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.
I suppose it is not beyond the realm of theoretical possibility for a pig to somehow fly, or at least become propelled through the air in a semblance of flying. However, I shan't wait to see.
Find out how many people have ever been killed from electrocution by automobile batteries and then divide that by the number of people on the planet. Then take that number and multiply it by the percentage of the population that are model railroaders There's your odds.
First, you have to find ~one~ that is documented somewhere other than Snopes.
I am not trying to give Bryan ( or anyone else) a hard time here, I just think that while it might theoretecally possible to be seriously injured by the electrical energy of an auto battery, it is not a practical concern.
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
Well, lets see, .003 amps would be 3/1000 of an amp or 3,000 microamps or 3 milliamps and .03 amps would be 30/1000 of an amp or 30,000 microamps or 30 milliamps. Check me again on that and make sure I have it right. I think 30 milliamps = 0.03 amps. I'll look at it again in the morning
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.
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.
Yes and no. Amps and volts. It takes some of BOTH. You can't get a current through a resistance without SOME voltage being present. It's just Ohm's Law. Specify any two of the variables, and the third is determined.
I can usually FEEL the current through my body from contact with the 12 VDC on a model railroad. It's easier to feel with most skin. Such contact is NOT dangerous under ANY normal condition. It takes substantial voltage, almost always more than 40 volts, to get a dangerous current to flow through the human body. It's hard to get a really serious shock from even 110 VAC. Uncomfortable, sure, but rarely fatal. Electricians COMMONLY work on live 110 VAC circuits. They've learned HOW to do it relative safety. Some persons do succeed in killing themselves with 110 VAC, however, so don't take it for granted.
220 VAC is **BAD** news. That's just about the right voltage to get a fatal current through the upper body EASILY ... *NOT* good. 220 VAC circuits are about the worst electrical danger the common person is likely to encounter.
Strangely, even higher voltages often cause LESS serious injury. They'll burn you, and maybe blow you clear across the room, but MANY people have survived such shocks. Many even survive being hit by lightning, though rarely without serious injury.
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.
Yes, you can use a battery but your friend will run into the problems of maintaining a battery for a long period of time - batteries tend to last only a few years before going bad. The LM317 circuit needs to be setup as a variable voltage regulator rather than a 1.2V regulator. This is done by two resistors to bias the control terminal up from ground. Better is to use something else in the way of a throttle with a better pass transistor for the output. You can build a power opamp that will be able to control the output voltage a lot better than the 317 for the high voltage end. MOSFETs are available that have very low resistances that can be used as the pass device with little electronics to control it. In addition, putting things like pulses on the output of the throttle will make the low speed control a lot better than pure DC. When setting the whole system up, don't forget to put some fast acting circuit breakers on each of the throttles so that shorts don't kill off the layout from the high currents available from batteries. Even a 1 ohm resistor of large wattage in series with the throttle will help a lot.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!
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.
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