Hello, and thank you for your interest.
The Battery is located in an internal pocket of the jacket behind the left outside pocket on the side(by your hip), the controller is in the left pocket, as far as the weight goes you cant even notice that there is a battery in the jacket(feels like a cellphone) and the jacket liner itself is no heavier than a columbia jacket liner, when we go deer hunting i usually only wear this and one of those cheap zip up orange hoodies and i usually bring an extra battery with as well, it keeps me warm all day with out all the bulk.
here is a pic of the battery
I also forgot to mention that the heated jacket is wind resistant, you can wear it on a motorcycle, atv, or snowmobile, it will not only block the wind, but heat you up as well.
If you would like to try one and use up one of those discounts for placing a review we can have it to you in 5-6 days, any takers?
Thank you for your time,
Mike