Help!! Train power from a Car Battery?

A friend of mine is looking to power his N scale train from a 12 volt car battery. Anyone know of some where to buy a control that will allow this?
I made him one using a LM317 voltage regulator, but it's minimum output is 1.2 volts and the friend is looking for something that will go from 0 volts to the full 12 volts of the car battery. Any help is greatly appreciated. Please email responses to: snipped-for-privacy@aol.com Thanks
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LOL!!! Planning on taking your trains with you on a long car trip?
Kent in SD
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On 4/26/04 10:11 PM, in article snipped-for-privacy@mb-m12.aol.com, "Trapshooter870"

Whatever you do, BEWARE THE AMPS! A model train power pack puts out NOWHERE near the amperage a battery will; a battery can easily kill you.
--
Brian Ehni


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A 12 volt automobile battery cannot easily kill you. It CAN under some bizarre circumstances cause death or serious injury but it cannot "easily" kill you. The 220 Volt 60Hz stuff in your breaker box can kill you a whole lot easier and quicker than any 12 volt car battery. The battery can only kill you with the greatest of difficulty. You must help it along quite a bit to achieve such an end. The most probable injury is a minor burn caused from being part of a short circuit.
If you burn your skin off or stab through it then the resistance across the whole body under the skin is only about 500 ohms; even less, if you stab deep enough. So if you take a couple of sharp probes, connect them to a 12 volt car battery, and stab them into your chest, you'll be in a bad way. However, if you do that it is evident that you were already in a bad way to begin with.
Now, while it may be possible (perhaps) to show documented proof of death as a direct result of electrocution from a car battery, it is not something that is a serious problem. Batteries are no more dangerous than the electrolyte inside and the hydrogen they outgass as a result of their function.
Read this: http://engineering-ed.org/computer_repair/documents/ELECTROCUTION.doc
As anybody who's managed to jam his stainless steel watch bracelet between the positive terminal of his car battery and the negative-ground frame will be able to tell you, car batteries can deliver quite a lot of current.
Automotive starter motors operate on 12 volts DC, and can draw hundreds of amps for the (with any luck) brief period when the engine's cranking. Let's assume the battery delivers exactly 12 volts, and exactly 240 amps is being drawn. With that information, you can use Ohm's law to figure out the resistance of the circuit (including the starter motor, its wiring, the internal resistance of the battery, et cetera). R equals 12/240, or only 0.05 ohms. And the circuit power, mostly accounted for by the motor, is 12 times 240 - an imposing 2880 watts.
If 240 amps passes through any significant amount of a human body for any significant period of time, investigators may have to employ DNA analysis to determine who that stuff they found all over the place used to be. You really don't want to make yourself part of a 240 amp circuit. Actually, only about 30 milliamps (0.03 amps) across the human heart has a good chance of stopping it.
Where people go wrong, here, is by thinking that if you disconnect one battery lead in your car, hold the end of that lead in one hand, touch the battery terminal with the other hand, shout "Je ne regrette rien!", and then get a partner in scientific exploration to turn the key, you'll be deader, faster, than someone who's already started his skydive when he discovers that the thing on his back actually contains some chocolate and a sleeping bag.
What will actually happen in the above situation - the car situation, not the skydiving one - is nothing.
The reason for this is that the human body has quite a lot of resistance of its own. If you've got a good contact - the terminals are big enough that the whole palm of each hand can touch them - then the resistance across your body is likely to be between about 2,000 and 50,000 ohms. The thinner and wetter your skin, the lower the resistance will be.
Even if your resistance is only 2000 ohms - which it probably won't be - that's enough to drop the circuit current to about 6mA. You may be able to feel that. You probably won't.
Since your resistance is actually likely to be much higher, the current through your body is likely to be trivially low. And since your body is part of the circuit, the current through the whole circuit will also be trivially low. Hence, the car will not start, and you will not die.
But beware! You can most certainly fry one of those little flea sized N scale locomotives if you do not include some kind of over-current protection such as a fuse or a crowbar curcuit. Fuses are OK and they are cheap. Crowbars are more complicated and expensive but work much quicker. You may still ruin a locomotive even if you pop a fuse. Not really very likely, but the slim possibility does exist.
Don't open the batteries and expose yourself to the electrolyte. It's not a crime, but there's no future in it. You can get nasty acid burns if you're careless or accident-prone.
Don't allow hydrogen gas to accumulate in closed spaces unless you live in Lakehurst New Jersey or your name is Hindenburg. and be sure to vent the inevitable acid vapors that are an integral part of lead-acid batteries. You can buy sealed batteries these days that cannot be opened and that will not spill. That is what I would recommend, but I would still vent them to the outside if possible
NOTE: some of the comments above were C&P from http://www.dansdata.com and some are truly my own. I have messed about with automobile batteries for fifty years and have never been killed by one. Not even injured.
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Froggy@The Pond.com wrote:

