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Battery Power

The purpose of this page is cover battery-powered engines in S-scale. Battery-powered locomotives, also known as "Dead Rail", is not an entirely new concept. If you are familiar with G-gauge (garden railroading), you will have likely already seen some of those engines being run with internal batteries. It is a key bit of technology for that gauge, because rails out in the open get dirty very easily and so electrical rail-to-wheel contact may get interrupted quite often.

Does It Fit?


example installation into a Railmaster Exports RS-1; copyright © Peter Vanvliet; used by permission

Thanks to the advent of cell phones, and the continuous miniaturization of those phones, we now have very small, but powerful, lithium-polymer batteries. Nearly everyone has a cell phone, or has at least seen one operate. Battery-powered engines in G-gauge were practical because there is quite a bit of space inside those locomotives to house the rather large batteries. However, when you look at the interiors of HO-, S-, or O-scale engines, there isn't much space available for large batteries. The cell-phone-sized batteries are now small enough to where they can fit in locomotives for these indoor scales.

With the exception of systems for G-gauge, most battery-powered systems are designed to fit inside HO-scale locomotives. Since S-scale engines are slightly bigger than HO-scale ones, and since modern S-scale locomotives are or can be powered by the same motors that are used in HO-scale, it makes powering S-scale engines with batteries very much a reality.

The photo of an example S-scale installation, above right, shows the battery in the locomotive's shell (upper right), and the electronics board above the rear truck (lower left). The orange wires lead to an on/off reed switch (triggered via an external magnet) to turn the system on or off.

Why Go With Batteries?

Having a battery within your locomotive means that it gets a steady stream of power regardless of whether or not the wheels can make electrical contact with the rails. This actually takes us one step closer to modeling the prototype, as real locomotives carry their source of fuel with them as well.

We have all heard engines with built-in sound suddenly go quiet, and then do their entire start-up sound routine again when the locomotive's wheels temporarily lose contact with the rails. Before sound in engines was popular, you'd see the engine stammer and then continue to run, which was annoying but easily ignored. However, with sound, this momentary interruption is very noticeable. Some companies have come up with a solution by incorporating the new "super capacitor" in their engines or DCC systems (a.k.a. "Keep Alive"), which provides just enough power from the capacitor to the locomotive when it detects a temporary power outage. You can think of a capacitor as a very short-term battery. You don't have to go full battery power, if that is all you want to solve.

However, having a full-time battery on board your locomotive also offers these potential benefits:

  • the frogs of turnouts do not have to be powered, so no concern for polarity switching there.
  • turn-back loops do not need to have their polarity switched each time a train enters.
  • wyes (triangular junctions) are difficult to wire properly due their polarity switching between the three routes.
  • turntables also have polarity switching issues, when the table can turn 360°.
  • polarity or grounding issues can result between DCC districts.
  • a short-circuit on the layout will have no impact on your engine.
  • when the club's layout experiences electrical issues, your engine keeps running.
  • you can model things previously not possible (see Dave Heine's article near the bottom of this page).

Are Lithium-polymer Batteries Safe?


example battery; copyright © Peter Vanvliet; used by permission

Lithium-polymer batteries have these hard-and-fast rules:

  • do not overcharge them.
  • do not drain them below their minimum.
  • do not puncture their jacket.

The media likes to blow things out of proportion to draw your attention. So, in the past there have been headlines such as "Such-n-so's cell phone battery exploded!". Since lithium-polymer batteries are in use in literally billions of cell phones now, we have a pretty good grip on how to handle them safely. Lithium-polymer batteries are packed in a sealed "bag" that keeps all the nasty stuff inside. What actually happens when such a battery "explodes", is that the internals of the battery's "bag" expand and it gets very hot. The odds of the seal actually breaking is extremely small. The odds of the broken seal then leading to a subsequent fire are even smaller still. This can happen only when a lithium-polymer battery is overcharged. That is why it is extremely important to use the manufacturer's recommended charger when you are charging your cell phone (or your S-scale locomotive). However, due to past failures, most lithium-polymer batteries nowadays come with a built-in circuit board that stops the charging should an overcharge scenario occur.

