model lighting- electronics question!

[Mark B]

I have a diorama that with 4 grain of wheat bulbs for lighting- currently they are all wired to in parallel and running to a model railroad transformer (wall power, 12v output).  Is there a way I can connect these to battery power?  I have a show to display at where I won't have access to electricity.  

 

Any help is appreciated!

 

Mark

[peteski]

You could replace the 12V wall-wart with a standard 9V transistor radio battery. (does anybody still call these batteries "transistor radio batteries"?).   But  the bulbs will glow a bit dimmer (9V is less than 12V) and the battery has a fairly small capacity so it won't last very long. How long? I can't tell without knowing how much current the bulbs would be consuming at 9V.

Another possibility woudl be to get a battery holder which holds 8 AA cells. That gives 12V and the capacity of AA batteries is much greated than the 9V battery so that woudl give you full brightness for much longer time than when using a 9V battery.

You could also get yourself a surplus 12V rechargeable gel-cell lead-acid battery.  Something like this one .  It would probably power your lights for couple of days on a single charge.  But you need to have a charger for it (standard car battery charger will work well, or get a dedicated charged like this ).  But you need to be careful with this type of battery because if you accidentally short it out it can supply enough current to heat up the shorting piece of wire (possibly to the point of melting or burning the insulation).

Another alternative is to replace the light bulbs with white-color LEDs (light Emitting Diodes). They are bright, don't heat up, and use very little current. Those you could easily power from that 9V battery for hours.  But they are a bit more complex to hook up properly. If you do this Google search you'll find lots of helpful information on how to hook up LED

Edited September 6, 2016 by peteski

[Ace-Garageguy]

Just one minor note on the above comment: LEDs wire up just like grain-of-wheat bulbs. Wiring them parallel makes them all the same brightness. If you buy the pre-wired units for the correct voltage, they come with red and black pigtails and hook up identically to your incandescents.

As Pete says, they are bright. They also come in a wide variety of colors and configurations, and can open your model lighting to a whole new world of possibilities.

I routinely use them in 12V applications where I don't need dimmability, want instant "on", with very little heat.

[BigTallDad]

You could also use two 6 volt lantern batteries wired in series...kinda bulky, but it'll work.

I have a '55 Chevy with headlights (hi/low beam), parking lights, tail lights, brake lights, and turn signals, all using grain of wheat bulbs and a railroad crossing flasher for the turn signals. I use a 12 volt adapter that plugs into the wall, but I can also use the lantern batteries if I enter the model in a contest.