I have a vague plan to make some heated clothing and I wanted to check whether I'm approaching it the right way. The heated clothing you can buy is generally designed to be worn as an outer layer but I think that's a pretty inefficient route compared to heating an inner layer and trapping the generated heat.

For the heating elements I want to use carbon fiber cloth cut into strips. You can buy carbon fiber fabric in a narrow format but it's more expensive than buying 36 cm x 91 cm and cutting it into strips. Cutting my own strips will also allow me to control my resistance per meter. I will use a sewing machine to sew these carbon fiber strips onto the outside of some cheap long-sleeve t-shirts and "long underwear" aka long johns.

I would like to use two of these power bank boxes which accepts four 18650 batteries and produces up to 2 A at 5 V. This would only be 10 W per clothing item but alternative methods of obtaining power are more expensive and/or more effort. There's a 3 A box but it's much more bulky. Maybe I could tie together the positive and negatives of the insides of two of the 2 A ones to get 4 A (I'd want them to both cut out about the same time).

I will attach the power bank boxes to a belt and find a way to sew some USB cables securely onto the clothing (technique called couching, I suppose). I guess I'll put them in a pillowcase in order to wash them.

 

I have a vague plan to make some heated clothing and I wanted to check whether I'm approaching it the right way. The heated clothing you can buy is generally designed to be worn as an outer layer but I think that's a pretty inefficient route compared to heating an inner layer and trapping the generated heat.

For the heating elements I want to use carbon fiber cloth cut into strips. You can buy carbon fiber fabric in a narrow format but it's more expensive than buying 36 cm x 91 cm and cutting it into strips. Cutting my own strips will also allow me to control my resistance per meter. I will use a sewing machine to sew these carbon fiber strips onto the outside of some cheap long-sleeve t-shirts and "long underwear" aka long johns.

I would like to use two of these power bank boxes which accepts four 18650 batteries and produces up to 2 A at 5 V. This would only be 10 W per clothing item but alternative methods of obtaining power are more expensive and/or more effort. There's a 3 A box but it's much more bulky. Maybe I could tie together the positive and negatives of the insides of two of the 2 A ones to get 4 A (I'd want them to both cut out about the same time).

I will attach the power bank boxes to a belt and find a way to sew some USB cables securely onto the clothing (technique called couching, I suppose). I guess I'll put them in a pillowcase in order to wash them.

What is the electrical conductivity (resistivity) of your cloth? We can calculate once we know more.

Also, most electrically heated clothing is meant for outer layers (at least second layer) because there is high risk of skin burns from localized heating. You will need current sensing and/or temperature sensors to make sure the potential victim does not become a real victim.