What is the worst invention invented in the mankind?

This is a pretty stupid idea! Visit this link for the photo: http://www.impactlab.com/wp-content/uploads/2009/03battery-charger.jpg

Battery-powered battery charger (1993) ... consumers were left scratching their heads after an inventor patented a simple way of recharging mobile phone batteries - with more batteries.

In 2006 Motorola reinvented the battery powered battery charger and gave the idea slightly more credibility with a charger that at least plugged into the wall. The P970 can be charged and then taken on the road as a second battery for gadgets with a USB input .