Cheap authentic battery packs to harvest 18650 cells

Put only 1 on the charger for about a minute or two. Take it off and see if it charged up to over 3V. Then try another minute or so and see how it goes.
I got an old Li-ion pack for a Milwakee drill that had 5 Sony IMR’s out of a recycle bin. They tested at only 0.3V and after charging them up, they seem OK. Maybe IMR’s are different though.