The Christmas thread about having a train around your Christmas tree got me thinking. Could you convert an HO scale DC locomotive to battery powered. Larger scales use battery power. Putting a battery in a HO scale locomotive would result in a very short run time, since the battery would have to be small.
We want a bigger battery so it would be out side of the locomotive. A great place would be in the model behind it. Either a dummy locomotive or piece of rolling stock. The dummy locomotive would look more realistic, especially if it is a slug. You can hide the wires in plain sight as MU and power cables.
Looking for something more unique? You can model a Natural gas test locomotive. Hide the batteries in the fuel tender, and hide the wire in the fuel lines.
I have just read your post (been on a holiday). The 45mm guage ‘boys’ have been using R/C equipment for some time now, and I remembered an article (took a while to ‘dig it up’) from April 2010 in AMRM (Australian Model Railway Magazine). Neil Stanton was developing on-board power using mobile phone batteries to drive ‘Spud’ trucks, and I think he was aiming to control it with R/C.
People who don’t follow the battery trade may not know it but new types are on the way that last 4 times as long and recharge in less than 30 min. Lipos as they are will give you a 6 hour run time and the decoder is less than 1/2" x 1/2". All this is comminly called dead rail.
