Yes! Firstly, if u are using a specified charger that has correct rating for ur b3, u can use it while charging. And the b3 percentage will increase like you are not even using it.
Secondly, if your charger rating is below the capacity of ur ba3 cell, then u can't try that. Cos u might not get a +1% for hours because u are using it. In some cases, instead of the charging % to increase, it would decrease or stand still.
Thanks for coming around @rharphelle