Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Super-Bright Flash of Light, Car Shut Down?

  1. Jun 8, 2012 #1
    This experience happened to me, my uncle, and 2 cousins several years ago. None of us have a logical explanation for it. I'm not saying it was anything paranormal, or not; I'm just wondering what all of your thoughts are:

    Myself, my two cousins, and my uncle were camping in western South Dakota at a campground called Red Bank Springs. It's essentially out in the middle of nowhere (i.e. 10 grassy overgrown spots in the campground, a single outhouse, only running water comes from a spring, so you have to drive 10 miles for drinking water). We'd left that night to get water at a church camp about 10 miles away from our campsite, and my uncle got to talking with someone at the camp, so by the time we left it was around 11:30-12:00 at night. We were driving in my uncles pickup down a typical gravel road, about 3 miles away from our camp. The night was clear and dry, stars were out, probably 80 degrees. All of a sudden, we hit a pothole, a deer ran across the road in front of us, and there was a -blinding- flash of light that light up the entire field around us, and the outline of the hills beyond that, for a split second. There was no noise. At the same time, the pickup shut off, the cd ejected from the cd player, and the truck rolled to a stop, completely dead.

    The first thought we all had, after discussing it, was the thought of heat (as in, we were afraid to touch the windows because we thought they would be super-hot). The light was that intense. I thought, in the next three seconds after the flash, that we were about to start on fire or explode. It wasn't a panicked thought, that's just how intense the light was. The second thought we all had, that we all sheepishly admitted later, was aliens or something supernatural.

    We sort of sat there in stunned silence for a minute, my uncle realized we very likely had 3 miles to walk in the dark, when he decided he'd give the truck a start and hope it somehow worked. As he was reaching for the key, the car started back up and the CD slid back into the player. He hadn't touched the key yet.

    The next day we drove in to see a mechanic, and the mechanic found the battery wires were frayed/corroded super bad, but he had no explanation for what could have happened either.


    So thoughts? Take care!
     
  2. jcsd
  3. Jun 8, 2012 #2

    collinsmark

    User Avatar
    Homework Helper
    Gold Member

    Hello sharpshoey,

    Welcome to Physics Forums!

    I'll try to give one plausible (at least possible) explanation. I'm not saying my explanation is definitely what happened, but rather just that it is not outside the realm of possibilities.

    Perhaps the flash came from an electrical arc inside the engine compartment itself. Here is scenario that might explain it.

    [1] It was night and you, your two cousins and uncle were essentially in the middle of nowhere, and had been in relative darkness for awhile. Meaning that your eyes were pretty well (at least partially well) adjusted to the darkness. Even a mildly bright flash would seem extremely bright in that situation. (I'm sure at home in the middle of the night, at some point or another, you have turned on a light [perhaps after waking up from sleep for example] and could hardly stand to keep you eyelids open, so I'm sure you know how bright things can seem after being in the dark for an extended period.)

    [2] A wire within the engine compartment, I'm guessing a spark plug wire, was frayed, exposing the bare wire to some extent. Let me get into some technical details before continuing (some of which depend on particular car electronics, so I'll try to keep it general). The truck's 12-15 electrical system's energy comes from the battery and also the alternator after being rectified with a rectifier and capacitor (in part). This 12-15 Volt source is routed to other components of the truck, including the CD player and ignition system. The ignition systems routs the current path to the specific spark plug that needs it at the moment, and also steps up the voltage to somewhere around 12,000–25,000 Volts. 12,000 to 25,000 Volts is enough to produce a considerable electrical arc. However, at the beginning of the drive the bare wire was not near any other part of the engine so no arc occurred.

    [3] The truck hit a pot hole causing the spark plug wire to wobble toward the engine block (which is grounded) and the bare part of the wire was critically close to the engine block at just the time associated spark plug was timed to go. Spark plugs generally include some series resistance to reduce RF noise when firing. But no such series resistance was between the frayed wire and the engine block, meaning the bare-wire/engine block path is the path of least resistance could produce a larger electrical arc than a typical spark plug. And that was the source of the flash. The flash could have been visible outside the truck mostly by wide opening under the car, but also gaps in the radiator grill and engine hood. If you want to know how bright an electrical arc can be, realize that arc welders use a heavily tinted welding mask and they work with less than 80 Volts. An arc caused by 12,000–25,000 Volts could be very bright in comparison. And you weren't even wearing a welding mask.

    [4] The lack of series resistance in the path might also explain the engine stopping in addition to the brighter spark. With no series resistance to constrain the current, it may easily drain the energy stored in the ignition system's capacitance, stopping other spark plugs form firing, at least until the capacitor bank is able to recharge. The time for the capacitor to recharge might have taken somewhere on the order of a second or perhaps several seconds, but it would be enough time to the engine to shut down anyway (10s of seconds seems like a too long of a time, but I don't know, perhaps it's not outside the realm of possibility). During this time, the truck's 12-15 Volt electrical system would have been considerably lower than normal.

    [5] Many modern CDs have a feature that automatically ejects the CD if the supply voltage is detected to be low. There is a good reason for that. If the truck's electrical system's voltage is low, it's a signal that the alternator and/or battery are about to go kaput. And if the battery and/or alternator is about to go kaput, at least your CD won't be trapped in the CD player until you get your car repaired. Having to get the car towed to replace the alternator is bad enough. But being without your favorite CD the whole time makes it worse. Not all automotive CD players have this feature, but perhaps the one your uncle has does.

    That's harder to explain.

