This is the best video on this subject that I have seen (and I have watched a lot of them). I am attempting to determine whether I have a bad coil or condenser and this has helped considerably.
Here is my short guide to condenser testing: 1. Using a meter with a capacitance function, measure the capacitance. Ideal spec is 200-250 nF; up to 350 nF is probably OK if it's stable. 2. Using the resistance function, measure the resistance. You should see the readout gradually increment up until it reaches infinity. If the readout plateaus at some number of ohms, that indicates leakage. 3. Place the condenser and the multimeter in series with a battery and measure the amperage. You should see the amps start at some number and drop to zero. If the amps don't reach zero, that indicates leakage. 4. Heat the condenser gently until it reaches about 150° and repeat tests 1-3.
@@alexiskai Thank you! My capacitor (for a Ford V8) reads .33 microfarads at room temperature. I am heating it in the oven to see how it behaves under heat. I had an ignition failure the other day and swapped coil and capacitor on the road to get home. I am attempting to determine which of the two parts failed (the coil passed the heat test yesterday). The meter to measure capacitance arrived late yesterday so the condenser tests are today. I would not have known how to test the condenser without your video.
@@RAK402 I've heard that new V8 condensers are less reliable these days. Interested to see what you find. I do have a video on testing coils, but for that you need special equipment.
Great job! Electrical and automotive electronics are areas where many people stumble. Either that or like me, that comes easy but I cannot teach or explain worth a darn. You are gifted with both the understanding and the ability and the desire to pass this on to others.
The other day I wanted to know how to test a capacitor with my kaiweets meter but ended up troubleshooting it down to the cap without it. Today I decided on digging into model a ignition and found your video... 2 for 1!!
Back in the day, you had special capacitor testers which used a high voltage (usually the voltage the cap was rated to) in order to detect leak current. Some caps might also be perfectly fine under the low voltage that a multimeter uses, but arc through if you give it the juice it actually has to operate around. Makes for some funny behavior in tube radios - a radio might work fine for a minute, then as it warms up, stations start drifting, weird oscillating circuits form by themselves creating R2D2 noise... Come to think of it, a car's ignition system isn't too far away from an oscillating circuit - I wonder what was first, the radio or electronic ignition!
Remix this and make it an intro into ignition systems and capacitors -- you should have 300k views by now for this quality content, just needs some rebranding (it's not really a Model A Ford video, that's more of an intro)
Yeah but then I'd have a bunch of classic car guys saying I got the ground polarity wrong. 🤷♂ Thanks though. Once I finish my series on engine disassembly and inspection, maybe I'll circle back to this one.
Nice video, nice explanation. For Model A, your drawing had the ignition switch on the wrong side of the coil (although it didn't affect the discussion).
@@alexiskai no prob! It was a great video, and oh, by the way, cost me money, since I just ordered my own Kaiweets ammeter! Geese, another new toy to add to my collection!
The tiny amount of energy stored in the condenser makes no difference to the spark. It just protects the points. Condenser is around 300nF. That ends up with about a 7microJoule of energy when charged. The magnetic field in the coil inductance is where all the energy is stored. The primary inductance is 5.5mH with 1 to 1.5ohms resistance it typically charges to 2amps. That is 11mJ, 1500 times more energy than the condenser. Another different more modern type of ignition system known as CD for Capacitive Discharge does store the energy in a capacitor and use the ignition coil more as a step up transformer. These run the primary side more like 600Volts. A bad condenser can ruin the spark by sapping energy from the coil, fouling the points due to arcing, and altering the timing of the spark. The current wants to keep going the same direction in the coil primary when the points open and resistance goes very high. This causes the reverse voltage. This is why you need to protect silicon switching devices like transistors from this high reverse voltage of inductors.
Do these Kaiweets meters digital display show a stable reading when the engine is running? A lot of digital meters displays jump all over the place and that's when I use a analog meter.
If it's a lead-acid battery, i.e. a rechargeable one, then applying a higher voltage to a circuit than the battery itself is putting out will essentially charge the battery. That's how you charge the battery on a daily basis - you just put it into a circuit where something else is putting out a higher voltage. You can apply any voltage to the battery, but there are physical limitations to how much it can absorb in a given time. That's why a battery charger will put out only 1-2V above the battery's normal output. Anything above that just becomes heat. But for the fraction of a second that a capacitor is discharging, the battery will happily absorb 200V or whatever it's throwing out.
It doesn't. He confused all the current voltage reversals. The capacitor doesn't charge the battery with a reverse voltage, if it had a higher forward voltage then it might. The coil is disconnected before the reverse voltage spike so that doesn't see the battery.
