be very carefull. I have a second hand NG3 and it's configured to 120 volt PB. the company in San fran is very tight lipped about mods. their only answer is send it to us for a credit and refit. Cost?? my unit workes great on my PB pack at 230 volts input which is a little bit limiting, as I would also like the 110 volt option, when I wrote to them for a conversion they told me that they were hard wired single input/output only i.e. 230 volt or 110 volt only. but I would like to reconfigure it too I think they are spacifically designed and ordered from the factory. now my unit chagres my 120 volt pack @ 22 amps to 144 volts and 18 amps to 165 volts WONDERFULLY, very little gassing and a perfect PB balancing charge still it is a little limited. My unit still has the factory tape seals and I'm loath to break them but it might come down to It, as Im considering upping my pack to 144 volts PB. I did come across an article here where a member had broke the seals and adjusted his unit, If I do that I will report here. good luck