I have a nexus 6p running on Android 7.1.1 firmware. My problem is my phone used to be able to charge even when I was using chrome, watching YouTube, or even downloading large apps, but now the battery will be depleting rapidly at random intervals even when I'm charging via ac and not even using my phone. I've obviously done Google searches about it, and it appears that nougat is at fault, it did start occurring when I installed it. I've booted into recovery mode and wiped the cache partition from there, but that only fixes the problem temporarily, it comes back after a day or so. Any ideas? I've even got battery optimization on all apps. I do have a battery life widget on homescreen, if that could somehow be interfering with something else.

It also says "battery usage data not available" when I go under the battery tab in settings.