Training power cords to behave and stay in nice coiled loops is easy. Elongated and kinked cables are the downside of buying them sold in hanks. And trying to coil them ends up in bizarre tri-cornered loops. But warm them up and coil them around a paint can for a few days. Then you can add some tie line or velcro and they will nicely trained in your coil bin. To warm what you see below, I set them on the floor and clamped a 500W flood light about 12″ above the pile of cable. 20 minutes later, they were pliable, but not too hot.
Pictured here are short commercial cords of small gauge (16 AWG) purchased from the local home center. These are 8′ and 15′ cords and damn handy for short runs between backstage gear or through a set piece to a small dimmer.