this might be a stupid question. are internal desktop hard drives ac or dc?

i was looking at electric car batteries, thinking what the hell, they run cars?

http://www.foxxpower.com/Foxx%20Power%20Specs.pdf

the biggest problem i found in what i originally envisioned is that cheap internal hard drives consume so much power compared to expensive small capacity laptop drives.

http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf

http://www.seagate.com/docs/pdf/datasheet/disc/ds_momentus_7200_2.pdf