That's really interesting and I never thought much about this before. The 2018 Gen2 Volt has an acceptance rate of 3.6kW, the earlier models were 3.3kW I believe.
Whenever I charge my car with my Juicebox, the amperage gauge has always displayed a steady reading anywhere between 15.9 to 16 amps, not 14amps. And the acceptance rate is not always 3.6kW as I would have expected. Here's a screenshot from the JuiceBox Control Dashboard:
The amperage and voltage has some variance but P=IV and it does work out to 16A
Assuming 3.6kW which is the spec acceptance rate, it actually would be 15amps*240V=3600.
Are the JuiceBox gauges off (which would be really odd), or is the difference due to some sort of efficiency loss?