Saturday, 8 December 2018

heat - Dc heater that will/should blow hot air


I was just trying to lift a toy motor off the ground so mounted a toy propeller and tested it, i think it would have lifted(without battery weight) but i didn't bothered balancing it.


Final result was that it became a very nice little fan.


Coming to the point, winter is coming so i decided to make a heater out of it. i got 8x 2500mAh 3.7v lithium ion batteries (similar to those found in laptops). i use them as a powerbank. that makes about 20Amp. As a heat sources, i decided to use nichrome wire out of soldering iron(rated 25W) and tested it using about 8" piece of it. It worked fine. This is not my field so please bear with my calculations.




  • Power source : 3.7V lithium ion batteries 8x2500=20000mAh(20Amp), 74 Watt





  • Motor consumption : 11 Watt (1.3 Ohm)




  • 4 pieces of nichrome wire each with 3.5 Ohm resistence = 4 Watt




My questions are





  • can i use nichrome wire for this purpose?




  • should i use resistor to control heat?




  • can i produce enough heat using nichrome wire at around 16 Watt (4x 4 Watt pieces) for this purpose?




  • will my batteries last 2 hours of time?





And finally, is it a good idea?


Edit: i am not trying to raise room temperature, just trying to make it portable to make my hands or mostly feet warm using hot air.



Answer



74 W is just maybe enough to heat your hands and your feet, with forced air. but would only last <1hr


. a 100W bulb is even better. I would suggest a 750W interior winter car heater with a thermostat built in. quiet. or a ceramic heater....


Although you could make NiChrome wound socks with 2 Watts each;)


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