Building a 12v heater for my car

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SUMMARY

This discussion focuses on upgrading an antique car's rear defroster by incorporating a heating element to improve cabin air warmth for defogging windows. The user proposes using a 1 to 2-ohm resistor rated at 200 watts, drawing approximately 7 amps with 12 gauge wire, but expresses concerns about the size of the resistor. Alternatives suggested include using a compact heating solution such as a Halogen 12V 100-watt lamp or a similar device that can reach 150°F while fitting into limited space. Safety precautions, such as a fusible link, are recommended to prevent fire hazards.

PREREQUISITES
  • Understanding of electrical resistance and power calculations
  • Familiarity with 12V automotive electrical systems
  • Knowledge of heating elements and their specifications
  • Basic skills in automotive modifications and safety precautions
NEXT STEPS
  • Research compact heating elements suitable for automotive applications
  • Learn about the installation and safety of Halogen lamps in vehicles
  • Explore the use of fusible links and other fire safety measures in automotive wiring
  • Investigate alternative defrosting methods for classic cars
USEFUL FOR

Car enthusiasts, automotive electricians, and anyone looking to enhance the heating efficiency of vintage vehicles while maintaining a factory appearance.

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I am trying to upgrade my antique car while still keeping the factory look

The rear defroster is a blower motor that sucks in cabin air and blows it onto the back window. The air in the cabin has to get warm before the windows will defog.

I am thinking of helping that a little by installing a 1 to 2ohm resistor rated at 200 watts. It will run around 7 amps and will use 12 gauge wire. The blower will blow air over the resistor and heat the air.

Will this work?...the only thing i don't like is how big the resistor is...its 7x3 inches

i really would like something to do the same job at 4x1 inches as space is limited or really as small as i can get and still have some good heat...im replacing the hose that goes from that blower motor to the duct work with metal pipe...so all of it needs to fit into that space

is there any other more compact way to do this that i haven't thought of?

i did find something like this
http://sunelectricheater.com/ that was 1/8 inch wire that got red hot to 1400°F need something like that that gets to 150°F
 

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you might try a little Halogen 12V 100 watt lamp, or a couple 50's. they're easily replaced and you can get sockets for them... look in lighting dept at hardware or auto parts store... they sell them for closets and off-road lights.

but put in some precaution against fire if your air intake gets blocked. fusible link?
 

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