I sometimes use a 115vac heating pad powered by my inverter. It is about 16x24". Heats up much faster with more concentrated heat than the mattress heating pad. Draws about 4.5 to 5 amps on high This is a newer model which has a timer, because too many people fell asleep on the old type and burnt their skin and the nanny state stepped in.<br><br>Sometimes the electronic timer protests the MSW of the inverter and I need to unplug/replug or reset the inverter it to restart it after the timer runs out.<br><br>This model also states it is designed to be laid on top of a sore area, not under a sore back or neck, which is what I primarily use it for, and where I use it. i just make extra effort to not fold it and pinch the wires.<br><br>It is effective in warming up my core when sitting in a captains chair. I just hate listening to the inverter fan. I moved the inverter power switch so I can easily turn it off from bed, but to date have only needed this feature a few times and its location is more a hindrance to the other primary tasks I use the inverter for, like powering a soldering iron or angle grinder.