The only blinkers I've ever seen on a 50V were aftermarket Cateye brand signals. Operated by batteries in a small white plastic case, and controlled by a switch on the handlebar. Think they used 4 D-cells.
A while back, someone on eBay was selling sets of the large stalk mounted Cateye signals as 'Motobecane OEM'.
Can you show us a pic of your signals?