# Power supply from super capacitor?

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#### dvdljns

Joined Jul 13, 2021
25
I need a power supply able to run a 2000 what inverter. I have been looking at capacitors to do it. I did find a site where a guy built one that would supply 1200 watts using 6 super capacitor so I would need two of them but was trying to sale the circuit board not the plans. I have been researching and have a few questions. Although I have heard a few explanations I am not sure I really found a good way to be sure input power to the capacitor stays at 2.5 volts under all instances. Also when you put capacitors in series the capacitance halves. Not sure how to get around this. Maybe two are three of the same circuit in parallel . Like 12 volt 10 amps. When I use the inverter I will lose some amperage, right? When I started researching this everyone seemed made it out to sound cut and dried but then I found a post that explained why most limiting circuit did not work on super capacitors. Now I think I am more confused then ever.

#### ronsimpson

Joined Oct 7, 2019
2,403
Super capacitors are not really good for storing energy. (not 2000 watts)
I think you will end up with a battery.

#### dl324

Joined Mar 30, 2015
15,120
So many missing details... What will charge the capacitors? total capacitance? Cap voltage? How long do you need 2kW?

Not likely to work because capacitors, super or otherwise, aren't a good choice.

#### dvdljns

Joined Jul 13, 2021
25
So many missing details... What will charge the capacitors? total capacitance? Cap voltage? How long do you need 2kW?

Not likely to work because capacitors, super or otherwise, aren't a good choice.
I am trying to build this

I have both 12 volt DC and 120 ac in my rv but will probably go with solar for final build for charge to capacitor. That circuit Will give me 120 volts 10 amps and two of them would do the job I want. But I want to learn how to build my own.

#### sagor

Joined Mar 10, 2019
756
He's simply putting 6 capacitors in series. At 2.7V and 500F (if I read that right), he ends up with a 16.2V (maximum voltage) capacitor bank at 500/6 = 83.3F.
A couple of issues:
1) I don't like the way he solders the connections. Not the right way to do it.
2) There are no equalizing resistors across the capacitor bank. There are holes in that PCB to install them.
3) Charging such a capacitor bank with a cheap power supply should have a current limiting resistor. Otherwise, the capacitors look like a dead short to the power supply, which would shut down.

A bank of capacitors like that will not power things for very long. At no time in his video can you tell how long he ruins any of the demonstrations. You can get a good surge of current, but it will not maintain it for very long.
Based on a capacitor vs energy calculator:
http://www.calctool.org/CALC/eng/electronics/capacitor_energy
This setup gives about 2.27Wh (.00227kWh) of stored energy at 14V. That is 0.1362kW minutes, or 8.172kW seconds. In other words, it could provide 2kW of power for about 4 seconds, tops.... (and that ignores voltage drop as it discharges)

Other than some Youtube demonstration, it is useless for any real power supply usage. If you want a reliable inverter power source, use batteries.

#### dvdljns

Joined Jul 13, 2021
25
Super capacitors are not really good for storing energy. (not 2000 watts)
I think you will end up with a battery.
Probably so. But then I have learned two things. Also lead acid battery is not really good at storing energy either but are used for that. Besides I don't really want to store but use it.

#### Papabravo

Joined Feb 24, 2006
19,326
Probably so. But then I have learned two things. Also lead acid battery is not really good at storing energy either but are used for that. Besides I don't really want to store but use it.
I don't think that is a supportable proposition. I use them all the time for mobile radio station operation. The marine deep cycle batteries work well in this application and are optimized to deliver steady power as opposed burst power used for the starter motor in an automobile. They certainly work better than a capacitor bank.

#### MrChips

Joined Oct 2, 2009
27,167
Probably so. But then I have learned two things. Also lead acid battery is not really good at storing energy either but are used for that. Besides I don't really want to store but use it.
What?
There are 1.42 billion cars today with lead acid batteries used for storing the energy required to start the motor.

