How much capacitance do we consider

[sam67]

I have bought some caps from RS- on line from here in uk..

The caps i got were pan FM and pan FC just been measuring the caps with My micro 4 ESR meter ..now the 2200 uf 10v the Esr is fine yet the capacitance is 2300 over 100 ,is this a big deal or not ? Just wondered because we all seem to focus on ESR but surly the capacitance has to be questioned if it's way off.

[berniedd]

Re: How much capacitance do we consider

No big deal. Electrolytics can be 50% off from their rated capacitance and still be considered okay.

[momaka]

Re: How much capacitance do we consider

Electrolytic capacitors usually have a 20% tolerance. That means when they come out of the factory, their capacitance can be either 20% higher or 20% lower than the stated value. Most circuits that use electrolytic capacitors should be able to cope with this variation just fine.
Not sure about 50% though. Some circuits could tolerate it, others might not.

[Radio Fox]

Re: How much capacitance do we consider

The Panasonic FM & FC range (like many others) have a +/- 20% tolerance, so a reading of 2300uF for a 2200uF capacitor is less than 5%, which is good.

[stj]

Re: How much capacitance do we consider

that 20% is effected by temperature anyway.

put one in the fridge and one on a radiator or against a cup of coffee for a while - then meter them again!

the cold one will meter lower capacitance than the hot one.

[amp]

Re: How much capacitance do we consider

I was pulling some standard brown kzb? 3300uf caps off a am2 biostar motherboard with 2 bad and 3 good ones. The good had 3900 capacitance, the budging ones had more around 1000. Thought 3900 was a bit high, but at like 0.01 esr its hard to trash them.

Swapped them with all 3300uf used rubycon's all reporting 3100 capacitance. Considering the power rail was lacking a good -4500 before capacitance and the computer would still run for a few hours. 3900 makes me think they were over-rated knowing they are bad quality and would degrade after a few years.

[Scenic]

Re: How much capacitance do we consider

+- 20%
20% of 3300uF would be 825uF..
so that cap could be somewhere within 2475uF and 4125uF and would still be in spec..

edit: it's KZG most likely.. a series of Nippon ChemiCon caps that doesn't like heat. at all..

[stj]

Re: How much capacitance do we consider

20% of 3300uF would be 825uF..

you need to recap your calculator,
20% of 3300 = 660!

[shadow]

Re: How much capacitance do we consider

good one there

[Scenic]

Re: How much capacitance do we consider

uhm.. typo when i put it into google calc.. was 3AM when i posted that.. + a couple beers.. lol