I had the exact same thing on a MacBook Pro (13-inch, Mid 2012). Installed the new battery, and my computer flips off every few minutes—once right in the middle of booting it back up. Tried and SMC reset twice, just in case I did it wrong. Let the battery completely drain, then charged all the way back up in case that was it too. It would do it regardless of whether the computer was charging or not. Below are coconutBattery readings. Update (01/27/2019): Looking at the timeline of posts, it seems like a rash of these happening in the last four months to Mid-2012 MBP batteries, which makes me think iFixit has some manufacturing glitch in a batch of these batteries. Especially since the manufacturing date of my battery is from June 2018, a couple months before the first problem of 2018 was reported on here.