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10,000uF capacitor advice
Charlie C - 8/11/18 at 08:15 AM

Hi

I need a 10,000uF capacitor for my COP 12v supply, not being electrically experienced I donít know what Iím looking for or where I should be looking. I would like a capacitor which I donít have to solder in to place and it would be handy if it has spade connectors.
Can anyone recommend a capacitor and where to buy one from online.

Thanks
Charlie


Slimy38 - 8/11/18 at 09:31 AM

Normally I'd say Maplin, but A) they're gone, and B) they would be expensive! Either Farnell or RS would sell them.

I can see RS do ones with screw terminals but the price is significantly higher than the standard solder in ones. Spade terminals are normally reserved for much bigger capacitors, 1F and suchlike. That's mainly due to the physical size I guess?


nick205 - 8/11/18 at 10:07 AM

Excuse any ignorance on my part here, but COP I'm assuming is Coil On Plug?

Speaking to our electronics engineer here at work he suggested RS Components as a source for these. You can buy from RS as a private individual as well.

Our engineer did highlight that such capacitors aren't cheap. The Kemet brand ones he showed me online were £20 each.

He also mentioned it's important to understand the datasheet information for them. Furthermore some of them run hot and are therefore vented so should be mounted with the vent unobstructed to avoid damage to the capacitor.

Alternatively (if it is Coil On Plug) does the original vehicle manufacturer not sell a suitable component?


Charlie C - 8/11/18 at 10:19 AM

Hi
Yes Coil Over Plug
These are going on an MX5 engine which is controlled by a Magasquirt MS3 with MS3X card, the MK1 mx5 didnít have COPís so there is no mazda mx5 standard part.


nick205 - 8/11/18 at 11:36 AM

quote:
Originally posted by Charlie C
Hi
Yes Coil Over Plug
These are going on an MX5 engine which is controlled by a Magasquirt MS3 with MS3X card, the MK1 mx5 didnít have COPís so there is no mazda mx5 standard part.



Understood and thanks for the clarification.


Slimy38 - 8/11/18 at 12:57 PM

quote:
Originally posted by Charlie C
Hi
Yes Coil Over Plug
These are going on an MX5 engine which is controlled by a Magasquirt MS3 with MS3X card, the MK1 mx5 didnít have COPís so there is no mazda mx5 standard part.


You're right there isn't an mx5 part, but I'm 99% sure there is another make that is a common fit for the engine. Have a look on YouTube at some of the big turbo builds or similar, i think you'll find something suitable.


David Jenkins - 8/11/18 at 02:58 PM

Another good supplier is Rapid. Note: I tried to put a link to the exact page for these capacitors, but the site's mechanism broke it. Here's the full line - cut-and-paste it:

https://www.rapidonline.com/Catalogue/Search?Query=capacitor&Tier=Electrolytic%20Capacitors&Attributes={%22Capacitance%22:[%2210mF%22]}

Don't forget that you probably don't want a 12V rating - you will want a good safety margin over that to allow for the way the "12V supply" varies in a car, often up to more than 15V in normal conditions. There are often transient voltage spikes well over that. Maybe a 35V one will do the job, but please take advice. Of course, if this is in a 5V part of the electronics, or the instructions specifically state 12V, then 12V is fine!

Also, I don't know how warm this capacitor will get in an engine compartment; it may be necessary to get one with a higher temperature limit than normal (it's a common requirement, so won't add a lot to the price).



[Edited on 8/11/18 by David Jenkins]


nick205 - 9/11/18 at 10:57 AM

Not being familiar with such things as COP do you need a capacitor per plug or will a single capacitor work across multiple plugs?


Charlie C - 9/11/18 at 11:11 AM

From what I've read its 1 capacitor per 4 cops, i dont know if thats a rule of thumb or what the facts behind that is.


SPYDER - 9/11/18 at 11:24 AM

Hi Charlie! I run two wire ex-Hayabusa COPs in my car with no caps on the supply other than a small suppressor.
It's a good idea to fit "clip-on" ferrite rings to the supply for extra noise rejection.
Is the cap recommended by the COP manufacturer Charlie?


Charlie C - 9/11/18 at 01:45 PM

Hi

The capacitor is recomended by the megasquirt provider and the chap who will be mapping the engine, also there are lots of threads on miata and Mx5 websites which also recomend using a capacitor. My engine is from an mx5 with a turbo added i dont know what differance that makes but the general advice has been the same.


rusty nuts - 9/11/18 at 02:48 PM

Whats the capacity of an old points type condenser, would one of those be any good?


SPYDER - 9/11/18 at 08:45 PM

Points condenser is typically less than half of a microfarad. He needs ten thousand!
I have a low value cap across the supply of my cops to act as a noise suppressor.
The OP needs one to act more as a power reserve/smoothing device I suspect.