Heated Clothing

[Gordonrgs]

Hi everybody, I'm doing a few days touring in Scotland within the next week or two, and as it's likely to be a bit chilly I'm thinking of investing in some heated clothing, probably just a bodywarmer/vest and maybe some gloves, but I have a few questions:-

Anybody use this type of thing and have any recommendations as to what's good?

Will it drain the battery (Gen 1)?

Thanks