OK so it's been raining here off and on for days now and I need something to do. I've on hand a spare resistor plate. The one behind the heater core. The one that has caused a few fires. Debri gets all in behing the plate, Feifel the mouse builds his family a nice 3 room house in there, god knows what else can happen in there.
So. I have actually been thinking of this for sometime now, with that in mind I saved some actual debri that I found behind one of these nice resistor plates. Have some of it in a coffee can staying nice and perserved, stuff was bone dry in there.
Ok so this is what we need to do.
1. Mock up a enclosure to stick our resisitor in, one we can see into easily. One that will closely simulate the same conditions as would be present typically in a fiero. I have some vent ducts from a parts purchase. However couldn't, for our purposes, we just use a cardboard shoe box?
2. Determine what peak voltage the resistor plate would typically get during normal usage. Could I just hook my battery charger up to the resistor terminals? Carefully that is, maybe use some alligator clips and bits of wire?
3. Get out our video camera and see what happens.
So please chime in! Lets see what happens, plus it could be fun! Lets go discovery channel on it and Confirm or Busted!
I like most Fiero owners got mine after it had sat for 8+ years under a tree, and did find some crap/nests in that area as well as behind blower motor, the tail lights, frame behind the rear bumper and ....somewhere else, can't recall, but would like to see how easily that thing will start a "nest fire". I would think (no expert) that you could just give it 12v and see what happens to it with no nest, (does it glow?) then add a nest and try again. Doesn't need to be in the actual space, coffee can would work, or shoe box etc. even just on a table would be fine for a what if.
Heres some debri I saved. Pine needles and other stuff. This stuff is the actual stuff that came out of one of our cars. I think this should be enough to at the very least get a reaction. We can try other stuff later, dryer lint makes great fire starter, perhaps birch tree bark. Birch bark burns like crazy, even sopping wet it will burn! We can worry about this later though.
Now think about our mock up enclosure...back to the lab! Any help with this? Cardboard box?
Please chime in here as I'm reaching and I really wanna see if we can burn a fiero! We have all of the ingredients we just need to provide to proper enviroment.
I like most Fiero owners got mine after it had sat for 8+ years under a tree, and did find some crap/nests in that area as well as behind blower motor, the tail lights, frame behind the rear bumper and ....somewhere else, can't recall, but would like to see how easily that thing will start a "nest fire". I would think (no expert) that you could just give it 12v and see what happens to it with no nest, (does it glow?) then add a nest and try again. Doesn't need to be in the actual space, coffee can would work, or shoe box etc. even just on a table would be fine for a what if.
Hehe, pretty fun already! Im thinking our enclosure needs to have a spot for airflow. Airflow that the resistor would normally be subject to with the blower on. I'm thinking we could rig a hairdryer to it somehow. Set the hairdryer on no heat setting and just use it as a blower. Momma here has one of these hairdryers...
We will definately test the plate with just peak voltage first and see if it gets hot. Wish we had one of those temp scopes we could point at it. Perhaps we can come up with a home made way to read temps?
Dude you have WAY too much time on your hands...hehe good luck with whatever this is, not real sure why your wanting to do that but hey if it makes you giggle then so be it. Peace
Dude you have WAY too much time on your hands...hehe good luck with whatever this is, not real sure why your wanting to do that but hey if it makes you giggle then so be it. Peace
Pete
I knew someone was gonna say this Lol.. It's been raining for days here. I'm between projects. I passed on a waste water treatment remodel job for obvious reasons. I don't do poo well...Just waiting till the next job starts up. Should be a CMP job, power dist. center...working for the man bites!
See where my thumb is? Thats where all the debri will collect. Either through the effects of the blower or Fiefel the mouse. It gets piled up back there behind the resistor plate till it starts to come into physical contact with the resistors. Thats when the fire danger begins, perhaps?
Heres an edited pic showing airflow as I understand it thus far and where the debri will collect..pls forgive my editting...
The brown represents debri. Theres a tight corner back there when its all together in a typical car. This is directly behind the heater core. As stated the debri piles up here one way or another.
So we need our mock up to have the plate located in a tight corner.
I knew someone was gonna say this Lol.. It's been raining for days here. I'm between projects. I passed on a waste water treatment remodel job for obvious reasons. I don't do poo well...Just waiting till the next job starts up. Should be a CMP job, power dist. center...working for the man bites!
Ok heres another step. No worries these are all spare parts I picked up, might as well get some use out of them before they hit the trash can. Plus it's science
Were thinking 12v from purple to green? We need to think about amperages. What would be the peak amperage? Anyone have any thoughts on this?
K heres our mock up! Were almost ready to have some serious fun!!
Put my meter on there just so we could see whats going on.
