Applying reverse polarity voltage to a capacitor - what will happen?
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- เผยแพร่เมื่อ 26 ส.ค. 2024
- Don't try any of this at home!
What happens if you connect a capacitor in reverse? That is, if you connect it the wrong way and give it voltage of the wrong polarity? I wanted to find out for myself, so here's what happened. This is by no means a scientific test, and the results may differ in other situations.
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We tried 6volt capacitors on 230 volts. Works everytime ! We got cylindric impacts in the ceiling 😂
I'm studying electrical engineering, and I can tell you a few things about electrolytic capacitors:
They can be represented as a standard capacitor with a parallel diode, which is a good representation of how it shorts power when placed with the wrong polarity. Electrolytic capacitors also have the highest ESR out of all capacitors, so low voltages won't necessarily be enough to destroy it as that ESR limits the current going through it, thus reducing the buildup of heat and ultimately pressure. The wikipedia page stating 1.5V is enough to destroy one fails to acknowledge that factors such as size and technology can influence how much fault it can handle. And yes, the grooves on the large capacitors are a countermeasure for overpressure events. Emphasis on 'large' because small ones lack this feature and tend to literally go boom rather than pop and puff, just like the cheap ones you tested.
Thank you for sharing this! I didn't go to school for this, in case it's not obvious :)
@@LeftyMaker No problem. I'd be more than happy to explain electrical (and some mechanical) stuff as long as I've studied it. So yeah, feel free to let me know if you'd like it.
@@SergeantRen2048damn your are cookin 🥞👨🍳
@@LeftyMakerwhere are you studying
You read all that from Wikipedia. You don't learn those things in electrical engineering
In my youth (early teens) I tested hundreds of electrolytic Capacitors on 120 Vac. most went off like a firecracker with stinky smoke. The AC was very effective at destroying them.
Electroboom
Yes
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Yes
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@@Kaloyan-trains What does this mean?
@@MegaTechno he's Bulgarian, most of Bulgaria is underrated
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@@MegaTechno it doesn't, because he's better than most Bulgarians 😉
So that's why Star Trek instrument panels were always exploding.I hate it when that happens.
The other reason you see the bigger pops with the other video was because the smaller caps don't have vents like the bigger ones do, and therefore pressurize more.
That's the thing - all the ones I tested had vents. Probably poorly made ones. But yeah, some very tiny ones don't have them
@@LeftyMaker Yes, and those are the ones that can be fun to explode :D
@@WeedPatch71 more power more explosion. Try it with 230v high current for example
I used to work on industrial electronic systems. I one witnessed a 48VDC drive fail when it was mistakenly wired in reverse. I think the cap was 22000uF rated 63V. It split at the top as you would hope but produced huge amounts of fumes. We had to clear the shop and open a big roller shutter door for about 15 minutes to clear the air.
That thing was probably the size of a soda can :)
I once had a 200-in-1 electro kit (like the Maxitronix 200 in 1 electronics lab kit), which was a plastic case with some cardboard, some resistors, capacitors and transistors mounted on it and you could connect them via the springs that were mounted on it and connected to the components. I built an oscillator circuit using 4 resistors, 2 capacitors and 2 transistors and my LED wasn't blinking. It was supplied with 3 AA batteries, so only 4.5V. After some troubleshooting and looking over the schematic, one of the capacitors blew up with a loud bang, scaring the hell out of me. The casing of the capacitor was on the ground about 4 meters from where I was sitting at my desk and the only thing I had left of that capacitor, were the legs and some twisted paper around the legs, just like in the video at the 4-minute mark. Even my brother came to my room to see what was happening, he heard the bang through a solid brick wall with all doors closed. After troubleshooting, it seemed I connected my batteries with reverse polarity.
1:57 What you see is basically a galvanic cell. You overcame the cell voltage where the surface coating inside the electrolyte is starting to get stripped off. You are basically dissolving the plates of the capacitor into random oxidized junk and whatever gases that electrolyte breaks down to.
A similar example would be an HHO cell. Under 1.23V absolutely nothing happens, then above that you start generating H2 and O2
Interesting. Would the voltage rating of the cap have any effect on the point at which this process starts?
@@LeftyMaker On some capacitors if you limit the current to like 5mA and let the voltage rise the capacitor will form the oxide layer in reverse and if you let it go up to rated voltage the capacitance will be about half of what it should be.
Doesn't work on all capacitors though. most are made differently with the negative electrode doped with other metals that prevent the aluminum oxide from forming correctly. so instead it just electrolyzes the electrolyte until it all breaks down, shorts, or pops.
Only seemed to work on about 1 out of like 20+ random different brands of capacitors I tested.
Now its a crappy 220uF bipolar capacitor instead of a polarized capacitor.
Excellent demonstration ❤❤
Tantalum caps are the most fun. I’ve had them catch fire.
There are three caps on the Amiga 4000's CPU daughterboard that were put in backwards from the factory back in the 90's. Most of them still work fine.
I run these capacitors on reverse bias for specific applications
I know the smell of exploded capacitors very well 😂
There's some good capacitors, and some bad ones. Nice work testing them. "Cheaper" is not usually bad, it's usually the brands.
Nice experiments! I suspect the ones that didn't blow properly were limited too much by the PSU current limit. And the PSU might be slow to resume full output after hitting the limit. We saw the voltage drop way down.
You can make bipolar caps using 2 polarized caps back to back (+ - - +). Works great when needed.
