I have noticed some electric heating pads for outdoor clothing. I would like to run it off a 12v battery sometimes and a 7.4 li-ion battery pack other times. I propose to cut off the usb connector and put a 3.5mm audio plug in its place. This is a description for one such package: Type:1 for 5 heating cloth Voltage:5V-12V Power:9 watt Three gear temperature:30—50 degree https://www.ebay.co.uk/itm/5-Pad-US...m=232962928211&_trksid=p2047675.c100005.m1851 I am a bit surprised at the acceptable voltage range. Should it work equally well at any voltage between 5-12v?