More too come. Digging out the video cam for this test! Might take a bit to upload the vid with our cursed used computer we bought...shoulda known better there. Anyway vid next of the first test.
There is a slight flaw in your mock-up. You're using the resistor as the only load on the system. In real life, when installed in the Fiero's heater box, the blower motor is the bigger load. Most of the load (and, therefore, heat creation) will be in the blower motor. Yes, since the resistors provide a slight load they do get warm, and lower blower speeds will produce more heat since the resistor becomes more of a load and the blower becomes less of a load, but with a properly operating blower they won't get nearly that hot in real life.
Case in point: connect a 12V light bulb directly to the battery terminals using 18G wires. The bulb is the load, and the bulb gets warm, but the wires don't. Now, take the bulb out and connect the 18G wires together with no load. The wires will instantly get so hot that they will probably vaporize. The bulb in this scenario represents the blower motor. There has to be a load on the system or you get what's called a direct short and the sparks and fire that go along with it.
It's Ohm's Law: I = V/R, where I is current (in amps), V is pressure (in volts) and R is resistance (Ohms). When voltage remains the same but resistance in the circuit decreases, amperage will increase.
In order for your scenario to be realistic, you need to connect a blower motor in the circuit. You could approximate it by using another resistor with the same resistance as the Fiero blower motor, but it won't be 100% accurate due to the inductance of the motor when operating. Inductance changes the relationships of Ohm's law slightly, but probably not enough in this situation to produce noticeable differences.
Cool test though!
[This message has been edited by aircraft_electrician (edited 05-04-2012).]
There is a slight flaw in your mock-up. You're using the resistor as the only load on the system. In real life, when installed in the Fiero's heater box, the blower motor is the bigger load. Most of the load (and, therefore, heat creation) will be in the blower motor. Yes, since the resistors provide a slight load they do get warm, and lower blower speeds will produce more heat since the resistor becomes more of a load and the blower becomes less of a load, but with a properly operating blower they won't get nearly that hot in real life.
Case in point: connect a 12V light bulb directly to the battery terminals using 18G wires. The bulb is the load, and the bulb gets warm, but the wires don't. Now, take the bulb out and connect the 18G wires together with no load. The wires will instantly get so hot that they will probably vaporize. The bulb in this scenario represents the blower motor. There has to be a load on the system or you get what's called a direct short and the sparks and fire that go along with it.
It's Ohm's Law: I = V/R, where I is current (in amps), V is pressure (in volts) and R is resistance (Ohms). When voltage remains the same but resistance in the circuit decreases, amperage will increase.
In order for your scenario to be realistic, you need to connect a blower motor in the circuit. You could approximate it by using another resistor with the same resistance as the Fiero blower motor, but it won't be 100% accurate due to the inductance of the motor when operating. Inductance changes the relationships of Ohm's law slightly, but probably not enough in this situation to produce noticeable differences.
Cool test though!
Yes I'm familiar with Ohms law. 24 years as an electrician, commercial/industrial/residential, no aircraft tho . There are probably lots of flaws in our experiment. This was only for fun. Something to do on a rainy day.
I do know there have been fires from this area in the past. I've seen a few pics of cars that have met their demise because of this. So I do feel it's plausable.
Bump for the guy that just lost a mint 85GT with less the 12K miles to this over on the FAAUSFA FB page.
Sad loss to the Fiero family. Luckily everyone got out safe! So with spring fast approaching and many of our cars coming out of hibernation, please check those resistors. It takes 5 mins and a socket to pull the resistor and inspect. If your car has been parked this is Fievel's favorite spot!
Originally posted by aircraft_electrician: There is a slight flaw in your mock-up. ....... with a properly operating blower they won't get nearly that hot in real life.
Sorry, but not completely true. It is WELL documented that fires start with debris being ignited by the resistor. We know that as fact. Sure, the airflow from the fan is supposed to keep the resistor cool, that is why it is in the blower intake in the first place. When you shut the car off, there is no more current, so the resistor can not increase in temperature. So for the fires to start, the heat HAS to be generated while the fan is on. There is no other way around it.
quote
Originally posted by weloveour86se: Soo, Comfirmed or Busted?
100% CONFIRMED!
This is a real world case of what happened to Andrew's 1984 Fiero It was proven to have started in the blower intake. Also, as for the "they won't get nearly that hot in real life", keep in mind the air blowing over the resistor that day was well below freezing, and it still generated enough heat to begin the smoldering process.
[This message has been edited by JohnWPB (edited 02-11-2015).]
Any help with this? Cardboard box?
It was proven to have started in the blower intake. Also, as for the "they won't get nearly that hot in real life", keep in mind the air blowing over the resistor that day was well below freezing, and it still generated enough heat to begin the smoldering process.
