Potting KEMET Supercapcitors (Perhaps JamesC4S can chime in here?)

Hi all,

I've got an application in which some supercapacitors are used - however, caps like the KEMET FC series, which I am using, (http://www.kemet.com/kemet/web/homepage/kechome.nsf/file/KEM_S6011_FC.pdf/$file/KEM_S6011_FC.pdf), according to the documentation should not be potted. I would however, like to pot the device for a number of reasons.

FM series caps (http://www.kemet.com/kemet/web/homepage/kechome.nsf/file/KEM_S6012_FM.pdf/$file/KEM_S6012_FM.pdf) however, can be?

So, why should the FC series not be potted, whilst the FM can be? I'd like to avoid the FM series, as nobody seems to stock them off the shelf like the FC series.

However, the datasheets says...

"2.5 Cleaning, Coating, and Potting
Except for the FM series, cleaning, coating and potting must not be carried out. Consult KEMET if this type of procedure is
necessary. Terminals should be dried at less than the maximum operating temperature after cleaning."

So, if I still want to pot an FC cap, what is KEMET likely to advise?

Many thanks in advance!

Both types contain sulfuric acid electrolyte. So potting them is like to pot a car battery without any safety vent :slight_smile:
I would consult KEMET..

But, both types? I understand why almost all bulk caps cannot be potted, but why may the FM series be potted?

The manufacturer will know, we can only guess.

MarkT:
The manufacturer will know, we can only guess.

That's the plan - JamesC4S on these forums works at KEMET I believe.

Don't know. I'll find out. I suspect it is something to do with the resin molding of the FM, but not positive.

I'll be in Japan next week, so should have an answer by then.

jtw11:
That's the plan - JamesC4S on these forums works at KEMET I believe.

Yes, I do. However, all of my forum posts are my personal opinions, not officially from KEMET. If you want an "official" response, send a message through the kemet.com web site... (Which, would probably end up coming to me anyway.)

If you would have a few spare moments to ask the question, it would be a great help. Whilst these caps arn't being evaluated for a mass production product, we are looking at using these in quantity batches of ~100s at a time.

Ideally, I'd like to stay away from the FM series - as they don't appear to be regularly stocked at the usual suppliers. The FC caps are ideal for us, being an SMD package - so if there is a set of conditions that will allow us to pot these, great. If not, we can always pot up to a certain level, avoiding the caps.

However, the datasheet also states a guideline 500uA power supply under typical applications, is this the guideline current the supercap is designed to deliver during backup? I need to supply ~5-6mA for 20s or so... The product selector states the FT series being more suitable for ~5mA hold-up currents, which could be made to work with a slight board change. However, these still cannot be readily potted it would appear, although I still wish to be able to...

In terms of derating supercaps, what sort of percentages should be aimed for? There seems to be much less documentation floating about for EDLCs than many other caps. Is a 10-15% voltage derate appropriate at an ambient of ~40degC?

Yes, I do. However, all of my forum posts are my personal opinions, not officially from KEMET. If you want an "official" response, send a message through the kemet.com web site... (Which, would probably end up coming to me anyway.)

In my experience, personal opinions can often be somewhat closer to reality than those that have been passed through 'official' channels, so i'll take your opinion...

Many, many thanks,