Cig Lighter USB Charger - engine on to charge?

[-B-]

If you’re running a USB charger from the cig lighter, does the engine need to be running for it to charge?

Plan on one of these, to run a mini-camera, when the car is unatended:
http://www.wilko.com/car-accessories/wilko-car-charger-single-usb/invt/0344967" onclick="window.open(this.href);return false;

 

[-B-]

Works fine with engine off