Super capacitors

We all start somewhere
User avatar
Mike H
Amstrad Tower of Power
Posts: 17594
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

Re: Super capacitors

Post by Mike H » Thu Apr 26, 2018 6:12 pm

Neal wrote:
Tue Apr 24, 2018 8:44 pm
I would be very careful handling them though and would treat them like a LiPo battery cell. Huge discharge capability and require careful charging IE: current limited or constant current charging and absolutely no over charging.
Kind of what I was alluding to. (Badly. :D )

jack wrote:
Tue Apr 24, 2018 9:19 pm
They were never designed for this type of operation. As noted, just the stored energy is quite dangerous.
Yep well speaking for myself, to borrow a quote from DTB: pole, touch, long, a, wouldn't, with, rearrange words. :lol:
 
I never make the same mistake twice. Instead I prefer to fill my day with a variety of different mistakes

User avatar
pre65
Amstrad Tower of Power
Posts: 17240
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex

Re: Super capacitors

Post by pre65 » Wed May 09, 2018 11:30 am

From what I can gather Stan's supercap PSU is an energy storage module.

So, given that I have a box full of Kemet 22000uf 63v 105C caps (BIG buggers) I could try that (or them :) ) between my DIY 15v power supply and the SEG.

That would test if "energy storage" was the way to go ?
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

User avatar
jack
Shed dweller
Posts: 2850
Joined: Wed Dec 29, 2010 8:58 pm
Location: Somewhere getting hotter with no possibility of rain.
Contact:

Re: Super capacitors

Post by jack » Wed May 09, 2018 12:40 pm

You'd need a lot of them - a 2F capacitor is 100 times bigger (approx) than a 22,000uF one in terms of stored energy.

E = 1/2 * C * V^2

With V being the same (15V), the relative stored energy is directly proportional to C, the capacity in Farads. i.e. you'd actually need 91 of your big Kemets to have the same effect.

:)

User avatar
pre65
Amstrad Tower of Power
Posts: 17240
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex

Re: Super capacitors

Post by pre65 » Wed May 09, 2018 12:49 pm

jack wrote:
Wed May 09, 2018 12:40 pm
You'd need a lot of them - a 2F capacitor is 100 times bigger (approx) than a 22,000uF one in terms of stored energy.

E = 1/2 * C * V^2

With V being the same (15V), the relative stored energy is directly proportional to C, the capacity in Farads. i.e. you'd actually need 91 of your big Kemets to have the same effect.

:)
Yes, I'm sure you are right.

Thing is, how much extra capacitance does one really need ? :?
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

User avatar
Nick
Site Admin
Posts: 11292
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

Re: Super capacitors

Post by Nick » Wed May 09, 2018 1:08 pm

Yes, I'm sure you are right.
I think we can all agree that 2 / 0.022 = 91. So think we can safely say he IS right.
Thing is, how much extra capacitance does one really need ?
I would guess somewhere between plus and minus some, for some value of some.
Resistance isn't futile it's V / I.

User avatar
andrew Ivimey
No idea why I do this anymore
Posts: 6609
Joined: Mon Jun 11, 2007 8:33 am
Location: Bedford

Re: Super capacitors

Post by andrew Ivimey » Wed May 09, 2018 2:15 pm

I would guess somewhere between plus and minus some, for some value of some.
[/quote]

I'm sure you're right Nick.... snigger.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.

User avatar
pre65
Amstrad Tower of Power
Posts: 17240
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex

Re: Super capacitors

Post by pre65 » Wed May 09, 2018 2:23 pm

Ah yes. :lol:

BUT, because my caps are BIG, then my micro farads must be super micro farads as they have more room to work their magic, being extra low ESR helps as well. :wink:
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

User avatar
jack
Shed dweller
Posts: 2850
Joined: Wed Dec 29, 2010 8:58 pm
Location: Somewhere getting hotter with no possibility of rain.
Contact:

Re: Super capacitors

Post by jack » Wed May 09, 2018 2:51 pm

pre65 wrote:
Wed May 09, 2018 2:23 pm
... being extra low ESR helps as well. :wink:
It would be a tiny tiny ESR - with all those 50mOhm caps in parallel, you'd end up with an ESR of about 0R00055.

Now THAT IS A LOW ESR !

But it won't really help you at all...

I used just a few similar but HV (500V) RIFAs to build a disk-platter launcher. As the energy stored is proportional to the square of the voltage, having a higher voltage is far more important than having bigger capacitance (in this use case).

One of my projects on this is at http://4hv.org/e107_plugins/forum/forum ... 98629.post - with just 4 capacitors, I got 2200J with an ESR of 0R015 - enough to vaporise a screwdriver, crush a coke can or fire a 3.5" disk platter so high and fast it punches a hole 30ft up in the ceiling of the warehouse we were in... notice the size of the bussbars I was using and the thickness of the main cables :)

FWIW, 2F @ 15V is only about 10% of the energy in this thing - I originally designed it for 8 capacitors, i.e. 4,400J - easily enough to seriously injure or kill if it suffered from spontaneous energetic disassembly...

Schematic is linked to in the top post - most of the design is to do with safety interlocks to try to prevent folk being seriously hurt - the trigger switch was on a lead about 15ft long and the unit was kept behind a polycarbonate safety screen.

User avatar
pre65
Amstrad Tower of Power
Posts: 17240
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex

Re: Super capacitors

Post by pre65 » Thu Sep 13, 2018 4:41 pm

I've received my Ebay supercapacitor board from China.

Not sure what I'm going to do with it though. :)
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

Post Reply