No. The heating system in the coat is self regulating and cannot overheat if used normally and according to instructions with our 12V battery. Using a higher voltage could increase the heat and therefore this is not recommended.
The coats starts to heat immediately and all panels are to full temperature within a few minutes. The heat panels are surrounded by a thin layer of wool so the heat stays within the coat when the battery is detached. The outside temperature will determine how long it takes to cool down.
Because the technology is self regulating it is a balance between the temperature setting of the technology and the external temperature so it will always be a range. On the lowest setting it can heat for up to 8 hours. If you would like an extra battery add £50 or US$85 to your pledge.