Voltage regulation, the ability to maintain a fixed voltage under different load conditions, can be evaluated with a voltage regulation calculation known as load regulation. The load regulation calculation requires that you know the voltage of your battery or voltage regulator under a full load condition, the condition that exists when all the connected electronic devices are on. The calculation also requires that you know the voltage of your battery or voltage regulator under a noload condition, the condition that exists when all of the connected electronic devices are off.
Things You'll Need
 Calculator
 Paper
 Pencil
 Voltmeter
 Battery
 Voltage Regulator

Determine the noload voltage of the battery or voltage regulator. Measure the output voltage of the battery or voltage regulator when there are no electronic devices attached. Conclude this is the noload voltage. Use for this example a noload voltage of 12 volts.

Determine the fullload voltage of the battery or voltage regulators. Connect all the electronic devices that the battery or voltage regulator must power to the battery or voltage regulator. Turn on the electronic devices. Now measure the battery or voltage regulator voltage. Conclude that this is the fullload voltage. Use for this example a fullload voltage of 11 volts.

Calculate the change in voltage. Subtract the noload voltage obtained in Step 1 from the fullload voltage in Step 2. Conclude for this example that the change in voltage is 1 volt, since 12 minus 1 is 11.

Calculate the load regulation. Divide the change in voltage obtained in the previous step by the fullload voltage. For this example, calculate that the load regulation is 0.091 volts per volt, since 1 divided 11 is 0.091.

Calculate the percent load regulation. Multiply the load regulation in Step 4 by 100 percent. Conclude that the percent load regulation is 9.1 percent, since 100 multiplied by 0.091 is 9.1
Tips & Warnings
 Voltage regulators are devices that are used to keep the voltage constant under varying load conditions. Most manufacturers of voltage regulators provide a load regulation specification. That load regulation specification is calculated for a specified full load. The manufacturer might specify that a 12voltage regulator has a 0.1 percent load regulation for a load current from 0 milliamperes to 300 milliamperes.
 A load regulation specification of 0.1 percent means the manufacturer guarantees that the output voltage of the regulator will not drop below 11.98 volts as long as the current required from the regulator is less than 300 milliamperes. The fullload voltage of 11.98 volts is calculated by substituting 0.001 (0.1 percent) and 12 volts into the calculation and then solving for the fullload voltage.
 Load regulation (percent) = 100 x (voltage no load — voltage full load) divided by voltage full load.
 Line regulation is another measure of voltage regulation. Line regulation is the amount of voltage variation from the output of a voltage regulator, or a transformer, that results from a change of voltage at the input of the voltage regulator or transformer.
References
 Photo Credit the old electronic device image by Andrey Khritin from Fotolia.com