Measuring current draw of battery powered transmitter or receiver

Date Updated: September 17, 2017 FAQ #2904
My Shure battery powered product seems to use batteries too quickly. How do I measure the device's current draw to make certain it meets specifications?

Here are step by step instructions:

  1. Determine the proper current consumption (draw) for your product. Look in the User Guide for this specification or contact Shure Applications Engineering. For this example, assume the device is a Shure wireless transmitter that uses AA batteries and that the specified current draw is 180 mA (milliamps).

  2. From a local electronic supply store, obtain a digital multimeter, some test leads with small alligator clips, and fresh AA batteries.

  3. Set the multimeter to mA and make certain to connect the leads to the correct jacks on the multimeter. Image

  4. Insert one AA battery into the transmitter.

  5. Connect one of the test leads between the remaining spring in the battery compartment and the black lead going to the multimeter.Image

  6. Lay the positive end of the second battery into place.Image Image

  7. Hold the red lead from the multimeter onto the negative end of the second AA battery. Image

  8. Power up the Shure device and measure the current draw. Current draw typically can vary by as much as +/- 20%. A current draw within this +/- 20% window is acceptable.

  9. To calculate how long a fresh battery should last, divide the current capacity of the battery by the current draw of the device. In this example, a AA alkaline battery has a current rating of 1400 milliamp hours; the device draws 173 milliamps. 1400 divided by 173 equals 8 hours of operation. This would be the maximum operational time that the battery could supply; it will be likely be less.