Energy transfer between supercapacitor modules using a buck boost DC/DC converter.
By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
This site uses Akismet to reduce spam. Learn how your comment data is processed.
Hi, which fuse do you use in order to protect your capacitors?
If I am not missing something, it should be somewhat easy to add one of those small ebay ammeters that will read the INPUT CURRENT of that buck-boost converter, of course, with minor limitations–but should be worth it to monitor this current.
…I just can't figure out why some of the words are "lined out" in my comments–can other readers see this?
The large bank at 16.3v @ 83F holds a charge of ~1350 coulombs while the small bank of 120F caps holds 16.2V x 20F = 324 coulombs. Assuming ideal charge transfer (yeah, right), the large bank should be able to charge the small bank four (actually 4.16) times. If we are to assume ideal conditions, AND MORE IMPORTANTLY believe that those larger supercaps are really 500F each–I have exactly the same six pack and they are actually much less than 100F each–closer to 80. All the other supercaps I have 10F to 3000F actually agree with the label!! I measured them by employing the formula I=C(dV/dT) and charge with a constant current. …a neat trick: Charge with ONE (1) Amp to one (1) Volt ant the numerical value you get in charge time (seconds) is equal the the capacitance (in Farads) of the supercap. For ex. if ONE amp of current charges the cap to ONE more VOLT in 1min and 23 seconds (83s) then the capacitance of the supercap is 83F. This is about what I get for a SINGLE one of those "500F" labeled caps…wondered why they were so light-weight.
Given that it takes half a second to charge a 10F supercap to 1.5 volt with a standard AA batterie (in fact, I do it with 2 AA batteries, for 3 V, and even if my supercap is limited to 2.7V, it accepts it, for half a second, and my scope confirm that it is then charged at 2.7 volt);
given that it takes 20 minutes to discharge such a single loaded cap through a 22 ohm resistance ( 5 R C = 18.33 minutes );
given that a single ohm add almost a full minute to discharge (or charge), 5 * 10 * 1 = 50 sec. ;
why people insist in adding control "stuff", so adding MANY ohms, for the full life of the charging time?
Sure, avoiding overcharging is important (in theory), but if we are limited to 2.7 volts, say, then we could surely charge it up to, for illustration, 1.5 volt (with the amperage that a single AA battery can deliver) for a "long" 0.5 second, and then make the charging circuit switches in a "control" safe mode, but only for the last tenth of volts of the charge ? That could speed up the charging process which is, imho, quite slow as it is so often depicted in YouTube. And WHY it could be so IMPORTANT to have a constant amperage when charging a super cap?
hey can you safely use this in serial and parallel connection…
lets say 48v at 20 amps….. and then parallel for bigger bank…..
like i want to run a toaster off dc……solar……
like its 2 to 1 to charge your battery….. but its 1 to 1 with capacitors……
will the balance board still work ok
Putting diode across the capacitors to protect against reverse voltage would be a good idea. I understand the military used to do that with their NiCad battery packs. (One reason you don't want to over-discharge a battery pack is because a cell may go reverse voltage. Presumably the diodes allow you to do a deeper discharge.)
I'm hesitant to ask here but I'm really curious and can't seem to find a way to send a pm him, but how does he film from this first person perspective? I'm looking to do the same thing for a few personal electronics videos myself.
Do super capacitors have a life span of storage capability like batteries?
why the buck boost or boost buck? wouldn't a SEPIC better in terms of efficiency?
also as i see this only has 2 components on the heatsink which i presume to be the MOSFET and the Diodes.. so i doupt this is nor boost buck nor buck boost.. i think this is a SEPIC
for those who dont know what a sepic is:
The single-ended primary-inductor converter (SEPIC) is a type of DC/DC converter allowing the electrical potential (voltage) at its output to be greater than, less than, or equal to that at its input. The output of the SEPIC is controlled by the duty cycle of the control transistor.
source: Wikipedia