    Was your uncle's truck a stick-shift? And were you on a incline? If so, that might explain it, maybe. In the confusion, your uncle may have neglected to put the transmission in neutral as the truck stopped. When trying to start the truck again, he may have instinctively moved his foot from the brake to the accelerator pedal, even before he reached for the ignition. By releasing the break, the truck started rolling down the incline, and since the transmission was still in gear, perhaps it was enough to get the engine started, even without using the starter motor (people that have stick-shifts use this trick all the time if they can't find a jump-start. It's not uncommon.). With the engine and alternator going again, it would be enough to get the system voltage back up above the CD's threshold. The CD player, now detecting a partially inserted CD, took the CD back in.

    A short circuit in the 12 V battery wire (which may have had 15 V at the time) itself could explain everything you've described too, except that I doubt it could explain the bright flash. 15 V is enough to make an arc, but not a really, really big one. Maybe it's related though. If the frayed spark plug wire came into contact with a frayed battery wire (instead of the engine block like I presumed above), it might explain the same symptoms, except that it could cause further damage to the battery wire. Or, perhaps the frayed battery wire came into contact with some otherwise stationary high voltage part of the ignition system (instead of the other way around).

    Of course, I'm just speculating about all of this. All I'm saying is that I think a frayed wire coming into contact with a high voltage part of the ignition system (or vise versa), thus causing an electrical arc, is not outside the realm of possibilities, and it might explain the experience.
     
    Last edited: Jun 8, 2012
  4. Jun 8, 2012 #3
    Deer, pothole, blinding light, truck stops, truck re-starts, no loud sound.
    I am just wondering why the hood didn't pop open, headlights burst, and all the coyotes in the area didn't start howling!

    Recollection of events of this (traumatic) nature usually are adds ons and/or deletions and changie with time and what one thinks one remember happeneing several years ago probably actually did not. No doubt you have had discussions about this event amongst yourselves and with others, with questions and answers that have become ingrained as part of the the memory. If you had written the story down immediately after the event as a record then that would have had less deviation from actuality.

    Police and other investigators have to be very careful so as not to imprint into the memory of witnesses. Eye witnesses evidence is not as accurate as you may be lead to believe.
    http://www.psychology.iastate.edu/~glwells/Wells_articles_pdf/pspi_7_2_article[1].pdf

    When presented with a threat of their life , such as in an armed robery, mugging, most people focus on the threatening object pointed at them be it a knife, gun, and will scaintly be able to describe what the assailant was wearing, color of hair, race, shoes, face, and other factors that could lead to a 'positive' identification.
    http://www.visualexpert.com/Resources/mistakenid.html

    Although you may be under the impression that I am belittling your event, rest assured that that is not the case - something happened but what is not clear.
    Two things intigued me was the fact that you mentioned 'no noise' - an obvious omission. Hitting a pothole makes noise and someone, your uncle must have definetely, like most folk, have uttered an s- or d-work, or just "look out!!"
    Which led me to ponder about the second that being the deer at the same time crossing your path. This seems to be an addtion to memory, or a transfer. Could you possibly not have seen a deer by the side of the road a few miles back and it has now become mingled in as becoming part of the event.

    Sorry to be a part pooper but thats just the way I am.
    All the best.

    Memory - several years back a song was written and pefrormed by a man and woman, recollecting their romance. In the song they disagree about everything from what they were wearing to the weather. I can't remember the name of the song but it certainly shows how two people can descibe an event completely differently and what is in the details. Happens to everyone.
     
    Last edited: Jun 8, 2012
  5. Jun 8, 2012 #4
    This is a ridiculous objection. It's clear the OP meant there was no noise associated with the flash of light.
     
  6. Jun 8, 2012 #5
    I hit a dip in the street going a bit too fast once, bounced hard, and the car suddenly died. I couldn't restart it and had it towed home. It was night so I didn't look under the hood till the next day. Couldn't see anything wrong, except that the battery wasn't clamped down. Apparently the bump had jarred it loose from the hold down clamp. Consulting the manual I discovered there was a thing called a "fusible link" that was connected directly to the battery. Opening the little case that covered the link, I saw the wires had been pulled and contact with the link was broken.

    So, my theory about your car is that your battery came loose from its hold down when you hit the pothole, pulling on all the wires connected to it, pulling something major out of electrical contact shutting the car off, but it crept back after the shock, re-establishing contact. (Any stretched rubber or plastic wire coating might creep back into shape after being stretched suddenly.)

    My only idea about the flash is heat lightning, and the deer was just a deer. The coincidence of all three...stuff like that happens now and then.
     
  7. Jun 9, 2012 #6
    Wow, thanks a lot for the replies everyone. Collinsmark, that is an excellent, well detailed and very plausible explanation. In answer to your questions 1) It wasn't a stick shift, 2) it was on about as flat a stretch of road as you can get, 3) we sat there completely dead (no interior lights, radio or dashboard lights, or anything) for at least 1 full minute, probably closer to 2. As far as my uncle's feet, I have no idea on that ;)

    Zoobyshoe: Another very plausible explanation, however can this explain how the truck restarted?

    256bits: I understand where you're coming from, however I respectfully disagree on this one. At the time, my uncle did a good job of not seeming concerned in the slightest, and so at the actual time of the event, none of us were freaking out or even really concerned. I wouldn't consider it "traumatic" in nature, just very very strange. I am very confident that my recounting is very, very accurate. As far as the deer running across the road, I wasn't meaning to imply it had anything to do with things, just adding in a detail I remember. But we'll just have to agree to disagree I think.

    Thank you all for your replies!
     
  8. Jun 9, 2012 #7
    As I speculated, whatever wire was pulled out of contact re-established contact when the distended plastic or rubber insulation covering the wire crept back into shape during the minute you sat there.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Super-Bright Flash of Light, Car Shut Down?
  1. Light<>Bright (Replies: 21)

  2. Super (Replies: 17)

Loading...