Each panel has 2 meters of carbon tape connected in parallel 2x1m and has an independent power button. It takes about 3A under 12V (36W) for each one or 72W together.
You can sew wire to carbon tape to make a good and flexible connection. The contact place shouldn't be hotter than the tape itself. If not you must increase the contact area. Sewed contact is very flexible.
On each panel sewn 4 pieces of Velcro . Now I can combine them into a single heated vest . A bit like a bulletproof vest. It's very soft and thin. Due to Velcro this vest will be comfortable to wear for a big man or a small woman. Each panel can be used independently with any clothes.
On the inner surface of conventional jackets I sewed 4 pieces of Velcro.
Now I can at any time fix the heating panel on the jacket and make it a heated jacket. It is fully warmed up to 40 degrees in less than one minute.