No heat from nichrome wire. I have tried various experiments on YouTube regarding foam cutters using nichrome wire or steel wire with 9V batteries with an on/off switch or no on/off switch.

When the steel wire didn't work, I tried using N80 30AWG nichrome wire. I connected the wires from the battery directly to the nichrome wire and no heat at all. I even tried connecting two 9V batteries. I only have a basic understanding of electricity but the simple DIY foam cutters on YouTube do not seem to be much of a challenge to create. Appreciate any help or other tests I can perform to confirm I am getting heat. Oh and the batteries are fully charged.

  • \$\begingroup\$ Dead battery, I would say. \$\endgroup\$
    – Eugene Sh.
    Feb 13 '19 at 15:45
  • \$\begingroup\$ Or you didn't properly strip the insulation on some wires. \$\endgroup\$
    – Hearth
    Feb 13 '19 at 15:46
  • \$\begingroup\$ How long a wire? Did your batteries get hot? \$\endgroup\$
    – Oldfart
    Feb 13 '19 at 15:46
  • \$\begingroup\$ 9V battery is quite useless in this application. Try calculating the voltage needed. \$\endgroup\$ Feb 13 '19 at 15:47
  • \$\begingroup\$ Have you measured the resistance of your nichrome wire? \$\endgroup\$
    – JYelton
    Feb 13 '19 at 15:48

According to my quick ca. 2000 test, a fresh Duracell 9V battery can briefly supply 5A of output current, so a couple ohms source resistance. Zinc-carbon batteries will not supply anything like that. Do not attempt with NiCd batteries, explosion can result.

That's more that sufficient to burn your fingers with even a small (eg. 10-20mm) length of wire. This set of tables should give some basic idea of how much current is required for a given free-air temperature.

It's around 7 ohms per foot (30cm) so the length needs to be perhaps in the 4" range to get up to >500°C.


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