I haven't had a chance to actually measure the current pulled by the OI. But I know that when we tried to use a 1 Amp supply (over the years, we have lost four of our OI and RC power supplies, so we now have a lot of experience with replacements), the OI appeared to work just fine. However, the radio link with the robot was absolute crap if we were more than 10 feet away. Moving up to a 1200 mA supply extended the range to about 15 feet, but we still had lots of drop-outs. Somewhere between there and 1500 mA you cross a threshold, and at 1500 mA it works just fine.
What I learned from all this is that I want to sit down with someone who really understands RF systems, and see if we can cobble together a really cool signal amplifier that we can run off my 100 Amp supply. Then we will sit back and drive our FIRST robot from the next state...
-dave