When I was playing the demo I noticed my energy doesn't drain while getting shot in armor mode. When you view that little clip that goes with the perk (energy drains slower in armor mode) the energy bar is going down in that video where as in the game it does not go down for me unless I run or use strength while aiming down the sites.

Not sure if this sounds very clear. I meant the energy should drain more abundantely while in armor mode as you are shot. My energy still went down while in armor mode but the drain time didn't matter whether I was getting shot or not.

Yes it's supposed to drain energy while in armour mode.

It drains all the time to prevent people from keeping it on 24/7.