Capacitor Size

[tonyc]

Great detailed explaination Osteo. Kayak you should be fine if your wiring is correct.

 

[RacerRex]

I've got a question to add to this thread.
Is there a specific capacitor material to use? I see there's aluminum, tantalum etc.
Reason i ask is that i found several capacitors from this website for cheap. http://search.digikey.com/scripts/dksearch/dksus.dll?vendor=0&keywords=25v+capacitor&stock=1
Also they give you many options to choose from like lifetime @ temp, operating temp, ripple current, etc. Whats best to use?
http://search.digikey.com/us/en/cat/capacitors/aluminum/131081?k=25v capacitor&stock=1

 

[tonyc]

I use the Mallory can style with screw tops. E-Bay

 

[osteoderm]

I've got a question to add to this thread.
Is there a specific capacitor material to use? I see there's aluminum, tantalum etc.

Capacitors are one of the basic building blocks of all electronic circuits, and the vast variety of different "flavors" are available to provide for very specific applications in all sorts of circuitry.

The application we are looking at on a bike is a relatively simple one, which doesn't require any of the exotic types at all. Don't sweat the fine print, as it generally doesn't apply to us. Look for 25-50V, at least 30000uF, high(er) temperature, radial-lead cans.

Narrow it down that far and you'll see that there are relatively few(er) choices (mainly aluminium). After that, I'd just pick the one that has a physical size that works best for where you'd like to mount it.

 

[RacerRex]

Awesome. That helps out alot osteoderm.
thanks!

 

[da evil one]

Lowbrow Customs has the purple Sparx back in stock. $15.99. Hugh advised me on that one...its on the way.

 

[xsbrat]

My 2 cents worth...

Capacitors are easy and cheap to source through any number of online electronics dealers. I used Jameco Electronics for mine, but I have no particular preference. I paid $3.50 for each of my four 15000uF caps, but you could probably pay less if you don't need a specific size to fit them into a weird space.

The intimidating part is combing through whatever catalog you find and choosing from the mind-numbing selection. To narrow it down, look for Electrolytic Capacitors, rated for a minimum 25 Volts, DC, with the highest capacitance you can find in a "can"-style that will physically fit your requirements. Don't bother with caps rated above 50VDC unless you can score a killer deal on them. As for capacitance, I'd say 30000uF seems like a minimum, with anything towards 100000uF becoming unnecessary.

Car-audio "stiffening" caps are usually large and expensive, but if you could score a 0.5F "half-size" for cheap somehow, that would work well... 0.5F is 500000uF. Overkill, but they're usually built well enough. The 1.0F "full-size" audio caps are larger than a soda can and heavy; just as well use a battery at that point.

Multiple caps must be wired in parallel (all positive leads together, all negative leads together). If you use multiple caps, they should all be identical. Triple check the polarity! Mis-wired and/or over-charged capacitors can go boom, no joke.

If/when soldering wire leads to caps, be fast and precise with an iron that's hot and controlled enough to get the solder on properly in under a second. Most small capacitors don't like to be point-heated. "Snap-in" and spade-terminal caps will give you a little more soldering latitude than plain wire-lead terminals. Screw-on terminals are best of you can find them.

Caps can hold a charge for a long time, and will discharge all of it at once in a split-second (much faster than a battery). Never short a capacitor (connect the positive and negative), and if you're not sure if or how much a cap is charged, assume that it's full.

Okay, maybe that was 3 cents worth!

Hi just to clarify I'm about to wire in another capacitor a lucas so if I read this right (electrical retard ) if I take another wire off my positive I wire that to the positive of the other capacitor & the same for the negative.
Cheers xsbrat

 

[jefft]

This subject has been debated many times here regarding which capacitor will work with PMA, Pamco. I can't find much in the way of specs on the Accel as compared to the sparkx unit. I still don't know which unit will work. Would 2 of these capacitors wired together be adequate? I tried the Accel and it didn't seem to have enough umph.
jefft

Posted via Mobile

 

[osteoderm]

Hi just to clarify I'm about to wire in another capacitor a lucas so if I read this right (electrical retard ) if I take another wire off my positive I wire that to the positive of the other capacitor & the same for the negative.
Cheers xsbrat

Yes. For capacitors wired in parallel (which is what you want in this application), all the positives go together, and all the negatives go together. Ideally, you want two identical capacitors.

 

[xsbrat]

Yes. For capacitors wired in parallel (which is what you want in this application), all the positives go together, and all the negatives go together. Ideally, you want two identical capacitors.

Thanks for quick response osteoderm both capacitors will be the same Lucas 2MC capacitors easier to get hold of in uk & quicker delivery, running an XSCharge kit, boyer ignition & 1 lucas at present great with lights off not quite enough when lights on don't think the boyer likes the voltage drop when lights switched on ( using a harley style 3 position switch) got another capacitor on order should be here tuesday.

 

[xsbrat]

Problem solved now running 2x capacitors & I fitted an LED stop/tail light I found in the shed no flickering from tail light & can switch lights on without engine struggerling.

 

[RacerRex]

Just ordered this
http://www.ebay.com/itm/130746006486?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[hank hill]

hey racerrex, any word on how that capacitor worked out?

 

[ProSimex]

I just got a 25v 10,000uf rubycon cap from the local electronics shop for under $5. Its the size of my one thumb joint and works great with headlight, tail light, points, and HHB PMA. I got two thinking I would F the first one, but its working fine.

That Ebay cap is massively massive compared to mine, how has it worked out?

 

[RacerRex]

hey racerrex, any word on how that capacitor worked out?

Yeah it worked good for me.
If you have several electronics to run besides a headlight tail and brake light i dont suggest it. My turns dont really work the greatest for some reason, but who need 'em.

 

[ProSimex]

turn signals are overrated.... until its dark out, then it gets kinda scary.

 

[Lasper01]

So would this be OK for PMA and pamco, lights and turnlights?

http://dk.farnell.com/epcos/b41580a5479m000/capacitor-stud-mount-25v-47000uf/dp/1839347

 

[ProSimex]

Only one way to find out! youve got more micro farads there then mine so who knows, could work just tickety-boo with turn signals.