#### dvdljns

Joined Jul 13, 2021
25
He's simply putting 6 capacitors in series. At 2.7V and 500F (if I read that right), he ends up with a 16.2V (maximum voltage) capacitor bank at 500/6 = 83.3F.
A couple of issues:
1) I don't like the way he solders the connections. Not the right way to do it.
2) There are no equalizing resistors across the capacitor bank. There are holes in that PCB to install them.
3) Charging such a capacitor bank with a cheap power supply should have a current limiting resistor. Otherwise, the capacitors look like a dead short to the power supply, which would shut down.

A bank of capacitors like that will not power things for very long. At no time in his video can you tell how long he ruins any of the demonstrations. You can get a good surge of current, but it will not maintain it for very long.
Based on a capacitor vs energy calculator:
http://www.calctool.org/CALC/eng/electronics/capacitor_energy
This setup gives about 2.27Wh (.00227kWh) of stored energy at 14V. That is 0.1362kW minutes, or 8.172kW seconds. In other words, it could provide 2kW of power for about 4 seconds, tops.... (and that ignores voltage drop as it discharges)

Other than some Youtube demonstration, it is useless for any real power supply usage. If you want a reliable inverter power source, use batteries.
What?
There are 1.42 billion cars today with lead acid batteries used for storing the energy required to start the motor.
I work on a farm and most of the equipment is diesel. I use batteries marked Marine diesel. My biggest expense is those batteries. I always have to replace them. If my boss would let me I would try gel or anything besides lead acid. I don't care how many cars have them. I don't think most people have a choice other alternatives like gel are still new technology relatively speaking and to expensive for a lot of people. As other options get less expensive I think more people will move away from them.
As I understand it a capacitor build up power then when it reaches max power discharges then builds up again in seconds. As long as the input circuit is correct it can do that for years. A battery stores electric energy and in most cases only uses it in short periods as in starting a car. Once the car starts everything is run from the alternator. It is a misinpression that your battery runs the car. Your battery starts the car. If you think a battery is good in your car disconnect the alternator. I remember a job where we had to run lights from batteries and found out that was the worst thing we could have done. Would have been better and cheaper to buy a generator. I don't think I am trying to use this as a battery so much as an alternator. When not in use I don't care if it stores electricity. And keep in mind I am not saying your wrong either. I am saying I don't know and the only way I can be sure is to try it. Believe me I will have a more conventional power source in place in case this don't work.what I am trying to do is really no different then using a diode in a circuit to supply a steady voltage to something in the circuit.

#### dvdljns

Joined Jul 13, 2021
25
He's simply putting 6 capacitors in series. At 2.7V and 500F (if I read that right), he ends up with a 16.2V (maximum voltage) capacitor bank at 500/6 = 83.3F.
A couple of issues:
1) I don't like the way he solders the connections. Not the right way to do it.
2) There are no equalizing resistors across the capacitor bank. There are holes in that PCB to install them.
3) Charging such a capacitor bank with a cheap power supply should have a current limiting resistor. Otherwise, the capacitors look like a dead short to the power supply, which would shut down.

A bank of capacitors like that will not power things for very long. At no time in his video can you tell how long he ruins any of the demonstrations. You can get a good surge of current, but it will not maintain it for very long.
Based on a capacitor vs energy calculator:
http://www.calctool.org/CALC/eng/electronics/capacitor_energy
This setup gives about 2.27Wh (.00227kWh) of stored energy at 14V. That is 0.1362kW minutes, or 8.172kW seconds. In other words, it could provide 2kW of power for about 4 seconds, tops.... (and that ignores voltage drop as it discharges)

Other than some Youtube demonstration, it is useless for any real power supply usage. If you want a reliable inverter power source, use batteries.
I agree there is a big problem with the way he is doing that but that doesn't mean it won't work just that he doesn't need it to for more than a few minutes. There are a lot of people pushing this type of power supply and believe me most of them are not on utube it is true they are not trying to do it on the scale I am. Most of them are using them for small power supply for bench or jump starting there car. But I don't need that.
And there are a lot of issues not handled in any of the article I have looked at like what happens when there is a surge when something comes on.i have not even looked into stuff like that. Also most of the circuits I have looked at claiming these can be used for a battery have a DC to DC amplifier. I have not even looked into that. I assume though I will need one.

