If I have two identical capacitors and I connected them in series/parallel what would happen?

Take 10,000uF and 100v, Does that double the voltage or the capacitance? I want to end up with a capacitor bank of around 400v with a capacitance of minimum 8,000uF. So what I'm getting at is what can i change around in terms of capacitors and to what effect. Thanks : D

  • BTW, I'm going for a coilgun here

EDIT:
  • Also, if i'm building a capacitor bank for a coilgun, would i be going for the max capacitance or the max voltage?

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frollard8 years ago
if you put them in series, you'll get double the voltage, but 1/4 the capacitance - because they interfere with each other. If you put them in parallel you'll get twice the capacitance and 1:1 on the voltage. Why does the capacitance go down? because a capacitor as it charges starts to resist the flow of power thru it. When fully charged, there is no flow because the internal voltage directly opposes the input. 2 in series kind of cancel one another out - but since there are 2 you can handle twice the voltage (half each)
pyroten (author)  frollard8 years ago
thx that explained it in a nutshell
http://www.kusashi.com/series-capacitors.php

if for example you use 2 1000uf caps you get 500 total. you would expect 2000.

its the inverse of the sum of the inverses...or something

yeah...

1/( (1/1000) + (1/1000) ) = 500
pyroten (author)  frollard8 years ago
oh okay. but are there any dangers of setting up capacitors in series?
none that you wouldn't see in any capacitor-using circuit - take the same considerations you'd have regarding single capacitors - storing oodles of power and zapping you, etc.
pyroten (author)  frollard8 years ago
Haha okay thanks for that. You explained it well.

Thanks :)
volthead8 years ago
you have to be careful putting caps in series as if the ESR of the caps is higher than the load they will be ruined
dilandou8 years ago
A quick read through this page should help you out.
pyroten (author)  dilandou8 years ago
Thanks, it's pretty informative. So i can double the capacitance, But i still don't get for example, could i get max 400v by stringing the 100v caps together in series? or doesn't it work that way?
Basically if you want a higher voltage you string capacitors together in series. If you want higher capacitance you put them in parallel.
pyroten (author)  dilandou8 years ago
Okay, but are there any disadvantages, say i strung 4 of the mentioned caps together in series, i could get 400v but does the capacitance get dropped?
lemonie pyroten8 years ago
Notice that link says "Two or more capacitors are rarely deliberately connected in series in real circuits" - you'd be best sourcing the right caps' if you can. L
pyroten (author)  lemonie8 years ago
Oh okay. ill try my best
lemonie pyroten8 years ago
Good luck, I came across the phrase "supercapacitor" yesterday - they sound well-good (though probably well-expensive...) L
pyroten (author)  lemonie8 years ago
nah i'm preety sure super capacitors refers to the capacitors with a really high capacitance, eg 5 farads. But the voltage is relativity low :(
sboy3658 years ago
Sorry I can't help, don't know much about capacitors
pyroten (author)  sboy3658 years ago
Okay dw then. But thanks for taking the time :)