Nonetheless, there is inherently a risk in charging your cell phone and your S-scale locomotive's internal battery. In practical terms, when you equip your locomotive with an internal battery, and the battery stays inside the locomotive when it is charging, keep a close eye on it during the charging phase. At least for the first few times. One advantage of lithium-polymer batteries is that they don't have a "memory". Older technologies required that you fully discharge the battery and fully re-charge it again. If you didn't fully discharge the battery, it would no longer allow its maximum charge-holding ability. The lithium-polymer battery can be charged or discharged as you please, with no problem. So, you can unplug the charging when you need to step away from it for a while, and then resume later on. Once you gain confidence in your new system, you can let it charge unsupervised.

Another word of caution. If you buy a battery-power system, be sure to buy batteries from that manufacturer, or the exact battery that they recommend. You can go on the Internet and find cheaper batteries, but they may not have the overcharge protection built in. They may also not have the capacities that the manufacturer's batteries have. The cheaper ones could be more dangerous to use. The couple of dollars saved is not worth the aggravation, the damage, or the loss that a bad battery could generate.

The other limitation that a lithium-polymer battery has is when it is drained below its minimum. When this happens, the battery will no longer ever hold a charge again. It won't lead to an "explosion", but it will make the battery useless, and it will need to be replaced. Some of the battery-powered train control systems on the market today will have electronics built-in to guard against that. When that scenario is encountered, they will instantly cut off the power from that battery, so your engine will simply stop in its tracks (pun intended?). You can then re-charge the battery as normal.

How Does It Work?


example non-sound S-CAB set-up with NCE DCC decoder; copyright © Peter Vanvliet; used by permission

There is a circuit board in the engine that receives power from the lithium-polymer battery in the engine. This board converts the (typical) 3.7 volts that these batteries produce to the around 12 volts that our locomotives need.

On some systems this circuit board also manages the charging of the battery. The board then routes the battery power to the engine's control system, such as a DCC decoder, for example. The control system is the one that actually receives the instructions from the throttle that you control. The control system is responsible for sending a voltage to the motor (to control its speed and direction), and may also control the onboard lights and/or sound.

So, the internal battery simply replaces the purpose of powered rails on your layout. Some systems support re-charging the internal lithium-polymer battery via the wheels, some require an external charger, and some systems require you to remove the battery for it to be charged. There are plusses and minuses to each of these solutions. Let's look at those.

Charging Via the Rails

The big plus with this approach is that you do not need to touch the engine to charge the internal battery. You can have a section of your layout (or all of your layout, if you have an existing system in place already) that has some power applied to the rail (can be AC, DC, or DCC). Assuming that the rails of that section are clean, and that the wheels of your locomotive are clean, as soon as the engine enters that powered section of track, the internal system will start to charge the batteries.

The minus of this approach is that you have to have a section of track that is powered, and it requires an internal circuit board that can manage the battery's state. If your battery is completely drained, you will have to wait some time before the engine can be run again. In the extremely unlikely scenario of your battery being overcharged, the battery's expansion could cause internal damage to the locomotive.

Charging Via an External Charger

This may eliminate the need for some internal space that the charging system's electronics needs. Also, you can have absolutely no power to any portion of your layout at all. You also do not need to worry about the cleanliness of your rail and your locomotive's wheels, nor would you have to have the wheel power pick-ups be there and be functional.

The biggest minus of this solution is that you have to deal with the plug. It could be hidden in a hatch that you manually open, or it would have to dangle out of the engine somewhere. This may be unsightly. Also, you will need to handle your locomotive a bit. If your battery is completely drained, you will have to wait some time before it can be run again. In the extremely unlikely scenario of your battery being overcharged, the battery's expansion could cause internal damage to the locomotive.

Charging By Removal

This may eliminate the need for any kind of charging support electronics inside the engine (i.e. less circuit boards in the engine). Also, you can have absolutely no power to any portion of your layout at all. You also do not need to worry about the cleanliness of your rail and your locomotive's wheels, nor would you have to have the wheel power pick-ups be there and be functional. You can remove the battery and replace it with a fully-charged one, and have the locomotive up and running again quickly. In the extremely unlikely scenario of your battery being overcharged, the damage will not affect your locomotive, as the charging will likely take place elsewhere.

