Electrical Question

The 12 volts won't damage the motor unless its faulty but you won't be able to connect that to the track without a controller otherwise your trains will be running full speed all the time. So you will need a controller that will take 12 Volts DC input to control your trains. 40 or so years ago it was a common way of doing things but it might be hard to source such a controller now as most have an AC input either 230V straight from the mains or around 16V from a transformer.
More importantly a Car battery holds a lot of energy and can release it quickly if you were to get a short which often happens with derailments. Your rails, stock, derailed Loco and wires connecting could melt in seconds. It is essential that any wires connecting to the battery have a fuse link in them to protect things. For a small 00 layout 2 amp would be a good start point and easily obtainable in car accessory shops with holders to suit.
You could use other types of 12V battery like the sealed Gel batteries used in rechargeable lawnmowers /wheelchairs Radio controlled models etc. Easier to carry around ,tend to have terminals that it is easier to connect smaller wiring to rather than the large type on a car battery. Incidentally if you are buying a new battery specially and really need a large one then get a deep cycle or Leisure battery rather than a car one . They cycle between charge/ discharge better. OTOH and old free car battery will run an OO train a fair while even if a bit tired. Again fusing is essential with any rechargeable battery.
Fairly sure the stumbling block will be the 12 DC input controller. I'd be tempted to buy an inverter to give out 230 AC ,and just use a standard train set up. However some modern controllers might not like the quasi sine wave out put and pure sine wave inverters are more expensive.
Actually something I'd like to know myself .I run a track cleaning train through an old Hammant and Morgan Clipper powered from an Inverter which in turn gets it's power from a solar panel charging the battery .originally for my pond pump it has more than enough for the train as well which runs for hours keeping the track clean as the sun shines. But I haven't risked running the DCC equipment from the Inverter, anyone done that?
G.Harman

I'd also investigate a weather-proof extension accord/cable, of the type used by building contractors, etc. If you don't already have on, install a weather-proof ground-fault protected plug outside the house, and run the cable to your shed, where you can connect it to a standard power-supply/controller. The exterior plug is handy for other things, such as vacuuming the car.
HTH Wolf K.

In message , Roger Thomas writes Hi Roger
Perfectly feasible - just make sure that you use a controller that has short circuit protection so that you do not allow too high a current to flow through the model railway wiring.
Most current hand-held and panel controllers such as those from Gaugemaster or Modelex work fine from 12v DC (mind you I do think you get 13.2v from a car battery) even though they were originally designed for a 16v AC power source. You will also be able to power accessories such as point motors or lighting from the battery.
One thing to be careful about - if you intend to use more than one controller on a layout that uses common return wiring, then you will need a separate battery for each controller. This can be avoided by wiring each track section completely separately and using double-pole switches for cab-control.
You have not said whether you are using analogue or DCC control systems. Most DCC systems use a DC power input so the battery should be OK as a power source for a DCC system - just check the specifications to be sure.
If you need more help - ask!
Regards.

Yes, but fit some appropriately rated fuses or circuit breakers immediately after the battery and before it goes anywhere else. A car battery will deliver a huge current if it gets a short circuit, hundreds of Amps. Enough to burn straight through any moderate diameter wire. An alarm battery will give slightly less, but still enough to do damage.
A chap I knew (now died a few years ago) used to run his layout on a handful of AA batteries. Simple two-transistor speed controllers with centre-off direction switch. He'd get a whole day out of the batteries. AA rechargeables would also work, though note that quite a few types deliver nearer 1.2v than 1.5v, so you may need 10 for a full 12v, not the eight disposable batteries.
Many DC controllers are OK on pure DC, though not all (some need the ripple from 50hz AC to work some of their tricks). Most DCC systems need DC input of appropriate voltage.
- Nigel

That's definitely possible. Fuses are essential, a car battery will supply 100s of Amps for a short period and will soon let the smoke out of your layout in the event of a fault.
Virtually any sort. You need enough in series to get the voltage up, and high enough capacity for an typical operating session. You can get 9Ah NiMH but they will cost you more than a car battery.
Check whether the battery type you choose can be left in a discharged state or require constant trickle charging (not so convenient if you have no other power source).
MBQ

Assuming you have a controller which will work with 12 volt DC input, then, instead of using an actual car battery, you might consider using one to the 'powerpack' devices as sold for starting cars when the car battery is flat. Some models have 12 volt 'car cigarette lighter' type power sockets (e.g. If you had one of those power packs, and rigged your controller to a car cigarette lighter type plug, it would be simple to connect and disconnect the battery pack, which would be clean and easy to carry indoors for a recharge, when required. And you could start your car in emergency, too ...
Alternatively, some power packs also feature 230 volt AC inverters, e.g. There are plenty to choose from.