Good point. Since I have to transport all my stuff, I never considered using anything other than a sealed battery.
Mike Tennent "IronPenguin"
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While I agree with what you say, there's a LOT glossed over in your last sentence. "Batteries are no more dangerous than the electrolyte inside and the hydrogen they outgas as a result of their function."
Electrical burns are only part of the problem with short circuited car batteries. The internal resistance of the battery will limit the current to some finite value ... in the process it will generate a LOT of heat IN the battery. This can be enough to boil the electrolyte and cause a steam explosion of the battery case. This sprays scalding-hot battery acid and hydrogen gas all over the place, along with plastic and lead 'shrapnel'. NOT good! A secondary hydrogen 'explosion' (see below) is a possibility.
More typically, however, hydrogen is vented during the charging process. If not well ventilated, this can also cause risk of a hydrogen ignition. Unless tightly confined (in a battery 'box' or similar), this is unlikely to result in much of an explosion, but could easily ignite other nearby items. It might also burst the battery case, with results similar to those above.
A car battery can certainly be used for the suggested application. It was common to do so in the 1930's and 1940's. As many have stated, caution and proper use is necessary. A fuse MUST be fitted to the battery, as close as possible to one of the main terminals (probably to the positive one, as the negative is usually considered 'ground'). The main terminals, and ANY wiring ahead of the fuse should be well insulated and protected from accidental contact with (dropped?) metal items. The battery should be in location away from where most persons frequent, and well ventilated (especially during charging). The best ventilation is to OUTDOORS! Perhaps a screened back porch or similar might make a decent location (depending on the climate, but batteries work well to below freezing temperatures).
As a side issue, hydrogen gas vented by the battery can build up in space as large as an entire home. Probably not to dangerous levels, but it can still cause problems. For one thing, it will set off carbon-monoxide detectors (BTDT) ... this can lead to moments of excitement until the problem is correctly analyzed. :-(
Dan Mitchell ========Froggy@The, Pond.com wrote:

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wrote:

Well, yeah, that's right, but I'd already written a dissertation on the subject and my fingers were starting to get raw. So, I wrapped it up.
I have never, ever, never exploded a battery. In fifty years not one. While such is possible, the likelihood of it happening is quite small.
The point is, that it is highly unlikely that a car battery will kill you unless dropped on you from a high altitude. Properly used they pose no threat to your well being. Improperly used.........well..........there is no defense against stupidity, ignorance or carelessness. I would suggest that if one thinks he might be stupid, ignorant or careless that he refrain from doing things that require intelligent thought and planning. Of course I fully realize that such a suggestion is completely wasted.
Of course, in a more perfect world, you would have an 18 Volt 10 Ampere transformer with a 250 Watt capable rectifier on the output. This would feed a regulator circuit built around an LM7812 voltage regulator controlling a 2N3055 pass transistor. Voila! a steady 12 volts with up to 10 Amps if needed. Enough current to run a gargantuan N scale railroad, but not enough to weld trucks and motors to the track.
Never the less, it is entirely possible to use batteries with sufficient safety to run a model railway. It merely requires a bit more thought and planning than using the power company and a transformer.
..............F> Volta Cell, GA.
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such is possible, the likelihood of it happening is quite small.< Two points, years ago I saw my cousin explode a car battery, he was trying to jumper it in front of the house. Lost a good suit, lucky he wore glasses. Second point, mechanics always used to take off all rings. A possible short could really produce a bad burn on the ring finger.
But the real point with model railroading is you must fuse it to the layout. Other wise any short _could_ be exposed to a few hundred amps. That's _hundred_ again.
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Hydrogen, or reverse polarity or both?

