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

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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## 17 Replies

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)2009-05-25

thx that explained it in a nutshell

frollard (author)2009-05-25

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)2009-05-25

oh okay. but are there any dangers of setting up capacitors in series?

frollard (author)2009-05-25

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)2009-05-25

Haha okay thanks for that. You explained it well.

Thanks :)

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

dilandou (author)2009-05-24

pyroten (author)2009-05-24

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?

dilandou (author)2009-05-24

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)2009-05-24

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 (author)2009-05-24

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)2009-05-25

Oh okay. ill try my best

lemonie (author)2009-05-25

Good luck, I came across the phrase "supercapacitor" yesterday - they sound well-good (though probably well-expensive...) L

pyroten (author)2009-05-25

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 :(

sboy365 (author)2009-05-24

Sorry I can't help, don't know much about capacitors

pyroten (author)2009-05-24

Okay dw then. But thanks for taking the time :)