updated to big sur before doing the nvme upgrade with sintech adapter & Samsung 970 evo plus on late 2013 rmpb. Bootrom is on 427.0.0.0. Installed High Sierra 10.13.6 and went smoothly. The disk speeds are great - 1500 MB/s, sleep wake is fine and only 1% drain overnight. However - when im running unplugged, the battery drains incredibly fast. I would say ~20% in 10 minutes or so of light browsing/watching videos on chrome. I will caveat this and say I just replaced the battery as well with a newertech 72W and did the whole power cycle/calibration process. It's a clean install of High Sierra so I doubt spotlight is indexing in the background, I'm wondering if it's the NVME pulling a ton of power, or potentially an issue with the battery. If there's any way for me to monitor the battery drain?