How to safely charge and discharge a supercap
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- How to safely charge and discharge a supercap
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In this video we look at one way of safely charging and discharging a supercapacitor. We use a suitable resistor to limit the current and cutoff the power as the cap reaches our desired level of charge. There are other ways to achieve this, but this is a simple method available to anyone with a DC power supply.
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This video made me realize that if you have a power supply with sense terminals, if you put the current limiting resistor on the power line, and have the sense terminals across the capacitor you'll have your power supply do the work for you, switching from constant current to constant voltage once the capacitor is charged. I was thinking about other ways to do this without such a power supplie, and realized that by using a LM317 and a normal power supply you can accomplish the same thing (making sure the power supply is set so that the LM317 doesn't have to dissipate too much power). Just shows how some circuits can be used in unexpected ways, also never thought of using an LM317 to negate lead resistance.
Let's make rail gun!!
Yes!
Back in the day we would charge 1F 12vdc car audio caps with a 12v test light running through a resistor. When the light went out the cap was charged.
Just like the LEDs they put on supercap protection boards.
Yes. There is another good video by a professional doing just that but using a high power incandescent bulb as the resistor. I remember using a 100 watt incandescent bulb to test the power of a morse code transmitter a ham gave me as a kid.
So what can we realistically power from a super capacitor, I've seen some DIY projects using a super cap but none of them would be something practical to use.
I have a hard time finding something useful or practical for the super capacitors, maybe that will change in the future but for now I rather use an 18650 lithium cell just for the power density alone...
When do you expect this to change?
hybrid
How big of a bang would you get if you put the 500f cap accross the mains? LOL.
Deafening
I have a bank of f 6 of those 500F Super Capacitors in series giving 12v. I charged them to only 9v and they ran a simple circuit that flashes 10 LED's with a 12v supply and has a 555 and a decade counter IC. Anyway, that 9v charge ran the circuit for 6 hours. A very cool bank of caps. They were taken from a portable medical defibrillator machine that specs required they be changed every 12-24 months along with the simple circuit board that also divides out a 5v charge as well as the 12v. Very handy for portable work.
I saw a TH-cam video where someone used the larger 500F super cap as the power source for a LiPo battery spot welder.. But they did not say anything about how to protect the Cap while charging/discharging...
for charging circuit:
I would suggest to use an opamp to switch a relay off when the 2.5v limit is reached.
My goal is to spot weld LiPos.. So can you do a video on how to make a proper spot welder for LiPos?
Discharge resistors are your guardian angel in high power Tx, I did 2-3 MHz shipboard radios back in the old days, someone had removed the bleeders on the finals, assuming they would get more power, I went to change the finals and woke up on the floor across the room.
That's scary. I'm glad you are ok.
OK, I was just coming to terms with the idea of one whole Farad, but now.... 500?
Lol yep
look at maxwell K2 3000 farad about 50 bucks. do not short
If you just discharge them by connecting each pin of the cap , will it get burned and destroyed ?
Luckily there was a calculator on the internet. What can we do without the internet? Remember the hand rule; it takes ~5*R*C secs to charge the C to the desired voltage?
Suoercapacitors are fun :)
No explanation of why the resistor is needed or even how to select the right one.
Model trains can be muted these days.....
We can use a step up converter to make a mini flash lights using those super caps!
No KAPPPPPPPPPPPWOOOOOOOOOOOOOOOOOOOOOOOOOOOOWWWWW ?
Everything comes to he who waits....lol
The irony when I'm watching to follow on from what a fella at my work was explaining to me regarding charging a cap on a train that I work on haha
When I finally got an oscilloscope, my first experiment was charging and discharging a capacitor. It was immensely gratifying to see in practice what I had learned in theory.
Mine was running square wave from an arduino. Those things are incredible.
Did you compare the charge and discharge curve to your maths?
Good information for anyone that likes to take the old stuff apart and see how it works. Caps can bite. Thanks for going into the math a bit too.
I immediately raised my hand!
Thanks for the very useful tutorial.Can you please let me know how to charge supercapacitor. I am using 3.5 amp 5.4 volt linear power supply to charge two 35 farad supercapacitor in series. I added 10 ohm 10 watt resistor in series with the positive terminal to prevent the inrush current. The power supply is supplying 1.5 amp now but the 10 watt ceramic resistor is getting very hot. I have not used any diod with it. What should be done? Need your kind suggestions please.
