Battery charger status

Hi! this is my first post.
Yesterday i recieved my DSO Nano, and im trying to understand all the possibilities it has.
One of my concern, that i think its not explained anywhere, is the charge status.
If i connect the DSO to a USB, it seems like it has to be powered on to start charging. is this correct? thats a very bad idea, why having it turned on to charge?!
my other concern is how i know when the battery is fully charged? because when conected to USB, the battery status icon doesnt show, and i have to disconnect to see the charge, and reconect to keep on charging. that is another bad idea. but i think this could be fixed with minor firmware modification.
beside this, its a good investment for its price!
Thanks for your answers!

Thanks for lifting the concern, we need to improve on the details. Actually it is not a fragile product, you could plug it as long as you like, it will stop charging whenever full. Thanks!