Agree with mad_jock for the most of it. Recently had the nasty experience of being nearly without any charts as the only powersource for both EFBs failed while one was out of juice to begin with. As the second leg was back to home base we didn't use the remaining EFB for that but briefed by heart, for any diversion we would have had to ask ATC to provide us with the minimum (all other info is kept within the FMC).