enlarge/ the iphone 6s and 6s plus.andrew cunninghamshare this storya couple of months ago, apple acknowledged that some iphone users were experiencing unexpected shutdowns—their phones would turn off before the battery was fully discharged and could only be turned back on if plugged in. these problems primarily affect the iphone 6 and 6 plus and 6s and 6s plus.apple released some fixes in ios 10.2.1 in late january, though the company didn't specifically mention battery or shutdown issues in the release notes. but now that the update has been out for a while, apple told techcrunch that it had fixed 80 percent of the issues for iphone 6s users and 70 percent for iphone 6 users. apple says ios 10.2.1 has been installed on about half of all compatible idevices, so if you have one of the affected phones and you've noticed problems, fire up your updaters now.the report says that the problems were caused primarily by older batteries—spikes in power draw could make these batteries `d...