They may well have had a turbine but at CEBIT in 2007 they demo'd a methanol fuel cell laptop.
They also demonstrated a methanol fuel cell powered cell phone prototype in 2009.
The Military have been using fuel cells for communication devices (radios, sat phones etc.) for a few years at least now.
All the above demonstrate prior art as I find it inconceivable that no other fuel cell user/manufacturer monitor current and voltage to determine cell state.
Perhaps Apple are different in that theirs has to be fed Lattes?