The biggest minus of this solution is that you have to really handle your locomotive, maybe even remove its shell. When a plug can be installed to quickly disconnect the battery, it may still take some time to open it all up. G-gauge locomotives that use battery power use this approach, but they generally have a large hatch at the top of the locomotive that provides full access to the battery, but that may be harder to create in our indoor models.

I Want More Information!

If you are really interested in powering your locomotive with an internal battery, be sure to visit the webmaster's personal web site for a full treatise on the technology.

Available Systems

Some systems use a radio-frequency throttle and some require a smartphone to control the engine. Either way, all systems are wireless, so you can walk with your train. Below is a listing of known systems that can be used inside of S-scale locomotives to convert them to run on battery power. If you are interested in investing in this technology, be sure to study the manufacturer's documentation, their restrictions and limitations, and the additional equipment necessary to run trains using their system. Also, there are a number of professional installers who will install the system you want into your locomotive for a fee, if you don't want to tackle it yourself. If you have done a couple of DCC decoder installations yourself (especially non-plug-n-play ones), you might be able to install a battery-power system yourself. The hardest part is not the electronics, but the creative solution it takes to fit the various components into your engine.

  • Blue Rail Trains
    BlueRail used to offer their own system, but they are now purely a software-based solution for other companies' hardware solutions. Currently, they are working with SoundTraxx for their "Blunami" decoder, and with Tam Valley Depot for their "BlueRailDCC by Tam Valley" solution. Their software runs on Apple- and Android-based mobile devices, and so requires the download and installation of the appropriate app on those devices. The mobile device then becomes the user interface with which you control your engine. This uses Bluetooth communication. Bluetooth is a short-range wireless technology implemented in nearly all mobile devices (think of it as a very limited-range radio-frequency communication system).
  • CVP Products
    CVP Products is a Texas-based company that makes the microAirWire system, which can output up to 1.5 amps (5A surge). All their decoders are DCC-compliant. The company has two physical throttles available, the T6000 PRO-OPS (with full programmer) and the T2300 OPS (non-programming). Together, they provide radio-frequency-based communication between the throttle and the microAirWire board that is installed in the engine. The modeler has to provide the internal battery and battery-charging system, if battery-power is desired. Otherwise, power can come from conventional rail-based connectivity.
  • LocoFi
    LocoFi has a WiFi-based solution. A controller communicates via your home's or club's WiFi router, and the WiFi router communicates those commands to their LocoFi Module, which is a circuit board to be installed in each locomotive, which supports motor control, lights control, and sound.
  • Micro Flier Radio
    Micro Flier Radio makes R/C components for very small flying model airplanes. They offer the components necessary to remote-control an engine running on battery power. Receiver circuit boards are available for 1.2A, 1.5A, 2A, 3A, and 4A uses. Note that the company's components will require electronics knowledge to properly install and use them, but some S-scale modelers have used it with some of the S-CAB components to build a complete solution.
  • ProMiniAir
    ProMiniAir offers a transmitter and receiver. These can work with CVP's Airwire, S-CAB, Tam Valley Depot, and Gwire, and the transmitter can connect to any DCC throttle's track output, or use a smartphone throttle app or JMRI. Their focus is being able to integrate into an existing DCC system that you may already have installed. They also have their own Arduino-based DCC command station.
  • Protocab
    This company made a hardware throttle that looked like a real locomotive's control system. However, the web site is essentially gone, and their last update indicated that they have halted their production due to the permanent unavailability of some key electronic components that they were using. The company had recently changed their name to "Acc+Ess Protocab". As of July 2024, the company is only focusing on supporting existing customers.
  • Ring Engineering
    Ring Engineering makes their RailPro, two-way radio-frequency control, system that offer an intuitive throttle and can be made to support battery power. Several S-scale modelers are using this system.
  • S-CAB
    If you are looking for a complete out-of-the-box battery-powered system, S-CAB should be near the top of your list. The company's products are geared toward those who have an existing DC-based layout, or those who are starting a new layout. They sell a dedicated radio-frequency-based throttle, and the necessary components to install into an engine to control it (via third-party DCC decoders, sound and non-sound) and an internal battery that can be, optionally, charged via the power pickup of an engine's wheels.
  • SoundTraxx
    SoundTraxx manufactures and sells their Blunami decoder. This decoder is essentially a Tsunami-based DCC decoder with sound, but with the added ability to receive control signals from a mobile device. It uses Bluetooth short-range wireless communication to accomplish this. It can be powered by a battery inside the locomotive, but the modeler has to implement that (or send the engine to a professional installer).
  • Tam Valley Depot
    Tam Valley Depot offers the BlueRailDCC by Tam Valley solution, which uses the BlueRail Trains system. This is controlled via a mobile device (as the throttle), and the board that they sell connects either directly with the internals of the engine (for simple DC mode and basic features), or it can be wired to a third-party DCC decoder (e.g. the SoundTraxx Tsunami sound decoder). The power source for this board can be AC, DC, DCC, or internal battery. The modeler has to implement the battery solution, if that is the desired plan.
  • Wifitrax
    Wifitrax is an Australian company that provides a system by which you can control an engine through Wi-Fi-enabled cellphones or tablets. They offer a module, the WDMI-32, that you install between a battery and a DCC decoder (both of your choice and you must install and provide these). Once installed, any WiFi-enabled device can run an app that can detect and run that engine. They also offer components that allow WiFi-based control over switch machines, something that none of the other companies listed above offer.

