Things You'll Need
Instructions
Remove the RC battery pack from your toy.
Plug the RC battery pack into its charger and fully charge it for the time specified by the manufacturer. Completely charging the battery pack will ensure it has the maximum voltage possible in its current condition.
Disconnect the battery from the charger.
Turn on the voltmeter and then select the direct current (DC) voltage setting. Typically this is designated by a capital "V" with straight lines above it or the letters "DC." Frequently the dial will contain a number of DC voltage settings labeled by specific ranges. Make sure to choose the range that includes the voltage listed on the battery.
Place the red positive lead of the multimeter in the left hole on the RC car battery plug.
Position the black negative lead of the multimeter in the right hole of the RC car battery plug. Read the voltage from the screen. A negative value just means that you have switched the leads of the connection. Disregard the negative sign and compare the voltage to that written on the battery.
Replace the battery if the voltage reading given by the voltmeter is 10% more or less than what the manufacturer has specified. Multiply the voltage written on the battery by 0.10, then subtract the result from the original voltage to get the lowest acceptable voltage. For example, if the nominal voltage is 12 volts, the lowest acceptable voltage before replacement is 12 minus 12 times 0.10, or 10.8 volts.