We have the Tomix track cleaning cars. we've been having to switch them on and off manually as the train runs. What was needed was a DCC decoder, but done how? There is actually a "plug and play" PCB upgrade available that takes a 6 pin plug-in decoder, but it didn't look too hard by hand.
The motor has a true stall current on about 1.2A, BUT the body of the cleaner also has a self-resetting 0.25A fuse. So the continuous current shouldn't exceed that value.
A locomotive decoder with the same DCC number as its pulling locomotive was one option. With speed profiles, I could make it ramp the cleaner motor speed from nothing to full speed as soom as the loco moves. But in the cupboard I had an accessory-only decoder without a home. It's a Lenz LF100XF with 4 functions; two are rated at 300mA which is probably high enough.
Not a difficult install: I've actually put the decoder in the dust bay, taking up tiny space and not obstructing the airflow. It runs on Function1; give it the same DCC address as the hauling loco, then press F1 when the train starts up.
What's not so simple is having Traincontroller do that automatically when the train starts. You can make that happen on a particular schedule, but not on any action of the loco. Watch this space!