I too have a 2015, out of warranty, > 100k miles. Battery fully charged had degraded to ~75mi. Got recall of wiring harness. A day after fixed, went into turtle mode and BMS error (never seen either before). Then KIA stated issue was fixed with a BMS "software upgrade". A day after, again turtle mode and BMS error. Then Kia took a few weeks to replace the battery pack with a refurbished one, now getting ~90mi on a full charge. But again after a day same issue. KIA has had the car back for 4 weeks stated a NEW battery pack was coming from Korea. It finally got here, installed and car seems to be running great. But the next day Kia asked for the car back for further investigation.