[Lewis Thomson (OP)]

Donald is curious to know the science behind this idea.

"Humans do not run on batteries, however, how many AA batteries would equal the energy in a 1600kcal diet? Just wondering the equivalence between biological efficiency and a ready technical object."

Discuss what you think in the comments below...

[HannahC]

If we could eat batteries, we would hardly be humans. I think robots of something else, and they must produce more energy than human organism.

[vhfpmr]

To obtain 1600kcals (=6.688MJ) you would need 774 1.2V 2Ah AA cells (at 8640J each).

[Bored chemist]

To obtain 1600kcals (=6.688MJ) you would need 774 1.2V 2Ah AA cells (at 8640J each).

And (at 26 grams each)  about 20Kg...

Though 1600Kcal isn't much for an adult human. I'd expect to burn roughly half as much again, so I'd need about 30Kg of batteries.
And bathroom design would need to be changed...