They will burn the living snot out of you if you wear metalic objects that can provide a current path. Sometimes they will "bite" you if you are wet and sweaty, however the odds of being fatally injured are too small to be overly concerned.

Absolutely. You can "fatally injure" an N scale locomotive with an unfused auto battery under some conditions
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One dark, rainy night too many years ago to count, I was working as a switchman at Inman Yard in Atlanta. I had to couple to a TOFC car that was wet from the misty rain and also was leaking something. It was steaming as I approached it in the dark confines of the class yard tracks. As I drew closer I could make out the unmistakable odor of sulfuric acid fumes. The lead trailer was facing doors front on the car and one of them was bulged out. A steady trickle of oil of vitriol was dribbling out of the gap at the bottom. The temperature and humidity was stifling that night. The very air was thick with foggy vapor, and now, sulfuric acid fumes. As it had been raining for most of the evening I was quite moist. My clothes, which consisted of a 100% cotton shirt, cotton briefs, cotton denim jeans, cotton socks and leather shoes were likewise considerably moist and limp.
I coupled to the car with the vapors swirling all about and signaled to the engine driver to back out of the track. I caught up on the car ahead of the TOFC flat and rode out on it. The evil fluid continued to seep out.
I dropped off as I passed the north-end conductors shack and walked inside. "Hey Ragman", I called to conductor Wells, "You need to bad-order that first pig in this cut. It's leaking acid from one of the trailers."
I went about my business and in a few minutes we started into another track. shortly thereafter I bent over to throw a switch and the back of my shirt ripped. Minutes later, as I stepped up onto the engine the knee of my jeans tore open, then the other one. In just a few more minutes I was in rags, my clothes literally falling off my body. It had started to rain again and I was dissolving like a sugar cube in a cup of hot tea!
I put on my rain gear and called Ragman. "Hey Rag, you need to call me a relief, I gotta go home." "What's the matter, You sick?" "No, I'm naked"
The acid vapors had literally eaten the damp cotton clothes right off my back. Everyone except me seemed quite amused by the whole incident. The Terminal Super told me to go on home and not wait for a relief, it would be OK, he said.
............F>
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Froggy@The Pond.com wrote:

