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.
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.
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:
Lithium-polymer batteries have these hard-and-fast rules:
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.
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.
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.
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.
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.
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.
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.
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.
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.
These are layouts known to be run on battery-power with no electricity to the rails (except, perhaps, a section for battery charging).