New batteries charging very slowly

I purchased two new batteries (internal & external) from ifixit for my Thinkpad X240. After installing them, I charged them up for 8+ hours. One battery charged from 23% to 46%, and the second battery didn't charge at all from the 23% charge it came with. This seems unusually slow, I am using a 90W power adapter which charged my depleted internal battery from no charge to 100% in two or so hours. (original external battery was malfunctioning, so no base line on that. I tried removing the batteries and re-installing them in the device manager, but still no change in the charge rate. Does anyone have any suggestions/troubleshooting?