Try'd my small 9 plate unit today, warmed it up for about 30 min and swapped polarity to see if one made more or not, at first it was -nnn+nnn- then +nnn-nnn+ .... then checked voltage "battery was at 12.3v" and then checked what the current draw was..
http://img.photobucket.com/albums/v6...h_3ccc42ff.jpg