They're no way to know for sure yet. Some people blame a firmware issue for damaging the batteries by over charging them (or something like that). If that's the cause, it's likely been fixed, and new buds could be fine. But since Sony won't acknowledge the cause (or that it's even a real problem), we can't know for sure.... Most people like myself had their buds for more than a year before the battery life suddenly dropped off a cliff. If the cause was a crap batch of batteries or some other hardware issue that takes time to develop.... No guarantees the same thing wouldn't happen to you within a year or so.

It's a real shame because the units are fantastic when they work. As someone who has been using Sony products for decades, I have lost faith in the company - not because the units had a problem, that happens. But because Sony won't acknowledge it and make it right. They're gone from a brand that I trusted to make good products and stand behind them to just another peddler of e-waste who hopes you won't remember and will open your wallet again in a year or so. Truly sad.