This had me confused as well, John. But what was happening in my case was that although I had the velocity dial cranked all the way to full speed, at the time I pulled the batteries out of my CAB-2, it was in the midst of steadily spitting out absolute speed commands which were building their way up to 199. But at that point, they would have been at, say, 100 or so. So there would have been no reason for the loco to continue accelerating because it never saw a command that said go to 199. Even though I cranked the throttle all the way up, the CAB-2 was issuing much lower speed commands and gradually building up. So it makes sense that it just held steady when I pulled the batteries.
It was only after I set momentum and then injected an "absolute speed 199" into the serial port that I saw the speed gradually increase -- whether the CAB-2 was powered on or not. Because in that case, the loco was managing momentum and knew it needed to get all the way to 199.
That makes sense now that we think about it, doesn't it?
