In the past year a whole world of non-genuine Li-Ion batteries seems to have come on the market to suit the main power tool manufacturers. These typically sell out of China on eBay for 1/2 the price of a genuine article. They even look like the real deal apart from missing trademarks.

I am well aware you get what you pay for in this world but hey, who knows maybe these are a good thing. So has anyone had any experiences with knock off Li-Ion power tool batteries?