#### Ya’akov

Joined Jan 27, 2019
6,609
Unfortunately, the reason you think you “can’t know without trying” is because you don’t understand the fundamental issues you are facing. You also believe “batteries are bad for storing power” because of experiences using them improperly, and confusion and misinformation about the current state of battery technology.

Capacitors are very good for a lot of things, and supercapacitors can be used to supply a lot of current for a very short time, or a little current for a longer time, and have the advantage over batteries in charging not discharging. The numbers provided by the data sheets are enough to know that your proposed application is not suited to them.

Batteries, particularly variations on lead-acid types, are exceptionally good for the sort of thing you are trying to do. Automotive batteries are optimized to provide a lot of current in short times to crank the engine but are not very good at long, slow discharge rates. Deep cycle marine batteries, on the other hand, are very good at providing current over long periods and can be discharged much further than car-starting types.

All engineering is about trade offs, and lead acid batteries aren’t perfect n every way. They are very heavy, for example. But, they are used in the sort of application you propose for a reason—and it’s not ignorance or some hidden agenda.

One more thing. You really need to remember that people here have, by and large, had an engineering career and worked with electronics and power systems for decades. Telling people “car batteries don’t power your engine the alternator does” borders on offensive. I doubt anyone answering your post has less knowledge than you do about automotive electrical systems and the batteries that are part of them.

You are, sorry to say, wasting your time with capacitors. It’s not that people aren’t knowledgeable enough about capacitors to understand they offer some magical alternative to the current technology, it’s quite the opposite. People giving you advice here are much more knowledgeable about the things you find mysterious and can clearly see you won’t be able to make it work.

Good lucK with whatever you do.

[EDIT: Corrected typo that could have lead to a fire. s/short/sort/]

Last edited:

#### Deleted member 115935

Joined Dec 31, 1969
0
capacitors are great

Despite the heading in the video, these are not what electronic engineers call super caps,
Super caps tend to have capacitances of Farads,
where as these have capacitance of u farad.

capacitors are use in things like F1 ( or used to be ) to give an amazing power boost via an electric motor.
The advantage here of using capacitors is they are light, can provide phenomenal high currents,

disadvantage of capacitors ( at the moment ) is the energy stored per cubic cm, and per dollar.

What you want to turn turn the motor or whatever is energy.
measured in Joules.

The energy a given capacitor can store is defined by

E = C * V * V / 2

where C is capacitance in farads,
V is voltage across capacitor

E is the energy stored in joules.

So say you have 1000 uF ( 0.001 F )
and you have 100 volts across it,

Then you have 5 Joules.

That's 100 watts for 5 seconds ,

for comparison, a standard D type Li Ion battery has 24 K Joules of energy.

So yes,
a string of capacitors can provide 100 Amps,
but for a very short time ,

#### LesJones

Joined Jan 8, 2017
3,816
andrewmm, I do not agree with your statement that 5 Joules is 100 watts for 5 seconds.
5 Joules is 1 watt for 5 seconds.

Les.

#### MrChips

Joined Oct 2, 2009
27,167
You are confused between power generation and power storage.

#### Ya’akov

Joined Jan 27, 2019
6,609
You are confused between power generation and power storage.
Parsing one of the later posts, I think you are correct. So the idea capacitors are magical is, in fact, the trouble.

#### BobTPH

Joined Jun 5, 2013
5,798
Besides I don't really want to store but use it.
Then you don’t need a battery or capacitor, do you?

