35w to 55w

hi,

you'll need to read up a bit on Ohm's law..but here's the basics

20 w @ 14 v = 10 ohms (close enough),

so you need to add a 10 ohm resistor in parallel with the input side of your ballasts.

the power value of the resistor must be taken into consideration also.  a 20 w resistor may well work but for a safety factor, you'd increase the value to 50 w.

20 w is a significant amount of power / heat to dissipate (think about a small soldering iron), so you'll also need a heat sink to remove the heat into the air.  if you can mount the resistors/ heat sinks where air is flowing across them, it would definitely be desirable

hope this helps

mark