Well I've given up on my spiral design, just to much heat and not near enough production. Used 12' each on inner and outer spiral. Have me some SS plates, 22ga. 304, 21/2 X 10". Don't have but 11 of them, that's all the scrap the guy had I got'em from. Think I use an 8 plate design +nnnnnn-, at 14.3 volts that an alternator puts out, I figure that should give close to a 2 volt count down to 0, if I've understood things right. Will let ya know how it turns out when I get it together. I'm slow, so don't hold your breath.