@arossi143 , Alise Rossi , when you sent back the 1st UE boom 2 did you also send the charger, if still using the original charger from 1st boom, this could be the issue faulty charger, try a different charge method perhaps. UE says that you'll get 15 hours of battery life from the Boom 2, from a 2.5-hour charge through that micro USB port with the bundled 10-Watt USB wall charger and flat cable. Maybe you are overcharging by leaning plugged in 12 hours, so try the 2.5-3 hour charge a few times to see if it makes any difference. Also try turning(reducing) volume to say a third and see if it last longer, some forums state the battery performance greatly reduce when volume on in higher range.
There are two ways to check your speaker’s current battery level. Button press, Press your speaker’s ‘plus’ and ‘minus’ buttons at the same time. An audio message will play telling you the current battery level.
Open the UE BOOM app.Tap the +/- area on the UE BOOM on the home screen to display the battery life while your speaker is on.
If your battery level are showing full and speaker is not living up to your expectations return under warranty for repair/replacement/refund. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.