Joulescope is an accurate, low-cost energy meter that measures
voltage and current to compute power and energy. Unlike other low-cost
solutions, Joulescope has a high sampling rate and bandwidth so that it can
capture events such as interrupt service routines. Joulescope is designed to
have only a 30 mV drop internally (the rest of the drop is due to cables and
connectors) to minimize static measurement disturbances. Joulescope also
automatically switches ranges quickly to minimize dynamic disturbances.
Banana jacks and plugs can carry more current which results in lower
voltage drop for the measurement system.
However, noise performance of the individual wires can be a problem.
Individual wires are subject to larger current loop area which induces larger
currents in the presence of electromagnetic interference. Radio waves,
electrical fields and magnetic fields are everywhere, and they can easily cause
current noise in the nA range. Using BNC connectors and coax cable improves
the overall system noise performance. If you are not overly concerned with
noise performance, you can use a BNC to banana jack adapter, such as the
Cal Test CT2410 BNC(M) to 4mm binding post adapter.
Joulescope also supports different front plates, including a BNC front plate,
which give better noise performance when needed.
For many applications, banana jacks are good enough. BNC connectors (really
coax cable) are more difficult to work with than plain wire. The center
conductor of coax is also much smaller (meaning lower current capacity) than
what is supported by banana jacks.