You might try connecting a isolated DC to DC power supply in series with the 12V from the cigaretter lighter socket. Here is on @ mouser electronics. 418-EC9BW-24S33 this is a mouser sk#. I have done similiar before. The input is not isolated so it can be connected in parallel the the 12V from the plug. The output is isolated so the - output is connected to the + of the plug, and the +output of the powersupply and the - of the the ciagarette jack produces the 15V for the load.where can I find retail a 12v convert to 15 volt 5-8 amp cigarette adaptor
in the SE USA??? will a 12 volt run a 15v computer,Toshiba??