see also:

• heaters for camping
• keeping warm when camping or hiking

• there are various types of 12V “electric blanket” / “heating pads”
• heating pads here are defined as those you place on your mattress and thus you lie on top of them
• low output 45-50W electric blankets can generally be used as lower output heating pads or as throw rugs and most of these will have a 45 minute timer
• car seat heated cushion pads are more robust and compact but are shorter and have longer cycling periods of 5 minutes which can result in getting a touch too warm and then too cold
• for overnight hikers, consider small 5V USB powered pads

• ElectroWarmth T36 mattress pad
  • $AU122 Made in USA - may be available on Amazon.com.au
  • 75W 7 power settings, “3.1A” on lowest setting, 6.5A on highest setting.
  • no auto-off (can get separate controller)
  • MUST NOT be allowed to scrunch up or be folded whilst on as risk of fire!
    • hence requirement to:
      • secure to mattress such as via safety pins to attach to mattress etc
      • not use with insulating material such as sleeping bag on top of mattress
      • ensure it is turned off when not in use
  • can be hand washed as long as controller does not get wet - risk of shrinkage!
  • they advise to cover with thick quilt to protect it from sweat and dirt - not sure how this differs to a sleeping bag that has been crushed by the weight of your body!
  • auto off seems to occur at around 11 hour mark
  • heat settings and power usage:
    • Setting 1: seems to run at <3A when ON but has long OFF periods so gives minimal heat
    • Settings 2-7 run at 6.5A when on but the proportion of time it is on increases as setting increases until constantly on at level 7 when it hits surface temp of 48degC but will drain your battery quickly - great to get warm quick in 15 minutes but then turn it back to setting 3 or so!
      • Setting 2 On 1 sec Off 1 sec so average is around 3.1A?
      • Setting 6 On 2 secs Off 0.5sec
  • not as power efficient as a car seat heater pad as it is much wider than your body and the heat is more spread out but it does provide continuous heat instead of the annoying 5 min off cycles

• Kickass blanket 3 settings
  • $AU69 1.9A, 2.85A, 3.8A (46W) with 45min auto off
• many others online - some with only 1 heat setting, some with 2-3 heat settings.

• shorter and stiffer than electric blankets (need two for upper body and legs)
• most have peak output at around 48W but average 1-2A power usage as they cycle on and off in 5 minute cycles
• usually have two heat settings
• will raise 2P fabric enclosed tent temperature by around 2-4degC as well as providing direct heat
• there are plenty on Ebay