👏👏👏
Nice Video - Charging current = V/R=I as Volts rise exponentially Divided by Time Input current falls as less and less room for charge to be stored. And Discharge Current = V/R=I So 2V7/5R = 0.540Amp at start of Discharge, But falling Volts = Falling Discharge Current. So Discharge taking longer and longer as Volts and Current fall exponentially Divided by Time. A logarithmic process.
Charge and discharge times are both srt by the time constant CR. Five time constants to fully charge and five to fully discharge. This particular example started from partial charge and went to half supply, hence numbers.Discharge should be closer to the math here. Full charge (well near) to zero via five ohms.
Also to anyone who isn't familiar the issue (I don't think it was explained at all) with supercaps is the voltage. They are very fussy about voltage and will not withstand any over voltage. Current wise they don't care. A capacitors raison d'etre is to whack in/out current, it is what they do. Charging time is not any issue at all, it is simply easier to watch and ensure they are not over voltaged by introducing the large time constant. Some caps might not like being discharged with a screwdriver...But most don't care at all.
@@martinda7446 Manufacturers of super capacitors under rate the max user charge voltage with a 10% or 5% margin But Over charging them is not good, that is why you need a Voltage & Charge controlled charger. VV VC detection to switch off when the SC is Charged.
@@uksuperrascal Or keep an eye and a slow ramping charge like here.
Nice video. Could you just set your power supply to 2.5 volts, then you don't have to worry about shutting it off at the end?
You should get more cameras.
Yes, he should!...umm..I take it you have already sent him the money for them?
Now... How to unsafely charge and discharge a super capacitor? Love your videos 😊
Cool Video! it would be interesting to see different charge curve times inserting resistors sequentially. :)
Very interesting. After some testing it appears when power is initially applied to a resistor and capacitor in series, say 9v, their would be a 9v drop across that resistor. As the capacitor begins to charge the potential across that resistor decreases. As the potential decreases so does the current across the resistor. So is that resistor actually to protect the power supply from expelling a massive in rush current and has nothing to do with the cap? It was my understanding an uncharged cap registers as a short circuit to the power supply initially.
This has been a topic I've waited for a while. Great demonstration. The only thing I'll add is that for the resistance part of the equation, a lot of these supercaps (some more than others) have a high level of internal resistance such that in those cases you can connect directly to power rail. Not advised if you don't know what you're doing. The 5v disc ones I sent you fall under that heading.
Damn i hate seeing you get old i know you dont know me but i love you and i hate seeing you get ild ngl skme teres went out my guy love you keep your hed up
What is the brand name of that oscilloscope that you use on this video?
Wow 500 F - Michael Faraday would be proud!
Thanks for shearing this information
Thank you for another great lesson. Cheers Paul 👍
Is it possible to charge them quicker. While maintaining safety and simplicity.
Great video too.
Yes, smaller resistor.
"I hate trains"... Had me LOL 😂
now I need a guitar
'Play with' hehe! 😈
nice ruler
Nice !
Hey, Paul, i got a question, why when it comes to charging a super cap, u can charge it above the rated voltage for this one u used 5V as the power supply?
You can charge it with a voltage above it's rated voltage. But you must not let the cap get over it's rating.
@@learnelectronics it applies on normal cap too?
It’s been a long time since I’ve studied electronics so maybe there’s a simple reason I’m not getting but why not set the power supply to the voltage you want the cap charged to (plus the drop from the resistor)?
I’m no expert but I think the reason is, it will charge a lot faster using a higher voltage.
John That’s what I assumed but if it would be safer I’d rather run it that way
Love these demos.
So I know you need a resistor to get energy into or out of a capacitor. But could you go into why that's the case?
The resistor just limits current. The capacitor will happily dump every joule of energy it holds instantly. Probably destroying the circuit it's in.
Life or death. No sparks or fire. Not evicted if you live in an apartment. Or evicted if you do!
I'm looking to get some 30F 5.5v supercaps for a small project I'm playing with. Should I worry about getting shocked by these given it's only 5.5v that I'm charging with 4.8v?
Fun video Paul. I've been playing with supercaps and they are quite interesting. I think we will see them more and more as they replace batteries.
Yep, I agree.
There are already experiments with supercaps instead of using batteries for storing solar energy.
The big avantage of a supercap is the chargetime that is much lower then a classic lead acid, Li-Po battery etc....
There are people who already replaced the lead acid battery in there car, with a bank of supercaps for starting and powering
the entire car.