Super Capacitors

[Bruce Wrenn]

Been watching several you tubes on super capacitors. Most videos are 8-9 years old. Posters are using them to make jump start boxes, and actually replacing the battery in their car with super capacitors. Maxwell, the leading manufacturer of them has been bought out by Elon Musk. They are used to quickly, as in instantly, recharge using energy from regenerative braking. You can connect a bank of super capacitors to a "dead battery" and it will charge up to enough voltage to crank car. Seems almost too good to be true, except you can now buy commercial super capacitor jump boxes. Some large trucks come with a set installed to help in cranking in cold weather, as they are unaffected by low temps, unlike lead acid batteries. Anybody here have any actual experience with super capacitors?

[Maurice Mcmurry]

I do not but even a small capacitor can give a preson a decent shock. A ceiling fan capacitor for example can make you doubt the off position of a circuit breaker. Cattle prods and electric fence units boast capacitors that feel very super.

[Bill Dufour]

I ran computer case fans on my old woodstove. I ran them at under 10 volts to keep the noise down. They would not always start at such a low voltage. So I installed a one farad capacitor (audio power cap) that was charged up to 17 volts. So when the thermostat heated up it dropped 17 volts onto the fans and the fans spun up to speed for a few minutes until the running voltage dropped down to 10 volts. the caps were fed through a resistor to control the constant running speed.
That cap had enough storage to run the four fans for over two minutes when the power was switched off.
Bill D

[Rich Engelhardt]

Caps scare the crap out of me...

[John K Jordan]

…Anybody here have any actual experience with super capacitors?

I had just one, long ago. It was about about the size of a hockey puck, 5v I think. Did nothing but play with it before passing it to someone else. A near-instant charge would run a small electric motor for a long time.

The energy capacitors can store is sobering. Not so called super capacitors, but we used to spot weld with a bank of big electrolytic caps.

JKJ

[Ken Fitzgerald]

In the mid-70's, I worked air traffic control maintenance at NAS Meridian, MS and NAS Kingsville, TX. While at Meridian, at the national level they designed a new solid state intermediate frequency (IF) section for the precision approach radar receiver to replace the old tube version. We installed it and immediately began having issues with the IF strip intermittantly generating video, saturating the high persistency CRT radar scopes with video whenever the air controllers had to servo the elevation or azimuth antennas to improve the radar target when an aircraft was off centerline or glide slope. This caused the controller to have to wave off the plane until the scope returned to its normal brightness and was again useable. Shortly thereafter, the IF strips started failing with some regularity. The IF strips were made with discrete components including FETs (field effect transtors). In short, it was a major safety issue and a pain for us on the maintenance side.

After some long hours troubleshooting, I determined that the same 28 vdc power supply used to servo the azimuth and elevation antennas was being used to power the new solid state IF strip. When the high current was pulled to servo either of the two antennas, the 28v sagged causing the new logarithmic IF strip to think the IF signal was weak causing it to increase its amplification which in turn, generated its own video which saturated the high persistency CRT radar scopes.

The fix? I installed a diode in series with the incoming 28vdc going to the IF strip and installed a 1200uf electrolytic capacitor to ground between the diode and the IF amplifier. Whenever the antennas were servoed, the 28 vdc dropped reverse biasing the diode and the low current solid state IF strip would run for several minutes off the charge on that capacitor. I developed the fix, was told by my E-8 supervisor to submit it for approval. He felt it saved over $1,000/year in 1973 dollars and improved the safety of the approach radar.

A year later while stationed at NAS Kingsville, TX I got called and ordered to be in dress uniform the next day to meet with the base Captain. The next day, I received a written approval of my fix, a letter of commendation and a check for $28 for my idea. 1200 ufd is a big capacitor in those circuits!

[Maurice Mcmurry]

Why was I poking cows with an electric prod when I should have been in college? Those problems solved are all so clever! Ken you were under paid for your solution. However, the letter of commendation is priceless!

[Bruce Wrenn]

Ken, if you look at videos of guys making welders, using either microwave transformers, or car alternators, most include a capacitor in the circuit to smooth out the arc. Same principle.

[Ken Fitzgerald]

Why was I poking cows with an electric prod when I should have been in college? Those problems solved are all so clever! Ken you were under paid for your solution. However, the letter of commendation is priceless!

Feeding the nation is important too, though it's a fact often overlooked or looked down upon.