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Calculate Resistor for Heating Wire Answered

Hi there,

My Goal is to use a piece of heating wire from an old hair dryer  (1.6 Ohms resistance for the length i want to use.)
and heat it red-orange using my old USB power bank. 5V output from an 3.8V lithium ion battery i dont want to mess with the circuitry inside.

Problem:
The USB Power Bank has short curcuit prevention built in, so when i connect the heating wire the power bank stops supplying electricity.
I found a 7.5 ohms resistor and connected it aswell, the wire became a little warm, the resistor incredibly hot but most importantly the power bank continued to supply power - success.

I would like to know what resistor i should use to get the wire red-orange hot but at the same time keep the power bank safe and not overwhelm it - i think that would mean not drawing too much current? I also cant check how much current is flowing because my multimeter is too cheap and only goes up to 200ma, which the power bank exceeds.

So how would i go about this? What resistor should i use for what wattage should it be rated. And since im a total newb id like to hear your train of thought as to why and how.

Thank you so much.

Discussions

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Downunder35m

2 years ago

I fail to see the point here.
You have a heating wire that is unsuited for the battery apart from the fact that these things usually don't run from batteries to begin with.

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Toga_Dan

2 years ago

if you connect 5.7 times as much wire, with no resistor, it will have the same resistance as now. Then decrease the wire length until wire glows, or battery craps out. I kinda expect the battery to crap out first.

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Toga_Dan

2 years ago

is the red color the important part? Or the amount of heat? Or...