25v 1f capacitor urgent

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boisrondevens   100 W

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25v 1f capacitor urgent

Post by boisrondevens » Apr 03 2018 6:15pm

I'm looking for 3 or 6 25v 1f capacitor for building a spot welder

anyone?

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spinningmagnets   100 GW

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Re: 25v 1f capacitor urgent

Post by spinningmagnets » Apr 03 2018 6:58pm

I have seen "car starter" capacitor banks made from five Amperics 3V super caps in series to equal 15V max, being used. A separate youtube showed the motor being measured to provide 200A temporary peak to get the motor spinning (for 1/2 second) and then...100A continuous (the fuel pump relay was disconnected and the coil was also). The motor spun for 30 seconds on the 350F capacitor bank...

It may require some experimentation, but...that kind of device might work well. If you series a few low volt capacitors instead of paralleling 25V capacitors, the ESR might be lower (lower resistance = higher sudden peak amps)

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Alan B   100 GW

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Re: 25v 1f capacitor urgent

Post by Alan B » Apr 03 2018 7:26pm

Welding requires one or more thousand amps, takes really low ESR caps. Many caps are not up to it. Lots of fake caps out there. Good ones are not cheap. That's why a lot of welders go with 12V batteries instead.

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boisrondevens   100 W

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Re: 25v 1f capacitor urgent

Post by boisrondevens » Apr 03 2018 10:57pm

I will pay the price :D

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liveforphysics   100 GW

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Re: 25v 1f capacitor urgent

Post by liveforphysics » Apr 04 2018 1:05am

After buying a few fake 1F caps on ebay (a couple useless ultracaps stuffed into a huge can with concrete weight in it), I ended up buying name brand 1F car audio caps from at least 10years ago mfg date, and finally I got caps with welding useful ESR.

That said, a person needs a capacitive welder about as much as you need sand in your eyes. You will be very likely to make damaged cell sketchyness, and if finding caps seems hard it's improbable welding with them will do more than make e-waste.
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amberwolf   100 GW

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Re: 25v 1f capacitor urgent

Post by amberwolf » Apr 04 2018 3:00am

spinningmagnets wrote:
Apr 03 2018 6:58pm
If you series a few low volt capacitors instead of paralleling 25V capacitors, the ESR might be lower (lower resistance = higher sudden peak amps)
Seriesing caps adds their ESR, and decreases the total capacitance....

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spinningmagnets   100 GW

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Re: 25v 1f capacitor urgent

Post by spinningmagnets » Apr 04 2018 11:24am

Series-ing caps adds their ESR, and decreases the total capacitance....
Thanks, sometimes it's hard to get an answer to a newbie question, and I am definitely new to capacitors....

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