Video with simple proof-of-simplicity example
*sorry i am using a different video, but you get the point probably*
In the video, just 3.7 V’s was applied with (measured) 2.5A current. The smaller the wire, the higher the current, so don’t get the wire too small.
Sizing it up
[caption id="attachment_1304" align="aligncenter" width="300" caption="A 50cm hotwire!"][/caption]
What you see in the image above, is a hotwire running over a steel thingy i had lieing around. It’s a good 50cm, ideal for cutting anything. I just wired it up directly to two LiPo’s (in series) having a total of 8V. LiPo’s have a pretty low internal resistance, so that will go fine, as long as you have the nichrome wire in place. I have nichrome wire that has 7 ohms per meter. I can not suggest you get a lower resistance than that, or the lipo might blow up. Anyway, i loved it, it cuts through EPS like butter.
Applying it for nylon cord cutdown
That’s easy. Just connect it to a simple relais (or some strong minimum 2A MOSFET/transistors). Just let any processor flick a switch and the nichrome wire will be glowing hot, cutting through anything nonmetallic (until it cuts itself).
Disclaimer: i advise you not to try this at home.