I have the exact same issue on my Macbook Pro Late 2013, and this is the second battery I’ve received from iFixit. What I’ve notice isn’t just the sudden drop in charge from about 50% to 7% but also the reverse when charging, as it will jump from about 65% to 100%.

Has anyone else experienced these sudden drops in battery charge from iFixit batteries bought lately? If so, what is the brand of the battery maker? My current original Apple battery is from DynaPack (labeled as DP), which can be easily seen with CoconutBattery but also under Apple’s System Report in macOS. I’ve contacted the iFixit help desk and they guarantee their batteries with a two year warranty. One of their suppliers is Simplo, which I believe supplies Apple with OEM batteries as well. My feeling is that whatever batteries don’t pass Apple’s quality assurance tests get knocked down to lower quality replacements, among which these iFixit batteries which have these sudden drops. However I have some faith in iFixit products since they are willing to stand by their products with a two year warranty. Any thoughts?