Well, I wired up a test battery to the pcb, and it charged up. It took around 4/5 hours, which was as I expected, its an old 2.2Ahr battery and the charging current is limites to 500mA.
I took a few voltage measurements along the way to check it was actually charging, and it stopped around 4.2V.
Next step is to connect a recycled battery to it and take some proper voltage/current measurements. Then its finished and I'm good to bung it in a project.
Ive hacked apart my first Makita battery and extracted 4 candidate cells, the rest are nackered by the looks of it.