allanhurst:
The you need a MUCH bigger battery. Your pad takes 3 watts ( 5 x 0.6).A good 18650 Li cell stores about 8 watt - hours, so would power the pad for > 2 hours with a suitable boost convertor.
How long do you want to heat the pad for?
Allan
2 hours sounds suffiecent because i will be turning it on and off so it will be off most of the time. Sessions the heat are on are on for 10 minutes