@@alexiskai there is no energy in the condenser when the points open. They were shorting across the condenser when closed. If you have an oscilloscope you can probe around to see how this works.
Very good explanation but 1 major shortfall. You presented an analog and a digital volt meter in the beginning...and my expectations were that you would use all three ,starting from the simple analog meter and then moving up to your fancy amp clamp. I have an old radio shack analog meter and a cheap walmart DOM, but not an amp clamp.....I was especially expecting use of the analog..., because the condensers were for very old cars..., long before we had digital devices.
Interesting critique. The clamp meter is the only one of the three I own that can do capacitance testing, and its display is much easier for viewers to read, so that's the one I went with. The alternative would be to make an already-long video maybe 50% longer by duplicating the tests. The tests are straightforward in execution and should be able to be replicated by others using basic multimeters (except for the capacitance testing, which requires a separate meter).
@alexiskai some other people test capacitor ,not for the actual value, but just for building charge. Using a very high resistance setting, connect to the capacitor and watch the resistance climb as it charges...and then goes OL, or with the analog the meter pegs. While it does not prove what the actual capacitance is, it does show that there is no dead short, there is no open circuit, and it does take a charge. Some bad capacitors can beep just on the continuity setting, or the opposite can happen where there is an open and the meter shows OL , or the dial does not move at all. If you have a known good capacitor, you can compare the value of resistance achieved , right before it goes OL ..out or range.
@alexiskai yes, but you used the high tech meter. You did not mention or show that you could have used the 40 year old or greater analog meter that was introduced in the beginning.
This is the best video on this subject that I have seen (and I have watched a lot of them). I am attempting to determine whether I have a bad coil or condenser and this has helped considerably.
Awesome. Leave another comment if you hit a wall with the troubleshooting, I'll see if I can help any.
Here is my short guide to condenser testing:
1. Using a meter with a capacitance function, measure the capacitance. Ideal spec is 200-250 nF; up to 350 nF is probably OK if it's stable.
2. Using the resistance function, measure the resistance. You should see the readout gradually increment up until it reaches infinity. If the readout plateaus at some number of ohms, that indicates leakage.
3. Place the condenser and the multimeter in series with a battery and measure the amperage. You should see the amps start at some number and drop to zero. If the amps don't reach zero, that indicates leakage.
4. Heat the condenser gently until it reaches about 150° and repeat tests 1-3.
@@alexiskai Thank you! My capacitor (for a Ford V8) reads .33 microfarads at room temperature. I am heating it in the oven to see how it behaves under heat. I had an ignition failure the other day and swapped coil and capacitor on the road to get home. I am attempting to determine which of the two parts failed (the coil passed the heat test yesterday). The meter to measure capacitance arrived late yesterday so the condenser tests are today. I would not have known how to test the condenser without your video.
@@RAK402 I've heard that new V8 condensers are less reliable these days. Interested to see what you find. I do have a video on testing coils, but for that you need special equipment.
@@alexiskai Thank you again!
Great job! Electrical and automotive electronics are areas where many people stumble. Either that or like me, that comes easy but I cannot teach or explain worth a darn. You are gifted with both the understanding and the ability and the desire to pass this on to others.
The other day I wanted to know how to test a capacitor with my kaiweets meter but ended up troubleshooting it down to the cap without it. Today I decided on digging into model a ignition and found your video... 2 for 1!!
Very thorough capacitor lecture! I learned several things I did not know! Thanks, Tom
Back in the day, you had special capacitor testers which used a high voltage (usually the voltage the cap was rated to) in order to detect leak current.
Some caps might also be perfectly fine under the low voltage that a multimeter uses, but arc through if you give it the juice it actually has to operate around.
Makes for some funny behavior in tube radios - a radio might work fine for a minute, then as it warms up, stations start drifting, weird oscillating circuits form by themselves creating R2D2 noise...
Come to think of it, a car's ignition system isn't too far away from an oscillating circuit - I wonder what was first, the radio or electronic ignition!
On the HT208D, the resistance test goes up to 250V, so it's not perfect but better than many multimeters.
@@alexiskai Chapeau, not bad!
Thank You I need all the help I can get when it comes to Model A electrical!
Another great video Alex.
very good explanation thanks chris
Remix this and make it an intro into ignition systems and capacitors -- you should have 300k views by now for this quality content, just needs some rebranding (it's not really a Model A Ford video, that's more of an intro)
Yeah but then I'd have a bunch of classic car guys saying I got the ground polarity wrong. 🤷♂ Thanks though. Once I finish my series on engine disassembly and inspection, maybe I'll circle back to this one.
