Boondocking using HEATING PAD

X2 Roy Ken. It is VITAL that your inverter be PSW PURE SINE WAVE. A MSW modified sine wave inverter will fail the control module of your heating pad almost instantly.

Your heating pad would (most probably) not stay on 100% of the time. However with losses in the system pretty much count on a 9-10 amp draw. Twelve hours of operation will FULLY DEPLETE (to 50% remaining capacity) a pair of group 24 cyclable batteries if the pad duty cycle is 100% I've never seen an inverter gobble less than 2 amps vigorish.

Sigh. A propane powered heating pad. Sigh.

You might go the old-fashioned route: hot water bottle. Or maybe those hot-or-cold gel pads you can buy at the drug store. I've used a flexible flask with warm water in it; never had it leak.

You can also get chemical "hand warmers" at sporting goods stores. Put one inside a sock (not while you are wearing the sock) so it cannot come in contact with skin and use it like a hot water bottle.

Just make sure your INVERTER is the PURE SIGN WAVE type. The MSN INVERTER may cause your heater pad controller go up in BLUE SMOKE...

Your 70WATT Heating pad will draw around 5AMP DC from your two batteries. You need to look up the battery specs and see how long your can safely pull 25AMPS from your two batteries.

A TROJAN 27TMX 85AH 12VDC battery is rated to produce 25AMPS for 175 minutes or 2.9 hours. Two connected in parallel will produce 25AMPS for a good 5.8 hours. Your trailer will also have some parasitic power drains and of course you will be running some 12VDC lights at night. I would be running my HDTV and a few other home entertainment items as well... You really need to find out what is going to be on and add up the power drains.

In addition if you run down your two batteries over night it would be wise to have a way to quickly re-charge them as batteries sitting in a fully discharged state for a long period of time will do internal damage to your batteries requiring replacement.

To be successful you need to do some more planning and possible upgrades to smart mode converter/charger and LED lights etc. You also may need to have a small 2kW Honda type generator to connect your 30AMp SHore Power Cable to and recharge your batteries to their 90% charge state the next morning so you can can use them again the next night etc... If you have smart mode charging technology you can re-charge your two batteries in a short three hour generator run time. I do this at 8AM each morning during breakfast and this is when I make my coffee for the day when the generator is running...

I was never lucky just going to the woods and turn on things without planning and perhaps a couple of trail runs in my back yard. It always got dark on me around 10PM...

Roy Ken

For starters, your batteries are not true deep cycle.. they're hybrid marine cranking batteries..

I'm not even going to attempt the math but I would imagine someone will need to know what setting you plan on using on the heating pad. The one I use has 4 different settings.

If you're just trying to stay warm at night (as opposed to treating an injury), invest in a mummy bag and mummy liner.