I brought one of these yesterday (got fed up wearing layers and layers) and went for a spin... ok it was more of a blast

at 10pm it kept me very toasty indeed, got hot when in slow traffic but not so hot to be unbearable and on the blast sections was very toasty (i was just wearing dragging jeans, a leather jacket, thin t-shirt and gloves) Its nice and well fitted , not at all bulky like other heatet waistcoats on the market. (mind you £180 is bloody expensive especially without coming with a temperature controller as standard or an on / off switch!)
Does anyone know if you can power 2 (1 for pillion) off the same bike battery? or is this not reccomended?