12 volt heaters

I searches for ages and found nothing good, they all use so much power for very little gain. Ended up settling for some electric blankets that draw bugger all from my battery through a inverter.

DIESEL HEATER great in our Kimberley Karavan

Johno - forget using 12V for ANY serious heating appliance. You simply don't have enough energy in your battery to provide any useful heating.

Works like this :

Power (watts) = volts x amps

A typical small radiator at home will draw 1000 watts. Most electric jugs will draw at least 2000 watts.

How many watts in a battery? Well, its not quite that simple but lets say you have a 100 amphour 12 volt battery, which is typical for camping use. In principle, (though not in practice) this might deliver 100 amps for an hour. If it delivered this at 12 volts (which it won't) that's 1200 watts. So IF it could be made to work, it might run a small radiator for a bit over an hour. In fact though you will probably use an inverter between battery and heater in order to get 240volts - at 80% efficiency the inverter might be expected (though it won't) to deliver 1000 watts for an hour.

BUT - you should never run a battery fully down as that will seriously shorten its life. The sort of deep cycle batteries we use when camping will not tolerate being discharged at 100 amps - they will get hot and bothered and die. They will not deliver 12 volts when hit with heavy loads. Realistically, you will not get your 1000 watts for an hour out of any 100 Ah battery.

There are members here with BIG systems - some with over 200 Kg of batteries with lots of solar panels to charge them. These people do run jugs for brief periods and maybe heaters too, but they have invested thousands of dollars in their systems.

Suggest try gas for any heating job - far cheaper and very effective.

Please read Electricity for Camping. It will answer many of your questions about 12 volt electrics.

Cheers

John

We free camp mainly and make it a point to camp away from others (just thought I would clarify that before all the nay sayers start). We have 2 kids 7 and 3.5 and use a 1800 Watt 240v heater and run it off our Honda EU20i. It works a treat and the Generators these days are very quiet. It will run through the night on a tank of fuel (it also charges our batteries during this time).

I have 210 Amps of batteries and am considering a couple of electric blankets to run off the inverter, but I need to confirm how much they draw etc before I jump in. As stated discharging the batteries fully is not good for them.


Regards


Jas

Johno - I had Dometic diesel heater in previous van and it worked well. but it did not have a lot of use however I believe they are reliable and mostly trouble free provided clean diesel used. In my current Van I went to gas [Truma]. Google search gas heater caravan and you will find Truma easily. I have only used it a couple of times but it works very well, seems efficient and warms up 22'6 van within 20 minutes from freezing outside temp. Mate recently retro fitted same make model in half a day but he is experienced gas fitter and as you will appreciate there are strict legal requirement for specialised skills when working with gas. It is not rocket science to fit the units [12 volt power, remote switch plus gas lines and some ducting inside and an exhaust to outside], but you need the specialist tools and leak testing equipment/fluids to be absolutely certain it is safe so you must locate a licensed gas fitter, there are several in Melb area that do contract fit outs for custom van builders and will have fitted plenty of Truma gas units. The gas units are usually available [again search on line] and you will buy for less than $1800, fitting ought be less than say $400. Diesel heaters may be cheaper than gas now - not sure. I liked the fact that I did not need a extra tank for diesel. Some will prefer diesel for their own good reasons - choices!!!
Bob

As explained by other posters ,essentially you can not but there is a work around.

Now we use a primus gas heater - almost the only practical portable device around but before that we would run a couple of infra heat lamp globes which project heat onto the body effectively - like bathroom heaters.

These globes run off 24ov and use about 300w each (25 amps @ 12v) giving about a hours run of typical car battery setup via your standard 600w inverter.

Worked really well but for longers periods you then have to run of a gennie or have the car idling.

Have one running now at home in back yard as kids are working on a trail bike in the cold night air.

These guys sell Snugger SF2 remote
Not really sure how it works but its portable so might not need much install
http://www.dieselheatingaustralia.com/Products-and-pricing.html