Measuring Battery Voltage
Battery voltage is measured with a Voltmeter. If you are using a multimeter, you will need to switch the measurement setting to Volts or V. Again, be sure to note that the expected voltage should not be higher than the range selected on the meter.
To measure Volts, connect the black negative probe of the meter directly to the negative terminal of the battery, and the positive red probe to the positive terminal of the battery you wish to measure.
You can measure the battery in or out of circuit, although measuring the battery voltage with additional circuitry creating a load may affect the reading.
Be sure to note that the expected Volts in the circuit should not be higher than the range selected on the meter. If in doubt, use a high range to get a rough reading, then select a smaller range for more precision, as you have an idea of what result to expect.