[C1] What Voltage to Ballast Resistor?
12-05-2017, 06:11 AM
#21
Team Owner
Kill me, kill me now...
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new vette 62 (12-05-2017)
12-05-2017, 08:08 AM
#22
Drifting
GearheadJoe,
Thanks for the information, I'm a mechanical / Industrial Engineer and the only thing I remember from school is if you have an electrical problem, get yourself an electrical technician. I had picked up the car from a fabricator and was test driving it when it started to rain. turned on wipers, engine quit.
Turns out the engine had been out of the car twice and on second install, the wiper was attached to the wrong side of Ballast resistor. Speaking as a non-electrical I think its a dumb place to power the wipers.
Thanks to everyone for the education.
Marty
Thanks for the information, I'm a mechanical / Industrial Engineer and the only thing I remember from school is if you have an electrical problem, get yourself an electrical technician. I had picked up the car from a fabricator and was test driving it when it started to rain. turned on wipers, engine quit.
Turns out the engine had been out of the car twice and on second install, the wiper was attached to the wrong side of Ballast resistor. Speaking as a non-electrical I think its a dumb place to power the wipers.
Thanks to everyone for the education.
Marty
Hi Marty:
I'm happy to hear that the problem has been resolved.
12-05-2017, 08:40 AM
#23
Team Owner
GearheadJoe,
Thanks for the information, I'm a mechanical / Industrial Engineer and the only thing I remember from school is if you have an electrical problem, get yourself an electrical technician. I had picked up the car from a fabricator and was test driving it when it started to rain. turned on wipers, engine quit.
Turns out the engine had been out of the car twice and on second install, the wiper was attached to the wrong side of Ballast resistor. Speaking as a non-electrical I think its a dumb place to power the wipers.
Thanks to everyone for the education.
Marty
Thanks for the information, I'm a mechanical / Industrial Engineer and the only thing I remember from school is if you have an electrical problem, get yourself an electrical technician. I had picked up the car from a fabricator and was test driving it when it started to rain. turned on wipers, engine quit.
Turns out the engine had been out of the car twice and on second install, the wiper was attached to the wrong side of Ballast resistor. Speaking as a non-electrical I think its a dumb place to power the wipers.
Thanks to everyone for the education.
Marty
12-05-2017, 11:18 AM
#24
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No I don't. Any series circuit will read source voltage at any point in that circuit when no current is flowing (points open). No current flowing through ballast, no voltage drop, so 12v Ohm's law. When current starts flowing, (points closed) ballast will drop its portion. The coil does it's own thing with inductance and collapsing fields, but the ballast RESISTER drops voltage according to Ohm's law any time there is current flowing.
.It all ties together with Ohm's law since adding resistance in series increases total circuit resistance reducing current flowing when source remains constant and path is complete. Voltage drop can be read across ballast with points closed, but you get source when open. I realize you know how it works, and explained it well, but I don't understand your disdain for Ohm's law. They didn't name it " Ohm's incorrect theory.
Regardless, you still connect wipers to ignition side of ballast to get 12v.
.It all ties together with Ohm's law since adding resistance in series increases total circuit resistance reducing current flowing when source remains constant and path is complete. Voltage drop can be read across ballast with points closed, but you get source when open. I realize you know how it works, and explained it well, but I don't understand your disdain for Ohm's law. They didn't name it " Ohm's incorrect theory.
Regardless, you still connect wipers to ignition side of ballast to get 12v.
My "disdain" is when incorrect information is offered up to posters/members who are trying to fix their cars. A ballast is not there to reduce the voltage in the system to protect the points. The points have to deal with 12 volts (or actually 13-14 if someone wishes to be picky) every time the points are open and also when discharging the condenser when the points close. The ballast does nothing to prevent the points from dealing with this "high" 12 volt "danger". Additionally, 12 volts is child's play compared to the 150-200 volts that the points contend with every time the points open and ignition is initiated.
Just because these are old cars does not mean we have to adhere to old wives' tales. (Although I believe Jim Lockwood is probably correct with his earlier comment.)
12-05-2017, 11:51 AM
#25
Team Owner
I have no disdain for Ohm's law. I got paid for years to spend a good portion of my daily time at work using E=IR and its combinations.
