Hard Problem with switching Supercapacitors form Series to Parallel ???

Moopy

Joined Aug 15, 2017
17
OK , lets say I have Four , 1F Sup caps, at 2.7 breakdown voltage, each ,

1> I charge them to full in parallel ,
2> then disconnect them from the power supply ,
3> and (still charged ) place them in series,
4> then I connect a load across the series, and discharge them.

What is the output voltage across each cap at discharge ? and do any of the supercapacitors break ?

AlbertHall

Joined Jun 4, 2014
12,328

Moopy

Joined Aug 15, 2017
17
Thanks , that was good to know , but nobody said whether or not the caps brake and why? Which is mainly what I am interested in. I don't know maybe I shouldn't have put hard on the post , But it's certainly hard for me . I'v look into the walton-cockoff multiplier , and Thought it might be something like that , But what is the ground state of a series of full charged capacitors ?

Should I repost this question there ?

AlbertHall

Joined Jun 4, 2014
12,328
When the capacitors are in series and being discharged there is a risk of a capacitor receiving a reverse voltage. The capacitor with lowest capacitance (and even if they are nominally the same value they have a tolerance on the value and they will not all be the same) will discharge to zero volts first. The other capacitors will still have some charge and if the discharge continues then that lowest value capacitor will be reverse charged - bad.

You can avoid this by not discharging too far or by putting reverse schotky diodes across each capacitor rated for the full discharge current.

Bordodynov

Joined May 20, 2015
3,166
See

Moopy

Joined Aug 15, 2017
17
Wow , thank you , what are the colors ? I'm guessing red is charge and green is dis-charge ?

Also what is the voltage between caps ? cap + to other cap -?

Bordodynov

Joined May 20, 2015
3,166
Pins: C1 Cap+=P1 Cap-=M1
C2 Cap+=P2 Cap-=M2
C3 Cap+=P3 Cap-=M3
C4 Cap+=P1 Cap-=GND
Red V(P1), Green V(OUT) Blue V(VCC)
Up to 50 seconds there is a charge (Capacitors Parallel). After 51 seconds, the capacitors are connected in series and all are connected to the load. There is a discharge. And the reverse polarity of the last capacitor (not immediately, but at the end of the discharge) is the smallest capacitance.