mains heater on 12 volt?

Discussion in 'The Projects Forum' started by tibbles, Feb 28, 2013.

  1. tibbles

    Thread Starter Active Member

    Jun 27, 2008
    i am rigging up a 240 volt fan heater and 1200 watt inverter in my vehicle to provide a few minutes of heat untill the vehicle heater decides to come to life,
    my question is, the heater is a standard 1kw, which is a bit high ,
    is there perhaps a way i could reduce the load to a more managable say, 600 watts.?
    i seem to remember in my dim and distant past, a capacitor being used to dim a flourescant,could something like that be a possibility?
    thank you

    ps (i cant run it from my home supply)
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    The amount of heat in a short period is too high to be effective without being dangerous. Not easy to control, if going that method, use an incandescent bulb hanging from the mirror so it is at least 6 inches from anything for a longer period (see timer, below, but be careful).

    Usually, a block heater on a timer to start about 3 hours before you plan to start the car is enough, the engine block/coolant will be hot, and vehicle heater will be blowing out warm air immediately.

    Lots of cars around here have one plug in under the hood, which hooks up both a 5amp automatic charger and the block heater. This is for when air temp is colder than -10ºF without windchill.
  3. dsk

    New Member

    Feb 24, 2013
    1 600W = 50 amps at 12V!
    You will normally not have a battery designed for such load.

    I use to let a 600W heater run (from mains) in 1-3 hrs to get a comfortable car.

    If you don't have supply from the mains, I will suggest heaters based on the cars fuel, or propane. Even when I have to admit to have used more dangerous ways myselves. In the the 80ies, I had a board on the passenger seat with a military liquid fuel stove running. (I went out starting the stove, locked the car and came back after a quick breakfast, I even let it burn while driving sometimes) I cant recommend the stove use, it may be really dangerous. :cool:

    Last edited: Feb 28, 2013
  4. crutschow


    Mar 14, 2008
    It would be easier (and not drain you battery so fast) if you used of these lower powered 12V heaters.
  5. t06afre

    AAC Fanatic!

    May 11, 2009
    I would recommend to use better clothing. Than a mains heater. The car will heat quite quick anyway. And as said you will drain your battery very quick. Not good in cold weather
  6. tibbles

    Thread Starter Active Member

    Jun 27, 2008
    thank you for your replies,a number of good points,i did look into the purpose built 12volt heaters, but in the uk anything over 150 watt is hugely expensive and as they are a bit weighty shipping costs from the US. plus taxes would be high,
    my thinking is for the short time it was on and of course it would only be on when the engine was running.
    (i suppose a car with headlights on main. rear and front screen heaters and the huge stereos prevelant today it would be close to 500 watts not to mention a caravan fridge at 20 amps.)

    safety is all important of course,i would be going direct to the battery with a 60amp fuse.and thick cables. the battery should be ok as it normally supplies a couple of hundred amps to the starter. the inverter has a number of safety features.

    thank you again doug
  7. t06afre

    AAC Fanatic!

    May 11, 2009
    Depending on what your need is. You can get a Webasto heater unit. They are not cheap but they do the job