Capacitor Size

Im planing and going kick start only and I'm in need of a capacitor. I wanted to buy the Sparx one from Lowbrow but they are sold out and they don't know when they will be back in stock. So if anyone has any suggestion on a different one i would really appreciated it.
Does anyone know what size of capacitor i would need?

osteoderm did an excellent write up about making a 4x15000uf (60000uf) capacitor bank in place of the normal 40000uf capacitor that is sold. You can check it out here starting on post #2.

I’ve seen that one it’s a pretty cool setup curious to see how it holds up to the vibrations and the heat. iv already disassembled the started and made a filler piece out of a 3" cooper tube. I’m just looking for a capacitor to put in it.

I bought two Mallory can-type 32000 micro farad that I will link them giving me 64,000 and 35 volts. This should be enough for my Boyer ignition. The caps were only $5 each from e-bay.

tonyc said:

I bought two Mallory can-type 32000 micro farad that I will link them giving me 64,000 and 35 volts. This should be enough for my Boyer ignition. The caps were only $5 each from e-bay.

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Please note (and ignore me if you already know this), the rules of wiring a capacitor are opposite that of a resistor. Without going into too much detail about why, there are examples below assuming 250 Ohm resistors and 250 microFarad (uF) capicators.

For a resistor: Wired in series the total resistance is the two resistances summed. Wired in parallel the total resistance is the reciprocal of the sum of the reciprocals of the resistances. Confusing much?

In Series -- 250 Ohm + 250 Ohm = 500 Ohm.

In Parallel -- 1/(250 Ohm) +1/(250 Ohm) = .008 -> 1/.008 = 125 Ohm

For a capacitor: Wired in series the total capacitance is the reciprocal of the sum of the reciprocals of the capacitances. Wired in parallel the total capacitance is the two capacitance summed.

In Series -- 1/(250 uF) + 1/(250 uF) = .008 -> 1/.008 = 125 uF

In Parallel -- 250 uF + 250 uF = 500 uF.


So, TonyC, in order to achieve the 64000 uF (64 milliFarads) you must wire your two 32000 uF caps in parallel.

tonyc said:

I bought two Mallory can-type 32000 micro farad that I will link them giving me 64,000 and 35 volts. This should be enough for my Boyer ignition. The caps were only $5 each from e-bay.

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link? I cant find them for less than 25

You may want to check this out.I have the Evo2 on my Xs race bike and it works great so far.Kickstarter only.If you run lights then buy the 4 cells.
http://www.ballisticparts.com/products/batteries/batteries.php

You right Skunk. That is how I am wiring them.

Skunk you made that nice & simple. Thanks for taking the time.

wow, a $100 battery? too rich for my blood.

Im also looking for some thing a bit cheaper then that. plus its to big to fit where i need it to go. so is it looking like i need to get a capacitor(s) that is at least 60000 uf?

Will any of the car audio capacitors work?

Is there any reason you are opposed to a mini battery?

I picked up this battery off of ebay for > $4.00 shipped.

It is small enough to tuck away anywhere, even affixed to the bottom of your seat pan.

I used that tiny 0.8 Ah battery for a couple of years, but I would go with a capacitor, it is just easier in the long run. One benefit is that the capacitor will never go flat like a battery if you leave the key on, plus it is safer to run with a pamco, no chance of frying a pamco with a capacitor unlike a battery.

Try a Lucas capacitor for a Norton.

I finally found the Sparx capacitor that i have been looking for so I’m just going to buy that one and see how it works. Thanks for all the suggestions on the subject.

Hello there, getting ready to switch to a PMA kit. I have been looking at getting a capacitor. The one I am getting ready to buy is a Mallory 68,000 uF 25 VDC with screw on connectors. From what I have been reading, this should work. Is this ok to use?

Kayak that should work fine. Make sure it is wire correctly to avoid any dangers to your system and person.

Just to make sure I don't do anything bad and hurt myself. Is there any special hardware or process involved with the screw in terminals? Or is it pretty straight forward.

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!