My MBP15 (8,2, Late 2012) doesn't normally charge or draw power from a 45W adapter (from a 2008 MBA), with one exception:
- First, plug in the 85W power adapter;
- Second, switch the adapters quickly.
Following this procedure the MBP15 draws power form a 45W without any glitch for light usage.
Q1: Why is this procedure necessary and how does it work?
Q2: Is there a way to skip step (1)?