I wouldn't plug into or charge from your computer. You probably have a socket nearby
that you can use to make sure you don't damage your computer. It happens now and
then.
Also, from my experience, I would prefer not to a passthrough/charger that hooks on
to a connection on the end of the batter - like a small USB connection. From picking
them up and moving them around, the don't take too long to wear out - and then you
are ewed-scray.
I would charge my main batt while I was using a separate true pass through at my
computer or wherever. It all comes out in the wash. WAIT! I don't mean you should
put it in the wash!!