Why use the battery charger? Just use the battery charger as it is intended: To charge the battery and use the battery to heat the wire. Connect the minus to the battery/wire and use the plus of the battery and touch the other side of the wire for 2 to 3 short ticks and problem is solved. Worked even with a 25Ah battery, but we now use a 150Ah battery we have in the workshop anyway. Oh, and do not forget to include a 20Amp fuse in the + line so you are safe, just in case there is a problem somewhere.