We supplied the LP 12V batteries for the CityEL. 

These are the comments from the CityEL user: “More fun with a CityEL :)! I have a CityEL Fact Four Basic. My old 4x PB-Batteries 12V 80Ah has a weight of 110kg and the new LiFeYpo4 12V 80Ah only 48kg!!! 60kg less!! Rage exceeding - better speed increasing - lower current to claim mountains or during normal driving - cooler controller because of lower current during working - easy to install - easy to handle!”