Back in High School I was fortunate to find a beautiful Aristocraft U25B with Union Pacific livery at a garage sale. The seller only wanted $80 and it came with a few cars and track, I couldn’t believe my luck!

That was about 10 years ago. I’ve since been through college, lived on multiple couches, gotten my first job, found the girl of my dreams, the list goes on! This year while visiting the San Diego county fair I re-ignited my passion for model trains. I’ve found out there is a very nice gentleman (Steve) who lives nearby with a garden railroad in his yard, the Gopher Canyon Line. He runs ‘dead-rail’ meaning there is no electricity on the track. This is a great idea for model railroading because it means not having to worry about bad connectivity with the rails for the electricity to run the motor(s) in the train engine. Instead, batteries are built into the engine or a trailing car and power the locomotive, brilliant!

However, this is bad news for my Union Pacific U25B. This old train powers the motors directly from the track voltage. As I said, Steve’s Gopher Canyon Line has no voltage on the track so I need to convert this locomotive to use battery power.

Brainstorming

I am an engineer with experience in microcontrollers (Arduino mostly), remote control electronics (model airplanes, drones, etc.), and I have a fiery passion for trains! This sounds like a potentially awesome combination, lets get started.

Batteries

Lithium-Ion is the way to go. Higher voltage than most other chemistries (3.7v nominal), larger capacity, and flatter voltage curves mean I’ll get a lot of power per mass.

I’ll be going with 18650 cells, mainly because I’ve never worked with them before. I used flat-pack cells a lot in RC planes and drones and while there are lots of packs available in varying dimensions and chemistries, the swelling that occurs with these packs is the main reason I don’t want to use them. If I design a battery compartment with x width and the pack swells up to x+y width over time, I risk damaging the locomotive and maybe even a fire hazard.

So yea, 18650 cells and hopefully a charging circuit. More on the charger now.

Charging said batteries

This is where my over-engineering mentality takes over. See, I want to run my train on tracks that don’t have any electricity in them. Therefore I’ll obviously have to charge my train while its not on the tracks. But what if I want to run on a layout that does have electricity on the rails? Wouldn’t it be great if the train kept the batteries charged if the rails had power available? I think so.

Remote Control

This is going to be a large part of the project. I want to be able to control the train wirelessly, from my phone or from a remote control I’m not sure yet. Bluetooth, WiFi, or some other wireless communication? I’m not sure what I’ll be doing for remote control just yet.

Extensions & Addons

Extras I’m considering are an external battery car, lights, and sound.

The U25B already has three light bulbs inside but they are old incandescent bulbs and only one color. I would like to have multi-color LEDs that change color depending on the direction of travel. Forward facing headlights that change to red tail lights.

Aristocraft used to manufacturer a sound unit that was available as an add-on installed in the fuel tank on the underside of the locomotive. From what I’ve heard the sound is pretty realistic but I think they are fairly expensive units and I wouldn’t have any development access to change the sounds myself. Never-the-less I would love to have good sound for the locomotive.

Finally, an external battery car would mean extended battery capacity for long run days. From talking to Steve and a few of the guys at one of his meet-ups, I don’t need a lot of battery capacity to run for a full day, so this really isn’t a top priority. Still, it would be pretty cool to have the extra capacity available to me if I want it.

Stay tuned!