Using an auger on a battery powered Makita drill and repeatedly drilling hole after hole puts a battery to the test. And the result for Yani's generic batteries was early failure. Yani was customer number 1.
Yani is the reason all cells are welded in 4 places per contact.
Seriously, it was me that melted the contacts on the battery ends. I had the auger on the drill and was planting a row of "colour" and not messing about much between holes. A heavy load on a drill with near continuous use for 10 minutes. And this Makita drill has some guts so it draws a decent load.
Before the rebuild and battle hardened batteries Mark constructed, the auger was killing batteries faster than eBay could deliver them. Mark has identified an issue with these cheap generic batteries, thin metal contact straps with insufficient welding causing the straps to become detached. The batteries Mark rebuilt have thicker straps and 4 weld points per contact. They have excellent power and have stood up to my abuse so far.
[Shoot a video for here]