Had a tech classmate whose roomie enjoyed placing a small electrolytic in the bathroom shaver outlet before he would return from evening classes. When he turned the light on the outlet went live & exploded the capacitor. Once it hadn't made contact & he pulled it from the outlet. It connected on being touched & popped in his hand. They discontinued the prank.
it is interesting to do with tantalum capacitor. I often have tantalum reversed in my servise department.
The tantalum cap when reversed don't show damage BUT slowly present a heavy short.
I've accidentally put 120vac across an electrolytic and some diodes in a bias tee, and that definitely does it spectacularly.
Cool investigation!
I would be more scared with that glass jar being on top of it. The cap exploding is violent but the glass jar shattering is even more scary as it can cause real nasty cuts.
Yeah, absolutely I wouldn't have used a glass jar if the caps were bigger. But I don't think these small ones can crack that jar I used
Handy way to make a detonator.
Never stop making videos like this❤
Are yes, this is an example of the safety vent activating by the way, the safety vent is like the pattern on the top 2:45 2:45
*Electroboom likes this*
There is variation from cap to cap, on how much pressure is needed to pop it. To get a bigger bang use much more dc voltage and current say 150V at 100amps+, the idea is to cause the cap to heat up almost instantly, causing a sudden increase in expansive gases, like a bomb. Further you can try to glue up and block the vents, and get enough Power to smash the glass bottle. AC is also works well to blow up caps. Try discharging a huge cap bank 2kV, 10kA? into a small reversed cap, even with A vent, the gasses will expand so quickly the vent will be too slow to release the pressure and the whole thing will explode.
I will try this at home.
wait capacitors have polarity- i'm glad i learned this before i started playing with the big ones i found in a dead stereo lol
Some types do. The electrolytic ones like those in the video are polarized. They can also store charge for a long time after the device is unplugged, so be careful.
Caps in reverse do explode, been there and done that over 20 years ago:)
Great Scott and Electroboom had a baby
question: i use a large cap across the infeed to a very electrically noisy fan…it markedly reduces noise down from 2.4Kz to less than 100hz …there is flyback when power is cut…should i worry about inductive feedback blowing out cap? circuit is 12v @2 amps…cap is rated at 200v…thanks
Is it a polarized type? I guess if it is still working after some time, it is probably fine
Its ok to use polarized electrolytic caps in reverse, provided the voltage is very low, this can occur to block the dc path in cheap audio circuits. The amount of reverse voltage will depend on the cap size and ratings. Non polarized electrolytic capacitors are also available, they are found in cheap audio passive crossovers. Unlike other types of capacitors, the electrolyte dries out over time, where the capacitors need to be replaced, but electrolytic capacitors by far have the highest capacity for there physical size.
It still isn’t good practice to use polarised capacitors in reverse, they aren’t designed for it.
Thank you!
You can actually repair them by reverse biasing them in a controlled way. Look up "reforming electrolytic capacitors".
Also you should just use the alligator clips. The electrolyte is corrosive and will destroy your bread board.
"reverse the polarity of the flux capacitors!" -Someone very wise
Try the same but with tantalum capacitors....
Try the onces without protections and see
The real question is why would it explode there's just two metallic sheets inside filled with electrolyte and a separator so how does it actually explode, my guess is that electrolyte boils pressurising the cap making it go boom but why only the reverse polarity does it ?
The capacitor is only designed to be connected in one direction, if it is connected in reverse parts of it start to break down and produce gas which leads to it exploding.
Electrolytic caps work by having the two conductors being the electrolyte and a self-passivating metal like aluminum or tantalum. The oxide coating on the metal is the dielectric that separates both conductors. Because the oxide layer is extremely thin, you can achieve a high capacitance. However if you apply a negative voltage you chemically reverse the oxidation reaction which strips the coating and thus the electrolyte touches the metal and it goes boom
It'll go BANG!!
😂 no I can't afford the bread boards
Moma told me not to look at eye's of the exploding capacitor, But mama that is where the fun is..
Next time please use tantalum capacitors.
These are known to develop internal short circuits or be sensitive to reverse polarity.
With Tantalum the marking is the positive pole. With Elko the marking is the negative.
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And some really small like 0.22 µF don’t even have it 4:45
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50v cap pop at 12volt?
if u reverse polarity it can
I hope you saved that magic smoke, in case it leaks out of a future project.
❤️
mine blew-up
Likely because the pressure buildup was too fast 4:23
The rated voltage is what’s important. You put -12v across a 50V cap, but if you put -50V it would have been violent.
So the premise is true: do NOT use electrolytic caps backwards or they will explode. They WILL explode.
Why do they have any polarity and what makes them explode inside? That is the real question...
Are you left handed
Yup
@@LeftyMaker same
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00:00 Spoiler: nothing will happen. 😂
It's going to blow Joe make sure it's not pointing at your face
So I was right about the video being about exploding capacitors
It will boom. I did that years ago in school’s electronic lab. I got insulations all over my face. Others: 😮
I know it doesn't always go bang from creating astable multivibrator blinking led circuits.
If you do it right, it feels *and* smells wrong.
Now I know you don't watch ElectroBOOM
If it is a Tantalum Capacitor it might blow up in your face!
I tried this 10/10 caps survive, no explosions, disappointed
Man, I told you not to do this at home :D
@@LeftyMaker I tried it on the second of April
Now all 10 of those caps had the surface polarization stripped due to the backwards current so might as well bin them. I hope you didn't put those bastards back in your misc capacitors box
@@whatevernamegoeshere3644 As long as the test is adequately short it won't damage them. How short is adequately short? I don't know. But the fact polarized capacitors aren't damaged by even low frequency AC means they at least a little reverse polarity tolerance.
@@Kaloyan-trainsI plug caps directly to the wall
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Electroboom