On Wednesday, October 10, 2018 at 3:02:53 PM UTC-4, micky wrote:
Why is this, charging and using battery pack at the same time.

3 out of 4 answers say it's bad. Why? or why not?

https://www.amazon.com/ask/questions...dp_dpmw_al_hza

And what is "PD capable".

You'd have to ask the designers. Without them saying or knowing the
internals of the design, no way to know for sure. One reason could be
it would try to draw too much power to do both, but it should have
protection for that. It might simply be that it can't do both effectively
at the same time for typical expected loads, so they don't want customers
to try to do it, expect to be able to do it, etc.

As Adrian pointed out PD is the new USB-C power delivery spec.