R.W.
Hi there,
I did a search there are people looking for this same thing with much difficulty. I did find one but it is expensive and last for only 2-4 hours. But I would imagine your brother would think it is well worth it on certain occasions. www.BatterySpace.com in the search box type blanket. They have one for $198.00 battery time is 2hours. The one for $398.00 lasts 4 hours. But say he where going to watch a parade in the cold the 2 hour one would be welcomed I am sure. Also, at Lands End the Polartec blanket was said to be very warm also, high wool lined boots. I hope this gives you a start.