I like to "car camp" in my 4Runner in the spring and fall in the Colorado Mountains. It's definitely too cold (and sometimes the ground is too snow covered) to sleep in a tent, so I'll fold down the seats in my 4Runner and sleep in the back. Even with multiple layers of clothes and a good sleeping bag, it can get pretty cold. Not to mention, a mummy bag won't help out my pooch, who I usually bring with me and who doesn't have the thickest coat.

I want to find out if there is a way to safely warm the interior of my 4Runner without 1) draining my battery and 2) creating a fire/CO2 hazard. I've read info on several portable heaters, however, most are not suitable for use inside of a car due to CO2 and fire hazards. Infrared heaters might be an option but even a lot of those require propane. I have even considered a heated blanket but most of those turn off after 45 minutes and could potentially drain my battery if used for too long. I was wondering if anyone had any recommendations for a heater I could use inside of my 4Runner that is safe and efficient.

I think it will be hard to satisfy every requirement. When I don't use the truck heater I use a Coleman Black Cat catalytic heater which satisfies everything except the surface gets pretty hot, but no flame and no exterior surface gets red hot. The legs make it pretty versatile and stable inside the truck. It officially requires a very small amount of ventilation. I forget the amount but it's something on the order of the equivelent of cracking one window a half an inch or less. It takes a standard propane canister. In the pic, the door is open because of the jetboil not the heater.

Maybe I'll discover something I like even better in this thread.

check this little guy out. just might work out perfect for you.
12 Volt Rubberized Heater with Fan - Interior Auto Accessories - Automotive & Motorcycle

Both of these look like feasible options. I would be curious to find out how much amperage the 12v heater draws. My only concern with that option (or any option that requires the use of the car battery) is that I might wake up to a dead battery.

The Coleman Black Cat looks like a good option. I usually keep a window or two cracked when I sleep in my 4R for ventilation and to help alleviate condensation issues. How long can you run that on one propane canister? Ideally I would get 6-8 hours out of whatever option I choose, but I realize heating the inside of a car that is not running for that long presents some challenges.

Officially, it will run for 7hrs on a canister.

Honestly, I still bring it along when it's very cold, but only as a backup. I'd much, much rather use the car heater while idling. I'm convinced it does zero harm to the engine. Here's my citation for that:

How long can you idle on a tank of gas?

Apparently, CAT over heating is a bigger concern. Since I only do it in cold weather, I don't worry about that and I've accumulated many 10s of hours now doing it, but you could still just follow the manual and never let it go for more than 20 minutes at a time. There's nothing I would trust to let operate while sleeping, though.

Good point, JB. This kind of confirms what I had originally thought, and that is my car heater is probably my best option, even if it means waking up once or twice to in the middle of the night to fire up my engine and get some heat going.

And I agree, idling is overrated as far as what it can do to your engine. It might not be good to idle your engine for extended periods of time during the break-in period, but I don't get too worried about it after that. Not to mention, it is probably the most efficient way of providing heat and power when you are camping.

Just thought I'd mention that I went to go buy this same thing but when I got to HF I realized it was smaller than my hand..

Just my .02 I always thought this situation is where remote start would really come in handy. Just leave the heat in the "on" position and when you get cold in the middle of the night, just hit the remote. The truck will run for 10-15 minutes or whatever you have it programmed to, then it will turn off. No mess, no fuss!

X2! That sounds like a great idea! I didn't know you could program them to shut off after a set time frame, then I wouldn't have to worry about falling asleep with the truck still running.

Yup all aftermarket remote starters will run for a pre-set time and then automatically shut off. IIRC it's increments of 5 from 10-minutes up to half hour or so. Think about how soothing a magnaflow at idle would be!

Anyone have anymore input about a heater other than the truck heater to run inside when cold? I'm looking to ski bum in my 4runner for a month this winter.