FYI

I've used empower on most of the DL fleet (those that have it: 737-800, 764, 767 BE, 777) and want to pass on what I found:

The Empower curcuit will automatically shut down if you try to pull more than 80 watts. Many of the newer laptops will pull close to 110-120 watts if the laptop is on and the battery is charging. The way around this if this happens is to remove the battery. Without the charge, the laptop should only pull 40 - 80 watts.

Hope this helps!

PS, for what its worth, I carry a spare battery for all domestic travel and only bring the empower for international or vey long (5+ hours) flights.