If you are familiar and comfortable with electronics, and you like to tinker, you can combine several components of any of the above-mentioned companies to build your own custom solution.

Model Rectifier Corp (MRC) produces their Loco-Genie system, which offers a remote control with which to run your engine. While the MRC system does not directly make available a way to power their system with internal batteries, several S-scale modelers have installed it and added the Neil Stanton Battery Power Supply (BPS) board. This board will handle the charging, on/off state, and the powering of the system's components. A little bit of electronics work is involved.

Example Installations

A good number of S-scale modelers have taken to the battery-powered solution, and have integrated it into their layout. Some have adopted the technology when they started their new layout from scratch, some have converted from an existing DC or DCC system over to battery-power only, and some have simply installed it in one or a couple of engines. The important thing to remember about battery-powered systems is that, if you already have an existing layout with an existing system, you do not need to get rid of that at all. It is not a whole-sale change like going from DC to DCC was, for example. The battery-powered solution can peacefully co-exist with your existing AC, DC, or DCC layout. You can convert just your trouble engines (0-4-0 for example), or convert more engines as time and money allow. As a matter of fact, if you take your engine to your friend's layout (or local S-scale club), and you convert your engine to battery power, you can be completely independent of whatever system your friend's or club's layout is currently using. If your engine supports re-charging via the rails, then your engine's battery will be charging while it is running, thereby extending your total run time by a large margin.

"Dead Rail" Layouts

These are layouts known to be run on battery-power with no electricity to the rails (except, perhaps, a section for battery charging).

Articles

Additional Resources

  • "The S-CAB System", 2013 NASG Convention clinic by Peter Vanvliet offers a good introduction into battery power and S-CAB specifically (view it here)
  • "News from the North", NASG Dispatch March 2018: article by Jim Martin having had his S-Helper Service SW9 converted to BlueRail Trains with battery power (read it here)
  • "Train Control and Battery Power", NASG Dispatch July 2018: article by Peter Vanvliet introducing "dead rail" and battery power (read it here)
  • "Battery Power", NASG Dispatch January 2019: article by Brian Walsh on how he got into battery power and demonstrating his first conversion (SHS NW2) (read it here)
  • "A Battery-powered Caboose", S Scale Resource April 2019: article by Peter Vanvliet about how to power the lights of a caboose (or passenger car) on a "dead rail" layout (read it here)
  • "Simple Battery Turnout Control", NASG Dispatch July 2019: article by Jim Martin about how to throw a turnout using a 9V battery (read it here)
  • "Better Off Dead Rail", 2019 NASG Convention clinic by Darby Marriott offers a good introduction into various battery-powered solutions (view it here)
  • lithium-ion vs. lithium-polymer
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