Even genuine batteries fail, if your device can't cope (eg shutdown) with batteries with low current/voltage then it's defective. Then it's a case of testing

Even genuine batteries fail, if your device can't cope (eg shutdown) with batteries with low current/voltage then it's defective. Then it's a case of testing the battery is providing the right current/voltage and continuing. iPhones at least can cope with defective batteries, by throttling the processor, so presumably other companies can do the same and just not try to hide it from users.