Re: [Phys-l] Fuel cell efficiency

[John Denker <jsd@av8n.com>]

On 02/01/2009 12:27 PM, kyle forinash wrote:

> I have read statements about fuel cell efficiency decreasing as more 
> current flows (Wikipedia) but I don't understand them. I

There's a super-simple explanation for part of that: 
internal I^2 R losses.  Draw the circuit diagram for
a black box containing an ideal battery plus some
internal resistance.

The I^2 R losses in the internal resistor count against
the thermodynamic efficiency of the black box i.e. the
real-world cell.