8885 is just on-off.
The train controller is proportional, but useless for most things because it doesn’t return to centre and because of the way it uses the IR protocol, “centre” keeps moving. Whenever you turn the wheel, it sends a “go a bit faster” or “go a bit slower” message rather than “go at speed X”. This means that if the receiver misses a message, the zero point wanders around. So even if you were to figure out a way to make the dials spring loaded, it’d still be useless.
I’m pretty sure that I read that the receivers support a “go at speed X” message, so it’s a shame that Lego never released a controller that used it.
The tracked racer works really well with proportional control because you can choose whether to do a wheelie or not, and by putting one control forward and one almost all the way back you can do a really fast wheelie spin (well, it amused father and son for longer than it should have done)
I didn’t know the battery boxes had a current limitation. I thought it was all in the receivers.