Earlier this month, a sizable number of new Galaxy S4 owners in Germany started reporting problems with their batteries, from increasingly fast power drain to “swollen batteries” that expand to the point where they risk breaking open. Trusted Reviews originally reported that Galaxy S4 return rates were up to 30% for some German mobile phone carriers, thanks in no small part to the battery issues. On Wednesday, less than a week after the original report, Samsung issued a response to Trusted Reviews and said that it is aware of the issue and that it promised affected users that they will receive replacement batteries free of charge.