Heated clothing, such as vests, work with electrical, chemical or stored heat. The most common method of heating vests is electrical heat generated from batteries. Manufacturers typically make heated clothing for people to enjoy outdoor sports in the cold weather. As such, some heated vests are made to be plugged into a motorcycle or snowmobile to generated maximum heat in the coldest temperatures.
More common are vests with rechargable batteries, typically either lithium or nickel metal hydride batteries. The actual heating elements depend on the manufacturer. For example, Volt employs a system of heating panels made of stainless fibers woven onto insulated fabric. Thermal bonding tape gets wrapped around the fibers and connectors. The vest offers three options for level of heat, with lower levels increasing the battery life.
Gerbing patented a microwire heat technology that's even used by the United States military. The mesh consists of microscopic stainless steel strands wrapped in a Teflon-derived coating. Because there are so many of the tiny wires, the mesh heats instantly.
Different companies sell vests with the Gerbing microwire heat technology. Cabelas and The Warming Stone are two stores with heated vests using Gerbing's heating system.
A few vests use either stored heat or chemical heat. With stored heat, wearers must heat gel packs in the microwave and store them in pockets sewn into the vest. Vests with a chemical warming system also have pockets, but they're designed for heat packs containing activated carbon, iron, cellulose, water, vermiculite and salt.