My "disdain" is when incorrect information is offered up to posters/members who are trying to fix their cars. A ballast is not there to reduce the voltage in the system to protect the points. The points have to deal with 12 volts (or actually 13-14 if someone wishes to be picky) every time the points are open and also when discharging the condenser when the points close. The ballast does nothing to prevent the points from dealing with this "high" 12 volt "danger". Additionally, 12 volts is child's play compared to the 150-200 volts that the points contend with every time the points open and ignition is initiated.
Just because these are old cars does not mean we have to adhere to old wives' tales. (Although I believe Jim Lockwood is probably correct with his earlier comment.)
My "disdain" is when incorrect information is offered up to posters/members who are trying to fix their cars. A ballast is not there to reduce the voltage in the system to protect the points. The points have to deal with 12 volts (or actually 13-14 if someone wishes to be picky) every time the points are open and also when discharging the condenser when the points close. The ballast does nothing to prevent the points from dealing with this "high" 12 volt "danger". Additionally, 12 volts is child's play compared to the 150-200 volts that the points contend with every time the points open and ignition is initiated.
Just because these are old cars does not mean we have to adhere to old wives' tales. (Although I believe Jim Lockwood is probably correct with his earlier comment.)
12-05-2017, 12:10 PM
#26
Drifting
Oversimplification has taught us that a ballast resistor reduces voltage to the coil once an engine has started thereby extending the life of the coil and the points. This information has served generations of mechanics over untold numbers of miles traveled. What more is it necessary to know?
12-05-2017, 12:22 PM
#27
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I'm done with this silly word play. If you don't think the resistor drops any voltage connect the meter to the ignition side with the car running and then connect it to the bottom side and see how much lower the voltage is. It doesn't fit your narrative, but in fact it does drop the voltage whether it's the purpose or not. Speaking of purpose, I see no purpose in commenting any further so I'm out.
But there is a purpose. Both of you are very smart guys whose help is invaluable to others here, and you are both right. There is no reason to have a disagreement.
I'm not an EE but I have a lot of EE background as a former telephone company employee. I'm not a MA or PhD in English literature but it was my major for my BA in College. As such I'm always interested in the proper use of language and terminology. With technical issues its important everyone speaks the same language.
The salient point here is that while a ballast in a circuit has the effect of dropping voltage it is the consequence of the purpose of the ballast, which is to limit current flow. Its important to say that. An ignition circuit cannot be properly understood without it.
In discharge lighting for example (fluorescent, mercury vapor, metal halide, etc.) a ballast is required in the circuit because once the arc is established in such a lamp its resistance goes to zero. The ballast is essential and present to prevent a direct short by limiting current through the lamp just as it does in an ignition coil. It also lowers the voltage to the lamp, but no electrician would tell you the purpose of the ballast is to drop the voltage to the lamp.
Why should such a distinction get anyone's skivvies in a Bunge?
Dan
12-05-2017, 12:27 PM
#28
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The Voltage drop across the ballast is a by product of the current flow, not its reason for being.
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12-05-2017, 12:28 PM
#29
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12-05-2017, 12:31 PM
#30
Safety Car
I'm done with this silly word play. If you don't think the resistor drops any voltage connect the meter to the ignition side with the car running and then connect it to the bottom side and see how much lower the voltage is. It doesn't fit your narrative, but in fact it does drop the voltage whether it's the purpose or not. Speaking of purpose, I see no purpose in commenting any further so I'm out.
Simple stuff like Ohm's law and series circuits are easy enough for this ME to understand, and this is how I remember it:
https://www.swtc.edu/Ag_Power/electr...s_circuits.htm
12-05-2017, 04:27 PM
#31
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I'm done with this silly word play. If you don't think the resistor drops any voltage connect the meter to the ignition side with the car running and then connect it to the bottom side and see how much lower the voltage is. It doesn't fit your narrative, but in fact it does drop the voltage whether it's the purpose or not. Speaking of purpose, I see no purpose in commenting any further so I'm out.
Also, there is an Ignition Physics sticky in C3 Tech that explains everything in greater detail.