Nice video, nice explanation. For Model A, your drawing had the ignition switch on the wrong side of the coil (although it didn't affect the discussion).
Good eye. Yeah, I guess the diagram is cleaner with the switch out of the way.
@@alexiskai no prob! It was a great video, and oh, by the way, cost me money, since I just ordered my own Kaiweets ammeter! Geese, another new toy to add to my collection!
@@kdog622 Fun trick, you can use it to check the amperage draw for your starter. Mine topped out at 155A, which I gather is within normal parameters.
@@alexiskai thanks! I plan on checking that!
Thanks for do this.
The tiny amount of energy stored in the condenser makes no difference to the spark. It just protects the points. Condenser is around 300nF. That ends up with about a 7microJoule of energy when charged. The magnetic field in the coil inductance is where all the energy is stored. The primary inductance is 5.5mH with 1 to 1.5ohms resistance it typically charges to 2amps. That is 11mJ, 1500 times more energy than the condenser. Another different more modern type of ignition system known as CD for Capacitive Discharge does store the energy in a capacitor and use the ignition coil more as a step up transformer. These run the primary side more like 600Volts.
A bad condenser can ruin the spark by sapping energy from the coil, fouling the points due to arcing, and altering the timing of the spark. The current wants to keep going the same direction in the coil primary when the points open and resistance goes very high. This causes the reverse voltage. This is why you need to protect silicon switching devices like transistors from this high reverse voltage of inductors.
Thank You, well done
Thanks Mitch
Do these Kaiweets meters digital display show a stable reading when the engine is running? A lot of digital meters displays jump all over the place and that's when I use a analog meter.
For what measurement specifically?
How can the high DC voltage reverse back into the battery?
If it's a lead-acid battery, i.e. a rechargeable one, then applying a higher voltage to a circuit than the battery itself is putting out will essentially charge the battery. That's how you charge the battery on a daily basis - you just put it into a circuit where something else is putting out a higher voltage. You can apply any voltage to the battery, but there are physical limitations to how much it can absorb in a given time. That's why a battery charger will put out only 1-2V above the battery's normal output. Anything above that just becomes heat. But for the fraction of a second that a capacitor is discharging, the battery will happily absorb 200V or whatever it's throwing out.
It doesn't. He confused all the current voltage reversals. The capacitor doesn't charge the battery with a reverse voltage, if it had a higher forward voltage then it might. The coil is disconnected before the reverse voltage spike so that doesn't see the battery.
@@vinnieluther6589 Where does the energy stored in the condenser discharge to when the points open?
@@alexiskai there is no energy in the condenser when the points open. They were shorting across the condenser when closed. If you have an oscilloscope you can probe around to see how this works.
Take the condenser out of the circuit and let me know if you get a spark.
Very good explanation but 1 major shortfall. You presented an analog and a digital volt meter in the beginning...and my expectations were that you would use all three ,starting from the simple analog meter and then moving up to your fancy amp clamp. I have an old radio shack analog meter and a cheap walmart DOM, but not an amp clamp.....I was especially expecting use of the analog..., because the condensers were for very old cars..., long before we had digital devices.
Interesting critique. The clamp meter is the only one of the three I own that can do capacitance testing, and its display is much easier for viewers to read, so that's the one I went with. The alternative would be to make an already-long video maybe 50% longer by duplicating the tests. The tests are straightforward in execution and should be able to be replicated by others using basic multimeters (except for the capacitance testing, which requires a separate meter).
@alexiskai some other people test capacitor ,not for the actual value, but just for building charge. Using a very high resistance setting, connect to the capacitor and watch the resistance climb as it charges...and then goes OL, or with the analog the meter pegs. While it does not prove what the actual capacitance is, it does show that there is no dead short, there is no open circuit, and it does take a charge. Some bad capacitors can beep just on the continuity setting, or the opposite can happen where there is an open and the meter shows OL , or the dial does not move at all. If you have a known good capacitor, you can compare the value of resistance achieved , right before it goes OL ..out or range.
@@danieljurgill1681 That's one of the tests I ran in the video.
@alexiskai yes, but you used the high tech meter. You did not mention or show that you could have used the 40 year old or greater analog meter that was introduced in the beginning.
you have points wired incorrect in your drawing points need i side grounded the lift the gd off the capasitor
Both the points and the condenser ground to the distributor body, that's what I was trying to indicate in the diagram.
There is no need for modern points. In a model a.