<snip>
I love it. A good yarn, and about railroads, even.
--
John in Fayetteville
Email address: domain, n4vu.com; username, jsm
  Click to see the full signature.
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Dear Sir,
You are quite right about the rings. That is more a problem when the battery is installed in a car, and especially when the positive terminal is the one closest to the fender wall. Also note that using wrenches with insulated handles keeps you from accidentally causing showers of sparks or welding tools to the car. Don't ask how I know that.
However, you should remember that the amount of current a wire can carry depends on its heat dissipation ability. Well, all right, you can theoretically blow a wire apart with electrostatic force but it's kind of hard to keep it from becoming a gas before you do that. My point is, you will never get those 100 amps to the layout unless you hook the battery up with a cable that can carry 100 amps. If you have a car, look at it, and notice how large the battery to starter cable is, that is if it is old enough that the SOB's didn't hide the battery in some awful corner. If you use a cable like that to hook up your track, yes, you can get 100 amps to the layout, but you'd be a meatball.
What WILL happen, if you hook the battery up with a more reasonable wire, let us say 14 ga, and then lay a Crescent wrench across the rails with power full on, is that something will overheat. It might just turn quickly to smoke, opening the circuit. It might also just get red hot, and set fire to your Styrofoam mountains. Your fuse is simply there to overload before your wiring does. It doesn't matter how many amperes your battery can deliver; one of those ridiculously huge DCC power stations would cause a fire just as nicely if there wasn't any fuse.
I don't know if sealed batteries would be needed. Clamp the battery down and it won't spill. I don't like sealed batteries for cars because I take off the caps and lay a rag over the holes when I am charging them, so any gas will be able to bubble out easily and the battery can't overpressure. I don't care how good the relief valves on sealed batteries are, an open hole is still better.
Cordially yours, Gerard P.
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Agreed. Lead-acid batteries in a car they rarely cause problems other than dying with age. And also agreed that one does NOT want to drop one on one's foot, for various reasons. :-(
I've never exploded a battery either, but I've seen some that HAVE exploded, and it's not pretty.
The big issue is bringing the battery INSIDE, and keeping it in possibly confined and/or poorly ventilated spaces. That is NOT good. In many instances, charging is more dangerous than using the battery, as that's when the most hydrogen is usually released.
And all wiring ahead of the fuse (mandatory) should be protected from accidental contact with metal that may cause 'shorts'. Some kind of ventilated hood or cover over the battery would be desirable.
Dan Mitchell ========Froggy@The, Pond.com wrote:

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http://groups.yahoo.com/group/MRPics http://groups.yahoo.com/group/vintageHO
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Ah, yes.......... One of the hazards of living in the Great White North. We never think of such things down here in Dixie. The last time I saw snow wasn't long enough ago.
............F> Brrrrrr, GA.
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On Tue, 27 Apr 2004 18:36:15 UTC, Froggy@The Pond.com wrote: 2000

--
ernie fisch


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On 4/27/04 1:36 PM, in article snipped-for-privacy@news.west.earthlink.net,

A car battery provides 12 volts DC, pretty low voltage. However, the current it can provide is about 240 amps. The car circuitry (starter motor wiring, inside of battery, connecting wires) has a resistance of about 0.05 Ohms (12 v / 240 amps = 0.05 ohms). The power delivered to the starter motor is 2880 watts ( 12v X 240 amps = 2880 watts). If you grab both terminals of a car battery, the resistance of your skin (2000 ohms or more) will drop the circuit current to 6 milliamps (I = 12/2000 = 0.006 amps), not enough to feel or injure you. Take that same battery and use sharp probes to stick into the chest under the skin to a lower circuit resistance (500 ohms) and now you can be harmed (24 milliamps).
--
Brian Ehni


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Is this the sort of thing that might probably happen to a model railroader using batteries for a power source? Is it possible to accidentally stab yourself in the chest with a pair of sharp probes connected to a freshly charged automobile battery? I must confess, the thought of doing just that has occurred to me many times over the years. What? This is beginning to read lke a Monty Python sketch.
...................F> Dead Parrot, GA
PS: I have always enjoyed sticking my tongue to both terminals of a nine volt transistor battery too.
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Froggy@The, Pond.com wrote:

Never bend over with your back end to the layout!!!!
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On Tue, 27 Apr 2004 18:36:15 UTC, Froggy@The Pond.com wrote: 2000

From my college days I have a recollection that a low current, approximately 10 mA, passing through the chest can affect the diaphragm causing it to stop. So while technically not electrocution (you die of asphyxiation) it can kill. I do not remember the exact numbers (hey, it was more than 50 years ago) but they are in that ballpark.
Since most of us have messed around with 12 volts a lot it is not a common cause of death but it has apparently occurred.
--
ernie fisch


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