I have to measure the Efficiency of the Battery

Which the formula is: Power output / Battery Voltage X current = power input X 100 = Efficiency?

 

[chuckey]

Power efficiency = REAL power in/REAL power out X 100%
1.) Starting of with a flat battery, measure the battery voltage and charging current every hour and real power in. Calculate efficiency at every hour, plot efficiency v. time .
2.) Load the unit to 100%, measure Pin and Pout calculate efficiency, repeat with load set to 90%, 80%. . .
For trickle charge, remove the load, leave on charge until the charger goes into trickle charge, measure Pin and Vbatt X I batt (Pout?)
"current should be in the millivolts ", current should be in milli AMPS. Trickle charging is when the charging current is just enough to offset the chemical degradation of the battery, so very low.
3.) Efficiency of battery, I guess is the ratio Pin/Pout. The problem is that you don't know how much power there is left in the battery. batteries should not be run flat but run down to some threshold voltage set by the battery manufacturers (who will know their storage efficiency). So flatten a battery down to its minimum voltage, measure Pin and battery V and I, every hour until battery charged. Put battery on load , measure V and I every hour until V is down to minimum voltage. calculate the total Pin and Pout. Work out efficiency as tot Pin/ Tot Pout.
Frank

 

[danny davis]

How do you measure the Trickle Charging?

 

[chuckey]

measure the current into the battery and times it by the battery voltage?
Frank

 

[schmitt trigger]

A battery stores energy, not power.

Batteries are usually rated in Amp/hrs....which could translate directly into energy (watt hours) by simply multiplying the battery voltage.

Unfortunately, the battery voltage does not remain constant as it is either charged or discharged.

Therefore, you have to measure voltage and current, multiply both to obtain power, and then perform integration it to obtain the energy.

You can simplify the circuit a little bit by using an electronic constant current load to discharge the battery, and only measure the voltage...whose value is scaled by the CC value and thereafter it can then be integrated.