A:Answer The charging case has a battery built in to it. When you put the earbuds back into the case, even with the case NOT plugged in, it will charge the earbuds. Case has about 10 hours of battery life in it - so when earbuds are drained, you can put them in the case for an hour and they recharge. Great feature for when you are on the go and can't have the case plugged in. Obviously, before some trip (airplane, etc.), charge up the case.