Bob

#### Papabravo

Joined Feb 24, 2006
19,326
...most of the equipment is diesel. I use batteries marked Marine diesel. My biggest expense is those batteries. I always have to replace them.
....
You may be tempted to assume that it is the fault of the batteries. I would question your purchasing choices, along with the care and maintenance of those batteries. When properly treated they have a lifetime that approaches the useful life of the machine they are in.

#### shortbus

Joined Sep 30, 2009
9,646
As I understand it a capacitor build up power then when it reaches max power discharges then builds up again in seconds.
If that is your understanding, answer this question. Where does the "build up" in seconds come from? I don't think you understand at all. But then again, I'm not all that smart.

#### dvdljns

Joined Jul 13, 2021
25
Unfortunately, the reason you think you “can’t know without trying” is because you don’t understand the fundamental issues you are facing. You also believe “batteries are bad for storing power” because of experiences using them improperly, and confusion and misinformation about the current state of battery technology.

Capacitors are very good for a lot of things, and supercapacitors can be used to supply a lot of current for a very short time, or a little current for a longer time, and have the advantage over batteries in charging not discharging. The numbers provided by the data sheets are enough to know that your proposed application is not suited to them.

Batteries, particularly variations on lead-acid types, are exceptionally good for the sort of thing you are trying to do. Automotive batteries are optimized to provide a lot of current in short times to crank the engine but are not very good at long, slow discharge rates. Deep cycle marine batteries, on the other hand, are very good at providing current over long periods and can be discharged much further than car-starting types.

All engineering is about trade offs, and lead acid batteries aren’t perfect n every way. They are very heavy, for example. But, they are used in the sort of application you propose for a reason—and it’s not ignorance or some hidden agenda.

One more thing. You really need to remember that people here have, by and large, had an engineering career and worked with electronics and power systems for decades. Telling people “car batteries don’t power your engine the alternator does” borders on offensive. I doubt anyone answering your post has less knowledge than you do about automotive electrical systems and the batteries that are part of them.

You are, sorry to say, wasting your time with capacitors. It’s not that people aren’t knowledgeable enough about capacitors to understand they offer some magical alternative to the current technology, it’s quite the opposite. People giving you advice here are much more knowledgeable about the things you find mysterious and can clearly see you won’t be able to make it work.

Good lucK with whatever you do.

[EDIT: Corrected typo that could have lead to a fire. s/short/sort/]
Certainly did not mean to offend anyone. also I don't think capacitor or some type of magic bullet for power.. also while I may be trying to use the power in a way that is unusual or maybe even wrong. If I can get it to build up 2000 watts and release it then recharge I have accomplished exactly what I am trying to do. Which is exactly what everyone keeps telling me capacitor or meant to do. True they probably never meant them to build this much power but they can, right? I often think I am not very good at explaining things or making myself understood. Again let me repeat! I want to learn how to build this circuit board and it would be nice to see it work. I live in a rv and have a marine battery hooked up to it with an inverter that runs all the 120 ac items in my rv when needed. I am not expecting to unleach some hidden energy source. If it was that good power plants would be using them. I just did some experiments with solar panels that really surprised me. most of what is being said about them are misleading I bought dozens of solar panels off Amazon and none of them worked as expected. Not really the fault of the panels but more because of the claims being made by the sellers. Most of the 12 volt battery chargers I bought only produced 12 Vols which charged my lawn mower battery to 10 volts. And I live in Texas so have plenty Sun. This is simalar to that. I then bought a 18 volt solar panel and have a fine batery charger. I remember when Instmatic camera came out experts in the filming industry came on the news in Houston and said it would not work out. Developing color film was to complicated to do in one device. But my mom went out and bought one the first week they hit the stores and used one model or another till she died. But it still brings me back to my original question. Can these super capacitors build up 2k watts of power and recharge in seconds and will the experts on this forum help/advise me in building the system?

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