My R7-371T has started spontaneously black screening on battery power when the battery still shows 25-35% power remaining. This has happened several times in the past few months. I usually use the computer with the power supply plugged in or on battery for a couple hours (not dropping below 50% power) and have never had a black screen under these conditions. When I occasionally use battery power longer and get below 35%, that's when the issue occurs.
When it happens, the computer goes from on to off instantly. There is no blue screen, no hibernation/standby, no crash log, no error message in Windows Event Viewer (other than a critical error message from the reboot that points to Windows Kernel Power with all bug check codes showing "0"). I've run the AcerCare battery diagnostic and used batteryinfoview, and neither indicates any problem.
I don't think this is a battery calibration issue, because if it were, I would expect the system to go into hybernation rather than spontaneous and instant shutdown. I'm leaning towards a battery cell defect because, if it were a motherboard problem, I wouldn't expect the problem to be isolated to battery only events and only when the battery is below 35%. The problem doesn't appear to be software related because it will shut down even if I'm not doing anything, and it always occurs when the computer is using only OEM hardware with nothing connected to it.
Any suggestions on further diagnostics that could be tried would be appreciated, but please don't suggest reverting to the factory disk image, reinstalling windows or running in safe mode. I have an identical R7-371T that I purchased shortly after buying the first one for use as a backup and I'm going to image my drive over to that machine if I can't figure out a way to further diagnose hardware on this one. This one is out of warranty, and while I'd be OK changing out a defective battery, I don't think it would be cost effective to change the motherboard.