This is the first time I have heard of this type of intensely positive reaction. I really do not know anything about it. I would speculate that, perhaps, you are experiencing very positive physical feelings as the result of a reduced pathologic inflammatory state.
But in my opinion it is not like charging a battery, and anything related to eddy currents would dissipate within a few milliseconds of the end of a PEMF session. So that’s probably not it either.
I certainly do not deny what you are feeling. I just don’t think it is the type of thing that many PEMF marketers claim, such as “charging mitochondria” or charging up the cells in your body the way a battery charges up. To me, that all sounds like marketing hype, not real science.
But the improved feeling of well-being during and after the use of PEMF is certainly real. I have that experience every day. And it is OK if we do not yet have a good scientific explanation for it. This is often the case. For example, there is still no good scientific explanation for the human experience of consciousness, yet we all know it is very real.