laserman Have tested it today with 2X12VDC 12Ah lead-gel batteries in serie (24 VDC)In only a few seconds it made the middle piece of a teaspoon glowing.Because the coppercoil (madev of coppertube)) became hot, it is advisable to flow water through it to cool the coil itselve , that helps to lower the resistance of the coil itselve and reduce energy- loss of the system.A massive coil would warm up slower but the skineffect makes that the impedance will not be much lower at 150KHz.

laserman Have one wich makes sparks of 20CM and that one produces 300KV (uses 30VDC 20A) The writer of this review must have ment 10-20mm

laserman Tried out the max arc with only one 18650. This was a remarkable 3.4 CM (all 3 the generators performed about the same.When used 6VDC (SHORT) I have seen others with these generators making arcs of 4.5-5.0 CM. That means that the max voltage must be estimated up to 50KV and a loud bang. Used in that configuration it must be considered as aperfect basis to build a nasty taser.That means also that unsafe operation can shock you knock out in a few seconds. I suggest not to test this out.!!