Abstract: A test system includes a test and measurement instrument having one or more inputs for receiving one or more signals to be measured or tested, a display for outputting measurement results or test results, one or more processors for operating the instrument, a chassis housing the instrument, a power connection to receive power for powering the one or more processors from a wall connection. The test system further includes an external battery pack separate from the test and measurement instrument and structured to mechanically and electrically couple to and decouple from the test and measurement instrument, the external battery pack including a DC power source for powering the one or more processors. The test and measurement instrument includes no batteries or other power storage device for powering the one or more processors within the chassis of the instrument.